EOs extracted from plant parts.
\r\n\tIn sum, the book presents a reflective analysis of the pedagogical hubs for a changing world, considering the most fundamental areas of the current contingencies in education.
",isbn:"978-1-83968-793-8",printIsbn:"978-1-83968-792-1",pdfIsbn:"978-1-83968-794-5",doi:null,price:0,priceEur:0,priceUsd:0,slug:null,numberOfPages:0,isOpenForSubmission:!1,hash:"b01f9136149277b7e4cbc1e52bce78ec",bookSignature:"Dr. María Jose Hernandez-Serrano",publishedDate:null,coverURL:"https://cdn.intechopen.com/books/images_new/10229.jpg",keywords:"Teacher Digital Competences, Flipped Learning, Online Resources Design, Neuroscientific Literacy (Myths), Emotions and Learning, Multisensory Stimulation, Citizen Skills, Violence Prevention, Moral Development, Universal Design for Learning, Sensitizing on Diversity, Supportive Strategies",numberOfDownloads:null,numberOfWosCitations:0,numberOfCrossrefCitations:null,numberOfDimensionsCitations:null,numberOfTotalCitations:null,isAvailableForWebshopOrdering:!0,dateEndFirstStepPublish:"September 14th 2020",dateEndSecondStepPublish:"October 12th 2020",dateEndThirdStepPublish:"December 11th 2020",dateEndFourthStepPublish:"March 1st 2021",dateEndFifthStepPublish:"April 30th 2021",remainingDaysToSecondStep:"3 months",secondStepPassed:!0,currentStepOfPublishingProcess:4,editedByType:null,kuFlag:!1,biosketch:"Dr. Phil. Maria Jose Hernandez Serrano is a tenured lecturer in the Department of Theory and History of Education at the University of Salamanca, where she currently teaches on Teacher Education. She graduated in Social Education (2000) and Psycho-Pedagogy (2003) at the University of Salamanca. Then, she obtained her European Ph.D. in Education and Training in Virtual Environments by research with the University of Manchester, UK (2009).",coeditorOneBiosketch:null,coeditorTwoBiosketch:null,coeditorThreeBiosketch:null,coeditorFourBiosketch:null,coeditorFiveBiosketch:null,editors:[{id:"187893",title:"Dr.",name:"María Jose",middleName:null,surname:"Hernandez-Serrano",slug:"maria-jose-hernandez-serrano",fullName:"María Jose Hernandez-Serrano",profilePictureURL:"https://mts.intechopen.com/storage/users/187893/images/system/187893.jpg",biography:"DPhil Maria Jose Hernandez Serrano is a tenured Lecturer in the Department of Theory and History of Education at the University of Salamanca (Spain), where she currently teaches on Teacher Education. She graduated in Social Education (2000) and Psycho-Pedagogy (2003) at the University of Salamanca. Then, she obtained her European Ph.D. on Education and Training in Virtual Environments by research with the University of Manchester, UK (2009). She obtained a Visiting Scholar Postdoctoral Grant (of the British Academy, UK) at the Oxford Internet Institute of the University of Oxford (2011) and was granted with a postdoctoral research (in 2021) at London Birbeck University.\n \nShe is author of more than 20 research papers, and more than 35 book chapters (H Index 10). She is interested in the study of the educational process and the analysis of cognitive and affective processes in the context of neuroeducation and neurotechnologies, along with the study of social contingencies affecting the educational institutions and requiring new skills for educators.\n\nHer publications are mainly of the educational process mediated by technologies and digital competences. Currently, her new research interests are: the transdisciplinary application of the brain-based research to the educational context and virtual environments, and the neuropedagogical implications of the technologies on the development of the brain in younger students. Also, she is interested in the promotion of creative and critical uses of digital technologies, the emerging uses of social media and transmedia, and the informal learning through technologies.\n\nShe is a member of several research Networks and Scientific Committees in international journals on Educational Technologies and Educommunication, and collaborates as a reviewer in several prestigious journals (see public profile in Publons).\n\nUntil March 2010 she was in charge of the Adult University of Salamanca, by coordinating teaching activities of more than a thousand adult students. She currently is, since 2014, the Secretary of the Department of Theory and History of Education. Since 2015 she collaborates with the Council Educational Program by training teachers and families in the translation of advances from educational neuroscience.",institutionString:"University of Salamanca",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"0",totalChapterViews:"0",totalEditedBooks:"0",institution:{name:"University of Salamanca",institutionURL:null,country:{name:"Spain"}}}],coeditorOne:null,coeditorTwo:null,coeditorThree:null,coeditorFour:null,coeditorFive:null,topics:[{id:"23",title:"Social Sciences",slug:"social-sciences"}],chapters:null,productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"},personalPublishingAssistant:{id:"301331",firstName:"Mia",lastName:"Vulovic",middleName:null,title:"Mrs.",imageUrl:"https://mts.intechopen.com/storage/users/301331/images/8498_n.jpg",email:"mia.v@intechopen.com",biography:"As an Author Service Manager, my responsibilities include monitoring and facilitating all publishing activities for authors and editors. From chapter submission and review to approval and revision, copyediting and design, until final publication, I work closely with authors and editors to ensure a simple and easy publishing process. I maintain constant and effective communication with authors, editors and reviewers, which allows for a level of personal support that enables contributors to fully commit and concentrate on the chapters they are writing, editing, or reviewing. I assist authors in the preparation of their full chapter submissions and track important deadlines and ensure they are met. I help to coordinate internal processes such as linguistic review, and monitor the technical aspects of the process. As an ASM I am also involved in the acquisition of editors. Whether that be identifying an exceptional author and proposing an editorship collaboration, or contacting researchers who would like the opportunity to work with IntechOpen, I establish and help manage author and editor acquisition and contact."}},relatedBooks:[{type:"book",id:"6942",title:"Global Social Work",subtitle:"Cutting Edge Issues and Critical Reflections",isOpenForSubmission:!1,hash:"222c8a66edfc7a4a6537af7565bcb3de",slug:"global-social-work-cutting-edge-issues-and-critical-reflections",bookSignature:"Bala Raju Nikku",coverURL:"https://cdn.intechopen.com/books/images_new/6942.jpg",editedByType:"Edited by",editors:[{id:"263576",title:"Dr.",name:"Bala",surname:"Nikku",slug:"bala-nikku",fullName:"Bala Nikku"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"1591",title:"Infrared Spectroscopy",subtitle:"Materials Science, Engineering and Technology",isOpenForSubmission:!1,hash:"99b4b7b71a8caeb693ed762b40b017f4",slug:"infrared-spectroscopy-materials-science-engineering-and-technology",bookSignature:"Theophile Theophanides",coverURL:"https://cdn.intechopen.com/books/images_new/1591.jpg",editedByType:"Edited by",editors:[{id:"37194",title:"Dr.",name:"Theophanides",surname:"Theophile",slug:"theophanides-theophile",fullName:"Theophanides Theophile"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3092",title:"Anopheles mosquitoes",subtitle:"New insights into malaria vectors",isOpenForSubmission:!1,hash:"c9e622485316d5e296288bf24d2b0d64",slug:"anopheles-mosquitoes-new-insights-into-malaria-vectors",bookSignature:"Sylvie Manguin",coverURL:"https://cdn.intechopen.com/books/images_new/3092.jpg",editedByType:"Edited by",editors:[{id:"50017",title:"Prof.",name:"Sylvie",surname:"Manguin",slug:"sylvie-manguin",fullName:"Sylvie Manguin"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3161",title:"Frontiers in Guided Wave Optics and Optoelectronics",subtitle:null,isOpenForSubmission:!1,hash:"deb44e9c99f82bbce1083abea743146c",slug:"frontiers-in-guided-wave-optics-and-optoelectronics",bookSignature:"Bishnu Pal",coverURL:"https://cdn.intechopen.com/books/images_new/3161.jpg",editedByType:"Edited by",editors:[{id:"4782",title:"Prof.",name:"Bishnu",surname:"Pal",slug:"bishnu-pal",fullName:"Bishnu Pal"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"72",title:"Ionic Liquids",subtitle:"Theory, Properties, New Approaches",isOpenForSubmission:!1,hash:"d94ffa3cfa10505e3b1d676d46fcd3f5",slug:"ionic-liquids-theory-properties-new-approaches",bookSignature:"Alexander Kokorin",coverURL:"https://cdn.intechopen.com/books/images_new/72.jpg",editedByType:"Edited by",editors:[{id:"19816",title:"Prof.",name:"Alexander",surname:"Kokorin",slug:"alexander-kokorin",fullName:"Alexander Kokorin"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"1373",title:"Ionic Liquids",subtitle:"Applications and Perspectives",isOpenForSubmission:!1,hash:"5e9ae5ae9167cde4b344e499a792c41c",slug:"ionic-liquids-applications-and-perspectives",bookSignature:"Alexander Kokorin",coverURL:"https://cdn.intechopen.com/books/images_new/1373.jpg",editedByType:"Edited by",editors:[{id:"19816",title:"Prof.",name:"Alexander",surname:"Kokorin",slug:"alexander-kokorin",fullName:"Alexander Kokorin"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"57",title:"Physics and Applications of Graphene",subtitle:"Experiments",isOpenForSubmission:!1,hash:"0e6622a71cf4f02f45bfdd5691e1189a",slug:"physics-and-applications-of-graphene-experiments",bookSignature:"Sergey Mikhailov",coverURL:"https://cdn.intechopen.com/books/images_new/57.jpg",editedByType:"Edited by",editors:[{id:"16042",title:"Dr.",name:"Sergey",surname:"Mikhailov",slug:"sergey-mikhailov",fullName:"Sergey Mikhailov"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"371",title:"Abiotic Stress in Plants",subtitle:"Mechanisms and Adaptations",isOpenForSubmission:!1,hash:"588466f487e307619849d72389178a74",slug:"abiotic-stress-in-plants-mechanisms-and-adaptations",bookSignature:"Arun Shanker and B. Venkateswarlu",coverURL:"https://cdn.intechopen.com/books/images_new/371.jpg",editedByType:"Edited by",editors:[{id:"58592",title:"Dr.",name:"Arun",surname:"Shanker",slug:"arun-shanker",fullName:"Arun Shanker"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"878",title:"Phytochemicals",subtitle:"A Global Perspective of Their Role in Nutrition and Health",isOpenForSubmission:!1,hash:"ec77671f63975ef2d16192897deb6835",slug:"phytochemicals-a-global-perspective-of-their-role-in-nutrition-and-health",bookSignature:"Venketeshwer Rao",coverURL:"https://cdn.intechopen.com/books/images_new/878.jpg",editedByType:"Edited by",editors:[{id:"82663",title:"Dr.",name:"Venketeshwer",surname:"Rao",slug:"venketeshwer-rao",fullName:"Venketeshwer Rao"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"4816",title:"Face Recognition",subtitle:null,isOpenForSubmission:!1,hash:"146063b5359146b7718ea86bad47c8eb",slug:"face_recognition",bookSignature:"Kresimir Delac and Mislav Grgic",coverURL:"https://cdn.intechopen.com/books/images_new/4816.jpg",editedByType:"Edited by",editors:[{id:"528",title:"Dr.",name:"Kresimir",surname:"Delac",slug:"kresimir-delac",fullName:"Kresimir Delac"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}}]},chapter:{item:{type:"chapter",id:"67434",title:"Essential Oils: Partnering with Antibiotics",doi:"10.5772/intechopen.86575",slug:"essential-oils-partnering-with-antibiotics",body:'Essential oil (EO) is a concentrated mixture of organic compounds. EOs are produced by plants as a form of defense in addition to being an attractant to insects for dispersion of pollens and seeds [1, 2]. These oils are formed by the glandular trichomes and specialized secretory structure like secretory hairs, ducts, cavities, and glands; they then diffuse to the surface organs of plant such as leaves and flowers [3, 4]. The process of EOs formation involves three pathways which are the methyl-D-erythritol-4-phosphate (MEP), mevalonate, and malonic acid pathways [5]. The MEP and mevalonate pathways contribute in the biosynthesis of isoprenoids, whereas the malonic acid pathway will form the phenolic compounds [6, 7].
EOs have been used for many years for different purposes, such as to preserve raw and processed food because it can inhibit the growth of microorganisms like bacteria, viruses, and fungi [1, 8, 9]. Besides food, EO was also utilized in the area of perfumery for many years especially for ancient civilizations of India, Greece, Egypt, and Rome [10, 11].
In addition, EOs also serve as an alternative medicine that is important for local populations to treat severe burns to accelerate healing [11] and also for diseases such as leishmaniasis, schistosomiasis, and malaria [12, 13]. To date, approximately 10% of all EOs have been analyzed and commercially used as an insect repellent, attributed by its low toxicity to mammalian cells and the environment [10, 14]. However, certain EOs may cause toxicity or allergies which results in health and safety problems. Hence, national and international organizations have set standards to control the use of EOs [15].
EOs can be found in various plants species, in particular those that belong to the Coniferae, Myrtaceae, Rutaceae, Labiatae, Umbelliferae, Alliaceae, and Zingiberaceae families [16, 17]. EOs are derived from different plant parts, such as flowers, leaves, wood, roots, seeds, rhizomes, and fruits [18]. See Table 1 for examples of EOs found in each of the plant parts.
In general, EOs can be classified based on their chemical composition, aroma created by the oil, evaporation speed, taxonomy or the families they belong to, their therapeutic uses, consistency, their origin, and the alphabetical order [16, 30]. Classification based on consistency, for example, can be divided into essences, balms, and resins [16, 31]. See Table 2 for definition and examples of each.
Based on consistency | Definition | Examples |
---|---|---|
Essences | Volatile liquid at room temperature [16] | Lavender, jasmine, geranium, rose [32, 33] |
Balsams | Thick very volatile natural extract from tree or bush [16] | Copaiba balsam, Peruvian balsam, Canada balsam, Tolu balsam, Cabreuva balsam, Bangui balsam [16, 34] |
Resins | Solid or semisolid products that comprise of derivates and abietic acid [16] | Patchouli, sandalwood, frankincense [33] |
Classification of EOs based on consistencies.
Furthermore, there are three classifications of EOs based on their origin which are natural, artificial, and synthetic [16]. The natural EOs are taken from the plant without physical or chemical modifications, while the artificial oils are obtained by enriching the essence with extra components (can be one or more). The synthetic EOs, however, are obtained by combining many chemical substances together [16]. See Table 3 for comparison between natural and synthetic EOs.
Types of essential oil | Disadvantages | Advantages |
---|---|---|
Natural | Expensive, need a lot of natural sources to create, can cause burns if not diluted [15, 35, 36] | Great smell, helpful for physical and mental health [36] |
Synthetic | No therapeutic properties, damaging the skin and respiratory system [36] | Cheap, commonly used as fragrance and taste enhancers, long lasting [15, 36] |
Classification of EOs based on their origin.
Five thousand years ago, the ancient civilizations have already incorporated the use of machines for EO extraction [11]. However, there has been an expansion of the different extraction methods today. One of the important methods is the hydro-distillation which is divided into water distillation, water-steam distillation, and steam distillation [37, 38]. Hydro-distillation method involves hydro-diffusion, hydrolysis, and decomposition by heat [18]. In addition, steam distillation is performed by using the Clevenger system to extract oil from both fresh and dried plants, and it takes about 3 h [1, 11]. Another method is the expression method which utilizes the machines to compress the EO out of the plant [9, 11]. Additionally, solvent extraction and ultrasonic extraction methods are also routinely used [17].
Throughout the distillation process, water is separated by gravity, and at the end it leaves the volatile liquid behind; this liquid is the EO [16, 39]. EOs that are extracted by the use of chemical solvents cannot be called true EOs according to the National Cancer Institute, because they can cause changes in the clarity, scent, and fragrance of the oil [40]. The four criteria that affect the amount of essential oils produced are (1) time of distillation, (2) temperature, (3) pressure, and (4) plant quality.
Hydro-distillation is the most commonly used method of extraction of EOs in which the plant is boiled in water [41, 42]. This method takes 1 h of distillation for fresh samples and 1 h and 15 min for dried samples. In the hydro-distillation method, a round-bottomed flask is used to place the plant material in with distilled water; if the plant material is dry, 1000 ml of distilled water should be used for 75 g of plant material, and if it is fresh material, 400 ml of distilled water should be used with 200 g of plant material; if the sample of plant is smaller, however, they can adjust the amount of water using this ratio: 13.3 ml of distilled water for each gram of dry plant. For water distillation, the modified Clevenger trap should be used to extract EO, and at the end the volume of the oil should be determined, and the EO should be analyzed immediately [43, 44, 45]. An advanced distillation method which is the microwave-assisted hydro-distillation can be used to shorten extraction time [46, 47].
Steam distillation is the traditional method of extraction of EOs from plants [37]. The fundamental principle of steam distillation is that the mixture is allowed to be distilled at a temperature that is lower than the boiling point of the component; EO substances have a high boiling point that can reach 200°C; however, these substances will be volatile when steam or boiling water is present which is in 100°C; then the hot gas mixture will be condensed to form oil if it passes through a cooling system [48]. In steam distillation, the steam is first passed into a flask that contains the plant material; after that the condensate at the bottom of the flask should be collected which will be the water and oil; then the extract is condensated three times with ethyl ether to ensure that the essential oil is fully extracted; then the moisture should be removed by adding sodium sulfate to the ethyl ether, followed by rotary evaporation to remove ethyl ether; and finally the volume of the EO is determined [43]. The advantages of this method of extraction are that it is rapid and can be controlled by the operator and it gives an acceptable quality than EOs extracted with other methods [48].
Solvent extraction method or liquid-liquid method is done by separating compounds based on their part solubility [49]. The basic principle of the solvent extraction method is that between two immiscible solvents, the solute distributes itself in a fixed ratio, whereby one is usually water and the other is an organic solvent [50]. In this method, the plant material will be grinded in a mortar that contains anhydrous hexane Na2SO4, followed by four rounds of extraction with hexane to obtain the yellow extract, then this is followed by adding a sufficient amount of Norite A charcoal for all extracts to remove the yellow color after low-speed centrifugation, and eventually the solution will be concentrated under air stream at room temperature [37, 43, 49]. A newer method of solvent extraction, called the microwave-assisted simultaneous distillation-solvent extraction (MW-SDE), is faster and simpler and uses fewer solvents to determine volatile compounds than conventional methods [51].
EOs are volatile and become liquid at room temperature; they might be colorless or slightly yellow in color when extracted. Moreover EOs are lower in density than water, except for sassafras and clove essences [16]. EOs can be either liposoluble or soluble in alcohol and organic solvents, but they are only slightly soluble in water [4, 16, 32].
Plants metabolites are divided into primary and secondary metabolites. The primary metabolites include proteins, DNA, and compounds that are important for cellular function. Secondary metabolites are produced by plants as a response of stress to deter herbivores or animals that would feed on them [52, 53]. Of the secondary metabolites, plant terpenes are the most numerous and diverse natural products of plant secondary metabolites which can be found in EOs [53]. They are found in monoterpene and diterpene oils and may be aliphatic, cyclic, or aromatic depending on the functional group [16]. According to the functional group, they can be alcohols, esters, ethers, hydrocarbon, and aldehydes [16].
The composition varies due to the place of origin, harvesting moment, extraction method, planting time, mineral fertilization, and climate [5, 16, 54]. For example, in warm places there will be more EOs than the cold or hot areas [16]. The concentration of EOs is extremely high due to the extraction methods used [23]. The simplest unit of EOs is the isoprene units that are composed of five carbons which can be assembled to form terpenes [16, 52]. EOs are composed of hydrocarbon molecules. Terpenes, for example, are hydrocarbon molecules that comprise of 10, 15, 20, and 30 carbon atoms and are made out of five-carbon isoprene units [55, 56].
EOs’ main components are divided into terpenoid and non-terpenoid groups present in different concentrations [4]. The non-terpenoid group contains short-chain aliphatic, aromatic, nitrogenated, and sulfated substances [16, 57]. The terpenoid group contains a different composition of hydrocarbon terpenes, terpenoids, and sesquiterpenes which is responsible for the special aroma [5, 58]. In general, the non-terpenoid group is less important than the terpenoid in terms of applications [53].
Antibiotics are effective drugs that play an important role in treating infections and decreasing morbidity and mortality rates [59, 60]. In general, antibiotics kill multidrug-resistant (MDR) bacteria through various mechanisms. Examples include the β-lactam antibiotics that inhibit the bacterial cell wall synthesis, fluoroquinolones that inhibit DNA synthesis, tetracycline which is an inhibitor of protein synthesis, sulfonamides as a metabolic pathway or folic acid synthesis inhibitor, and polymyxin B which interferes with cell membrane integrity [60, 61, 62, 63]. Antibiotic resistance develops naturally but is accelerated when the antibiotics are misused in both human and animals; the bacteria will evolve and develop resistance toward antibiotics, preventing the antibiotic from killing the bacteria [59, 64]. The bacteria subsequently become resistant by many mechanisms depending on the selective pressure incurred by the antibiotic used; for example, if the penicillin is used, the bacteria will become resistant to it by producing enzymes that will act against the antibiotic which is in this situation penicillinase enzyme [39]. For instance, a study conducted in 173 hospitals in Europe showed that high antibiotic consumption hospitals have a higher number of methicillin-resistant Staphylococcus aureus (MRSA) [65].
Antibiotic resistance in microorganisms is increasing at a worrisome rate [66]. Hence, over the years, researchers are exploring possible alternative sources that will be helpful to mitigate MDR bacteria. Of all the potential sources, EO was identified as one of the good alternative sources, because of their effectiveness in folk medicine [67]. Bacteria can be divided into two main types: the gram-positive and the gram-negative. The gram-positive have a thicker peptidoglycan layer than the gram-negative bacteria [68]. Besides that, the gram-negative bacteria also have an outer membrane that is absent in the gram-positive bacteria (Figure 1).
Schematic of different gram-positive (at the top) and gram-negative (at the bottom) cell walls.
Generally, the gram-positive bacteria are less resistant to EOs than gram-negative bacteria [69, 70]. In gram-positive bacteria, hydrophobic molecules are able to penetrate the cell and act on the cell wall and cytoplasm. This is exemplified by the phenolic compounds in EOs against gram-positive bacteria [66]. In the gram-negative bacteria, a thin layer of peptidoglycans is present with an outer membrane that contains LPS. LPS consists of lipid A, core LPS, and O-side chain, which makes the gram-negative bacteria more resistant to EOs than gram-positive bacteria [66, 71]. Small hydrophilic solutes will make use of the porin proteins in the gram-negative bacteria to pass through the outer membrane; it is this porin selectivity that also makes the gram-negative bacteria less susceptible to hydrophobic antibiotics [66, 72, 73].
EOs via their different components have different targets against microorganisms such as the membrane and the cytoplasm [8]. Scientists have also found that the solubility of EO in water allowed them to decipher how EOs penetrated the cell wall of microbes; in other words EOs, being soluble in the cell membrane phospholipid bilayer, diffuse through the membrane [74]. A study done using the EO of Melaleuca alternifolia (tea tree) against MDR gram-negative bacteria (e.g., Escherichia coli and carbapenem-resistant K. pneumoniae) and methicillin-resistant S. aureus (MRSA) showed that there is a bactericidal effect of tea tree EO on these microorganisms [75]. This indicated that the EO can be used to kill resistant bacteria [74]. Moreover, EO phenolic compounds’ effect is concentration-dependent, whereby at low concentrations the phenolic compound will work with enzymes to produce energy, while at high concentration it will denature proteins [66, 76].
Minimal inhibitory concentration (MIC) is the lowest concentration of a specific drug to inhibit the growth of microorganisms such as bacteria [1, 77]. After knowing that a particular EO has bactericidal, viricidal, and antiparasitic effects, the lowest concentration of EO to inhibit microbial growth should be measured [57, 78]. There are many assays to evaluate and screen for antimicrobial activity such as the disk diffusion test, microdilution (resazurin) or broth method, and agar dilution method [79, 80]. The agar disk diffusion test is commonly used to determine the antibacterial activity of the EO, but this method works only for EO with known components. This is because, for the EOs with unknown components, the antimicrobial effect may give rise to false or negative result caused by the unknown components [81]. Previously, in a study performed using the disk diffusion test to examine the antimicrobial activity of Eucalyptus globulus leaves, EO showed that there was a bacterial inhibitory effect on E. coli and S. aureus [82].
The commonly used alternative method to determine antimicrobial activity is the dilution method through a serial dilution of the EO in several tubes, and then determining the MIC after adding the test microorganism, turbidity is measured as a signal for growth [81]. In this method, the EO is first diluted; then it will be added to the medium that contains the broth culture, followed by incubation for 18 h in 37°C [69]. After the incubation period, the tube with the lowest concentration that showed no sign of growth is the MIC of the EO [69, 83]. However, this method requires a large quantity of the plant extract [81]. A study using the redox dye resazurin for the new modified microdilution method has been carried out to determine the MIC for tea tree EO (Melaleuca alternifolia) against the gram-positive and gram-negative bacteria. The results showed that the resazurin method is accurate to determine the MIC and is higher in sensitivity than the results obtained from the agar dilution assay [80].
EOs’ mechanism of action is poorly understood, but in general it depends on their chemical composition [8, 66, 84]. As antimicrobial resistance to antibiotics is increasing, scientists are currently exploring the ability of the plant extract to modify bacterial resistance against drugs [39]. The three main types of interactions that occur between the combination of antibiotic and EO are synergism, additivity, and antagonism [85]. Synergistic interaction is when the effect of the combined chemicals is greater than the effect of a chemical alone; additive interaction is when the sum of two chemicals is equal to the sum of chemical effect alone, while antagonism is when the whole effect of the two chemicals is less than the sum of effect of a single chemical alone [86]. In a study performed using the tea tree EO against the MDR bacteria, when a combination of tea tree EO with antibiotic (e.g., oxacillin) was tested on the bacteria, in particular the MRSA, a high synergistic index in the sub-inhibitory concentration was recorded [75]. This indicates that the EO can be used to overcome bacterial resistance to antibiotic. The synergism level increases when the combined effect is higher than the individual effect in the combination therapy [39].
Combination therapy is a new method that combines antibiotics and EO to kill resistant bacteria, via enhancement of the antimicrobial activity [39, 87]. Moreover, EOs have more components possessing different mechanisms of actions for many targets than antibiotics that have only one target. Combination therapy would be useful and able to provide a new treatment option for resistance bacteria [39].
Daily, the human body comes into contact with EOs through various sources such as herbs, spices, orange, spearmint, lemongrass, etc., but only limited information about the amount of EO uptake is known [4, 88]. Effects of EO begin to appear after it penetrates the human body in several ways such as by ingestion, by absorbing the EO or diffusion, and by inhalation [4, 89]. EOs can be taken by inhalation through the lungs and distributed into the blood because of their volatility [90, 91, 92]. Moreover, consumption of EO by ingestion should be taken with care because EOs may cause probable toxicity [4]. EOs are used in folk medicine to treat many health problems and can also be used as food preservatives by giving antimicrobial, antioxidant, and anti-inflammation properties [93, 94].
Many studies investigated the efficiency of EOs in combination with antibiotics to combat bacterial resistance; EOs with its compounds and secondary metabolites have shown promising synergistic interaction as an indication that they would be helpful to treat and decrease bacterial resistance to antibiotics [39, 95]. The advantages that make the EOs preferable are that they will decrease adverse reactions, besides being comparatively more cost-effective, with more public acceptance due to traditional usage, and being renewable with better biodegradability properties [39, 96].
The synergistic effects between the EOs and antibiotics against the MDR bacteria have been investigated [97]. The synergistic effect can be defined as the ability of EO components to act together with the antibiotic component to increase the activity of the EO against MDR bacteria [98]. This is important because it will help to reduce the use of antibiotics and decrease the rates of antibiotic resistance [97]. Some studies have been done to assess the combinatory activities of lavender, cinnamon bark, peppermint, and other EOs against bacteria, and the results show there is a synergistic effect [97]. Some of these EOs will be discussed in the following sections.
The lavender EO is used in traditional medicine as well as in cosmetic products; this oil is believed to have sedative, anti-inflammatory, and antimicrobial effects [99]. Lavender EO shows a synergistic effect when combined with piperacillin antibiotic against beta-lactamase-producing Escherichia coli under study with fractional inhibitory concentration (FIC) index between 0.26 and 0.5 [97]. This finding shows that it’s possible to use the lavender EO as an agent in modifying the antibiotic resistance [97]. Another study which aimed to compare the antimicrobial efficacy of four types of lavender oil on MSSA and MSRA shows that by direct contact the oil inhibits the growth of these microbes [100]. Fusidic acid is one of the compounds within this oil which gives it the antimicrobial activity, the mechanism of which is to cause bacterial cell damage by reducing synthesis of proteins [101].
The cinnamon bark EO can be obtained from different parts of the tropical evergreen tree, which is important for human health and agriculture uses [102]. Previously, a study reported that a combination of cinnamon bark EO with piperacillin resulted in a synergistic relationship with FIC ≤ 0.5, and this result indicates the possibility of using cinnamon bark EO as a resistance-modifying agent against MDR bacteria [97, 103]. Cinnamon bark oil contains cinnamaldehyde which is one of the compounds that inhibit the activity of amino acid decarboxylase; this compound with others within the oil gives this oil the ability to inhibit some pathogenic bacteria [104].
Peppermint EO is significant in inhibiting the microbial growth and increasing the shelf-life of food by preventing food spoilage [105]. Combination of piperacillin and peppermint EOs with FIC in the range 0.26–0.5 was found showing a synergistic effect that is absent in 31 other combination pairs that were studied, indicating a promising alternative to reduce the use of antibiotic and achieve the reverse beta-lactam antibiotic resistance [91]. The antibacterial activity for this oil is associated with menthol and ethyl acetate in high concentrations [106].
Research about the reversal antibiotic resistance is important to preserve the healthy microbial ecosystem in the human host. It is imperative to understand the cause of antimicrobial resistance and to find solutions to alleviate the present situation. As discussed above, combination therapy between EOs and antibiotic provides a promising alternative to mitigate MDR bacteria, possibly by disrupting the bacterial cell wall. Although EOs have been proven to be useful for mitigating MDR bacteria spread, there is still much to be done in terms of the combination stability, selectivity, definite mechanism of action, chemical nature, availability of these products in human body, optimal dose, and adverse reactions as a treatment. These gaps need to be taken into consideration before applying EOs for clinical usage. In addition, there is also a need for animal study and human trials in the future, if one intends to employ EOs as a therapeutic option in medical settings.
The authors would like to thank the HCT Research Grants from the Higher Colleges of Technology, UAE for supporting this work.
The authors declare they have no competing interests.
Biomolecules derived from natural resources are playing a major role in manufacturing products needed for daily use. Enzymes are one of those molecules that are globally recognized for their multifarious applications in industries. For instance, their utility in brewing, dairy products, detergents, food and feed, pharmaceutical production, and paper and pulp industry is huge. One of those most widely used enzymes is cellulase. According to recent global cellulase market analysis reports, the demand for this enzyme is exponentially increasing.
\nCellulose, the substrate of cellulase, is the most abundant polysaccharide present on earth. It is the main substance in plant materials. Anselme Payne was the very first person to discover and isolate this amazing compound from green plants [1]. It happened more than two centuries ago. From the past, cellulosic materials have played a crucial role in daily human life. They used it to fertilize their soil for crop cultivation. It was also fodder for their cattle. It was firewood for cooking, and they were igniting cellulosic material to generate heat whenever they needed to produce energy.
\nCurrently, the role played by cellulose is not that simple. Especially, as it is recognized as a cost-effective raw material, the useful applications of cellulose in the industrial sector have become much more complex. This has laid a huge platform for scientists to do cellulose-based research in multidisciplinary approaches. One such area is hydrolysis of cellulose. In nature, this is usually accomplished by cellulases. Cellulase is catalyzing hydrolysis of cellulose.
\nHowever, cellulase is not a single enzyme. It is a group of enzymes which is mainly composed of endoglucanase and exoglucanases including cellobiohydrolases and β-glucosidase. Fungi, bacteria, and actinomycetes are recorded to be efficient cellulase enzyme producers in the natural environment. These microorganisms must secrete cellulases that are either free or cell surface bound. Their enzyme production efficiency and the enzyme complex composition are always diverse from each other. Although both aerobic and anaerobic microorganisms produce these enzymes, aerobic cellulolytic fungi, viz., Trichoderma viride and T. reesei, are excessively studied. The enzyme breaks β-1,4-linkages in cellulose polymer to release sugar subunits such as glucose. This notion is applied in industries either cellulose is utilized as a raw material or cellulose degradation is a must.
\nAccording to recent enzyme market reports, the key areas of the industry where cellulase enzyme is increasingly being applied are healthcare, textile, pulp and paper, detergent, food, and beverages. Its wide application in coffee processing, wine making, and fruit juice production is related to food and beverage segment. In other industrial applications, it is broadly used to produce laundry detergents and cleaning and washing agents. Cellulase is also being highly recognized as an effective alternative to available antibiotics for treatment of biofilms produced by Pseudomonas. Therefore, the potential of cellulases to fight against antibiotic-resistant bacteria is an amazing trend which will overcome problems in the healthcare sector [2].
\nApplication of microorganisms or microbial enzymes for pretreatment of lignocellulosic material is currently earning a huge attention of the industry. This is a result of growing interest about depletion of fossil fuel resources in the world which have inspired the production of bioethanol from lignocellulosic biomass through enzymatic hydrolysis [3]. Lignocellulosic biomass is one of the best options as a low-cost, readily available, eco-friendly raw material. However, it is not found alone. Cellulose is forming lignocellulose in combination with hemicellulose and lignin which finally becomes a compact network structure [4]. Moreover, it has a crystalline structure which is hard to break down. Therefore, cellulose is insoluble in water and causes limitations in hydrolysis. That is why it is essential to pretreat lignocellulosic material in industries like bioethanol production. During pretreatment, it will loosen up the crystalline structure and facilitate the degradability to release fermentable sugar forms. There are several methods available for pretreatment of lignocellulose, viz., physical, chemical, and biological methods. Biological pretreatment using cellulolytic microorganisms and their enzymes is found to be the best way of addressing this problem.
\nBy all means, cellulase is an enzyme which can cause a huge economic impact. However, there are some considerable bottlenecks of utilizing this enzyme in the industry. For example, the higher cost of cellulase and less catalytic efficiency are especially understood. Another important point is less understanding of the relationship between hydrolysis mechanisms and molecular structure of the enzyme. This knowledge is important to carry out further improvements in the enzyme to enhance its catalytic activity. Therefore, this chapter is discussing about the structure and function of cellulase in order to understand its mechanisms of action. The details on current applications of the enzyme have also been summarized here. Furthermore, the efforts have been taken to bring together information on novel biotechnological trends of cellulase. Moreover, it is discussing about possible low-cost, enzymatic pretreatment methods that have been practiced for lignocellulosic materials in order to use it as an efficient raw material to produce bioethanol.
\nBefore moving on to cellulase, it is essential to understand cellulose which is the substrate of cellulase enzyme. This section will provide a short description about cellulose.
\nCellulose is a linear polysaccharide. In this polymer, D-glucose subunits are attached together by formation of β-1,4-glycosidic linkages between individual glucose molecules. The molecular formula of cellulose is (C6H12O6)n. The “n” indicates the degree of polymerization (DP). It symbolizes the number of glucose subunits connected with each other. This number is varying from hundreds to thousands. Two glucose repeating units together are called cellobiose. In other words, this polymer is made by β-(1 → 4)-D-glucopyranose units in 4C1 conformation. It consists of long chains of anhydro-D-glucopyranose units (AGU) with each cellulose molecule having three hydroxyl groups per AGU with the exception of the terminal ends. Cellulose has both crystalline and amorphous regions in its structure in various proportions [5]. Those regions are intertwined to form the structure of cellulose. There are four major crystalline forms, for instance, Iα, Iβ, II, and III. This crystalline structure is a result of intramolecular and intermolecular hydrogen bonding between glucose monomers in cellulose. These hydrogen bonds construct a huge network that directly contributes to the compact crystal structure of cellulose polymer. On the other hand, this strong intramolecular and intermolecular hydrogen bond formation leads to poor solubility of cellulose.
\nIn plant cell walls, cellulose exists as different levels of structures, i.e., single cellulose chains, elementary fibrils (consisting of tens of single cellulose chains), and microfibrils (bundles of elementary fibrils). It is proposed that the macrofibril is composed by the attachment of several newly synthesized elementary fibrils. With the cellular growth, the macrofibrils divide to form individual microfibrils. Microfibril is consisting of a single elementary fibril. Although elementary fibrils and macrofibrils are composed of mere cellulose, microfibril has noncellulosic polymers like hemicelluloses along with cellulose. It is noted that others consider a microfibril as consisting of a number of elementary fibrils. Microfibril is an elementary fibril associated with noncellulosic polymers. Each microfibril might contain up to 40 cellulose chains and is about ~10 to 20 nm in diameter. Many such cellulose chains aggregate into bundles called micelles and micelles into microfibrils. Micelles are interconnected with few cellulose fibers. The plant cell wall structure is stabilized by the macrofibrils. The cross-links between hemicellulose and pectin matrices also support this stabilization process. Lignin is a complex polymer which usually fills the spaces between cellulose and pectin matrices. It forms covalent bonds with hemicellulose. This provides more mechanical strength to the plant cell wall. This structure which is present in plants is collectively called lignocellulose. Other components known as extractives including fats, phenolic, resins, and minerals are also present in lignocellulosic biomass.
\nEnzymes are known to be very useful in many industrial processes. Their broad applicability has created a significant market demand in the recent years. According to market reports on world enzyme demand (2017), they have recognized several key factors which lead to huge consumer demand for enzymes. Some of them are completely bound with economical advances. For example, increased per capita income in developing countries causes huge growth in consumer-related industrial applications [6]. A recent industry study done by Freedonia in January 2018 on “Global Industrial Enzymes” reveals that global demand for industrial enzymes is projected to grow 4.0% per year to $5.0 billion in 2021. This report also emphasizes the gains in personal incomes in developing countries as the key factor which is supporting growth in demand for enzymes. The development of scientific research on enzymes is mainly based on disciplines such as biotechnology,molecular biology and genetics. Continued advances in these areas of research, particularly related to DNA manipulation and sequencing, result in extensive increases in enzyme demand worldwide. Cellulase is one such enzyme which earns consecutively increasing demand. Therefore, collection of knowledge about this enzyme is essential for further development of fundamental and applied research on cellulase and for consequent application in human life.
\nIt is produced by fungi, bacteria, actinomycetes, protozoans, plants, and animals. According to Carbohydrate-Active Enzymes database, there is information of the glycoside hydrolase families. Glycoside hydrolases, including cellulase, have been classified into 115 families based on amino acid sequence similarities and crystal structures. A large number of cellulase genes have now been cloned and characterized. They are found in 13 different families. Furthermore, there are 3D structures of more than 50 cellulases. All of cellulases cleave β-1,4-glucosidic bonds. However, they display a variety of topologies ranging from all β-sheet proteins to β/α-barrels to all α-helical protein.
\nIn the structure of cellulase, there are catalytic modules and non-catalytic modules. The catalytic modules of cellulases have been classified into numerous families based on their amino acid sequences and crystal structures. The non-catalytic carbohydrate-binding modules (CBMs) and/or other functionally known or unknown modules may be located at the N- or C-terminus of a catalytic module. Usually, fungal and bacterial cellulase mainly has two or more structural and functional domains. Both aerobic and anaerobic microorganisms are producing this enzyme. Therefore, there are two types of cellulase systems: noncomplex and complex. A noncomplex cellulase system is produced by aerobic cellulolytic microorganisms, and it is a mixture of extracellular cooperative enzymes. In a noncomplex cellulase system, the common arrangement is joining of a catalytic domain with a cellulose-binding domain (CBD). A complex cellulase system is produced by anaerobic microorganisms and it is called “cellulosome.” Cellulosome is assembled by joining a catalytic domain with a dockerin domain. The enzyme is a multiprotein complex anchored on the surface of the bacterium by non-catalytic proteins that serves to function like the individual noncomplex cellulases but is in one unit.
\nIn addition to these two major domains in the cellulase structure, there are some other domains that are present in many cellulases, for instance, S-layer homologous (SLH) domain, fibronectin-type 111 domains, and NodB-like domain, and there are also other regions of unknown function. These domains are often connected by Pro and hydroxy amino acid (threonine and serine) enriched linker sequences. Among all these domains, catalytic and cellulose-binding domains are the most important because they are the domains which are considered participating in hydrolytic mechanisms of the enzyme.
\nCellulase catalyzes the decomposition of cellulose polysaccharide by simply breaking down β-1,4-glycosidic bonds. Three major types of enzymes are generally involved in hydrolyzing cellulose microfibrils in the plant cell wall: endoglucanase, exoglucanase, and β-glucosidase. Complete cellulose hydrolysis is mediated by the combination of these three main types of enzymes. Endoglucanase usually attacks amorphous areas of cellulose. The random attack of this enzyme on internal bonds of loosely bound, amorphous areas of cellulose creates new chain ends. These new chain ends are then easily attacked by other types of enzymes. The highest activity of this enzyme usually occurs against soluble cellulose forms or acid-treated amorphous cellulose. The function of exoglucanase is to produce glucose or cellobiose units by attacking the reducing or nonreducing end of cellulose chains. Endoglucanase is different from exoglucanase because it is usually very active against crystalline cellulose substrates such as Avicel or cellooligosaccharides. Finally, β-glucosidase can hydrolyze cellobiose to glucose from the nonreducing ends, and it is inactive against amorphous or crystalline cellulose. Although an exact mechanism is not yet finalized, fragmentation of cellulose aggregations into short fibers has been observed and reported during the beginning of cellulose hydrolysis prior to releasing any detectable amount of reducing sugars. This is known as amorphogenesis.
\nThere are two catalytic mechanisms of cellulases. They are simply introduced as retaining mechanisms and inverting mechanisms. Cellulases cleave glucosidic bonds by using acid-based catalysis. The hydrolysis is performed by two catalytic residues of the enzyme: a general acid (proton donor) and a nucleophile/base. The catalytic mechanism which occurs depends on the spatial position of the catalytic residues. The retention and inversion of the anomeric configuration of cellulose are the two mechanisms which hydrolyze cellulose. The “retaining” cellulases retain the same configuration of anomeric C bearing the target glucosidic bond even after a double-displacement hydrolysis with two key glycosylation or deglycosylation steps. “Inverting” cellulases inverts the configuration of the anomeric C configuration after a single nucleophilic displacement hydrolysis [7].
\nFor many decades, cellulases have played a crucial role as biocatalysts. They have shown their potential application in a large number of industries. Textile, paper and pulp, laundry and detergent, agriculture, medicine, and food and feed industries are some of the major industries which employ microbial cellulases. According to Coherent Market Insights, the textile industry is the dominant market for cellulases in 2017. According to most of the enzyme market research reports published in 2018, food and beverages, textile industry, animal feed, and biofuels have been reported to be the major areas of applications.
\nAccording to another Global Cellulase (CAS 9012-54-8) Market Research Report published in 2018, Asia-Pacific is the largest consumer of cellulase, with a revenue market share nearly 32.84% by 2016. Furthermore, the reported data showed 29.71% of the cellulase market demand in animal feed, 26.37% in food and beverages, and 13.77% in the textile industry in 2016. This same report forecasts that the applications of cellulases will reach 2300 million USD by the end of 2025, growing at a compound annual growth rate (CAGR) of 5.5% during the 2018–2025 period. These data suggest that the application of cellulases in industries is drastically rising annually. Novozymes and DuPont from Denmark are key cellulase enzyme producers supplying these enzymes to the global market for industrial applications. From this point forward, in this chapter, our major effort was to discuss about the current applications of cellulases in major fields that have been listed above. The novel biotechnological trends emerging in those fields while understanding the key areas of research where further studies required also surfaced to an extent.
\nThe textile industry is one of the largest industries in the world. The customer demand for fashion is increasing as they want uniqueness in styles, colors, and the clothes they wear. There was a significant growth in this industry during the last few decades as a result of this increasing customer demand. This enzyme has now become the third largest group of enzymes used in these applications [8]. This creates a very competitive market platform for manufacturers that are always looking for environmentally friendly approaches of giving their products a unique look. Cellulase is used for many purposes in the industrial sector.
\nEspecially for textile wet processing, biostoning of denim fabric, biopolishing of textile fibers, softening of garments, and removal of excess dye from the fabrics are some of the major applications of this enzyme in the industry. Fungal cellulases from Trichoderma reesei are the mostly applied enzyme in the textile industry. Apart from that, actinomycetes from the genera Streptomyces and Thermobifida and other genera of bacteria, such as Pseudomonas and Sphingomonas, are some of the sources of enzymes to be used for decolorization and degradation of textile dyes [9].
\nBiostoning and biopolishing are well known for the best applications of cellulases in the current textile industry.
\nThe conventional washing process of denim usually has three steps. The denim fabric is first treated with amylase enzyme to remove the starch coating of the fabric. This process is called desizing. During this process, starch is broken down into maltose which is a water-soluble disaccharide composed of two glucose molecules. Then, the fabric is given treatment by providing abrasion to the material in pumice stones added to the washing machine. This wash was completely achieved by adding chemicals like sodium hypochlorite or potassium permanganate. This traditional process has several disadvantages. The addition of pumice stones must be done in larger quantities. This was affecting the machine’s productivity in an adverse way causing tear effects. After the wash is completed, the manual removal of stones is needed. This is causing further reduction of the process efficiency. The excessive back-staining was another disadvantage of the traditional process. Backstaining is the reaction by which the removed dye molecules are deposited on the denim fabric again.
\nApplication of microbial cellulases was found to be an efficient alternative for pumice stone washing. It was first staged in the 1980s. The use of stones is currently replaced by cellulases in a successful way. During this process, cellulases act on the denim fabric which is made of tough cotton. The indigo dye which is used to color the fabric is trapped inside the cellulose fiber in this cotton material. Usually, the indigo dye is mostly attached to the surface of the yarn and to the most exterior short cotton fibers. When the fabric is treated with the enzyme, it hydrolyzes and breaks small fibers coming out of the fabric which loosens the dye. For this purpose, the β-1,4-linkages of cellulose chains will be broken down, and simple water-soluble sugars will be formed. This will remove the fibers which traps indigo dye. Then, the dye is easily removed from the fabric giving a faded look.
\nTrichoderma reesei acidic endoglucanase II has been found to be a very efficient candidate for biostoning [10]. The neutral cellulase enzyme extracted from Humicola insolens is also reported to be commonly applied in this process [11]. The use of cellulases has several advantages over stone washing with pumice stones including high productivity; less work-intensive, safer environment; short treatment times; and less wear and tear of machines. Currently, denim with a worn-out look has a huge demand in the textile market.
\nThe major disadvantage associated with the application of microbial cellulases is again backstaining. The redisposition of dye on the fabric covers up the shaded look given by the treatment. In order to overcome this problem, several biotechnological approaches have been already experimented by researchers. Immobilization of cellulases on pumice stones is one such cost-effective way of doing this. It has also been observed that acidic endoglucanase causes a better abrasion and less backstaining compared to neutral endoglucanase. For example, the cellulase given by Trichoderma reesei is more efficient in preventing backstaining as compared to neutral endoglucanase of H. insolens.
\nThe latest trend of biostone washing is to utilize an enzyme mixture composed of amylase, cellulase, and laccase [12]. The sizing is the process by which denim material surface is covered by a compound like starch to provide rigidity and stiffness to raw denim and provide strength and friction resistance during handling. During washing, this surface layer of starch must be removed first to facilitate interaction between cellulases and cotton fibers. The amylase hydrolyzes starch from the fabric and causes desizing. Cellulase hydrolyzes small cellulose fibers, and laccase usually causes bleaching of the fabric. Laccases (EC 1.10.3.2) with intrinsic electron-donating tendency can decompose indigo in the solution as well as on the fabric creating bleaching effect on denim garments. The indigo dye is converted into isatin and anthranilic acid like chemical forms. This prevents backstaining of dye on the fabric surface. Eventually, this will give a complete faded look to the denim fabric. The purpose of using a mixture is to improve the efficiency of biostone washing process by allowing those three enzymes to work together in a sequential manner.
\nIn a recent study, it is reported that an alkali-stable cellulase in combination with xylanase from Thermomonospora sp. has a reduced tendency of backstaining [13]. However, the effluents generated during biostone washing must be pretreated to remove dye material and the intermediate chemical compounds present after the reaction. Otherwise, these dyes might pollute natural waterways and soil. Most of these dye residues are toxic and carcinogenic that would cause adverse health effects in humans and animals. Although biodegradability of enzymes is a positive advantage here, chemical by-products formed during dye removal must be neutralized.
\nThese two processes are simply similar to each other. Cellulosic fibrous materials like cotton and linen are always loosing appearance because of fuzz formation on the fabric surface. Fuzz occurred due to short fibers protruding out from the surface of the fabric. Fuzz is sometimes loosely attached to the fabric forming a ball-like appearance which gives an unattractive look to the fabric. This is called pilling. The biopolishing process basically aims on removing microfibrils of cotton. It enhances fabric look, hand feel, and color by giving a smooth and a glossy appearance. This is also leading to improvement of color brightness, hydrophilicity, and moisture absorbance by the fabric [13]. The acidic cellulases produced by T. reesei and Aspergillus niger are found to be enormously effective in this process. Biopolishing is eco-friendly because the enzymes used in this process are readily biodegradable and nontoxic.
\nThe repeated washing of a cotton garment makes it fluffy and dull. This is due to partially removed microfibrils on the fabric surface. Biofinishing by cellulases can remove these fibrils and give back the smooth surface and original color to the fabric. This will also give a soft hand feel to the material, and also this is a good way of removing stains and dirt spots that are trapped within the cotton fiber network [14, 15].
\nThis is the process that removes noncellulosic material from the surface of the cotton. This is usually done with cellulase alone or in combination with other enzymes such as pectinase. Pectinase digests the pectin substance present among cellulose fibers. This helps to remove the intact connection between the cuticle and the main body of the cellulose fiber. This helps to degrade the primary cellulosic wall of the fiber. The ultimate result is the destruction of the cuticle [16]. This reaction increases the softness of the fabric.
\nThis is a kind of a biological mode of cleaning the fabric from the cellulosic or vegetative impurities with the help of enzymes. When a pure cotton or cotton blend fabric is prepared, some traces of unwanted cellulosic material still may remain in the fabric. They may result in imperfect finishing and lower quality of the fabric. The earliest methods of carbonization involved application of sulfuric acid. It was not only expensive but also corrosive, unsafe, and hazardous. Being a nonhazardous, non-corrosive, and eco-friendly method, enzymatic carbonization was a promising alternative. This method was perfect for removal of cellulosic impurities from the material because it was least affecting the color and the hand feel of the fabric. The removal of vegetative impurities from the surface of raw wool using cellulases is called wool scouring [17]. Cellulases can be used alone or in combination with other enzymes such as pectinases to increase the efficiency of this process. These methods are doing less damage to the fabric when compared to the treatment with sulfuric acid.
\nLyocell is the generic name for a biodegradable fabric that is made out of treated wood pulp. This material is used in everything from clothing to cars. This is obtained from wood pulp using a solvent-spinning method. The solvent system which is usually applied is an organic compound called N-methylmorpholine N-oxide. Some main characteristics of lyocell fibers are that they are soft, absorbent, and very strong when wet or dry and resistant to wrinkles. One chief defect of this material is fibrillation. This is the formation of small tangled fibrils on the surface of the fabric. Cellulases can be efficiently applied to remove these fibrils and give the fabric an increased softness and an improved appearance. This is also good for preventing fuzz and pill formation.
\nAlthough the applied enzymes are nontoxic and biodegradable in the above processes, the final effluent produced will show increased biological oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS), and total suspended solids (TSS) to a certain extent because the effluent may contain digested sugar and cellulosic forms. Direct release of this effluent to natural water bodies may cause water pollution. Alkalinity and pH fluctuations of the effluent will also result in polluted water which is not good for human and animal consumption. This may cause health issues like skin irritations in humans. On the other hand, the enzymatic treatments need an incubation period to facilitate the reaction between enzyme and fabric. As this is a fermentation reaction, this may release certain odors to the environment which may cause air pollution to a certain extent. Moreover, textile dyes are removed during textile processing. Most of the dyes are toxic and some are highly carcinogenic. Mixing this type of dyes with water is definitely causing adverse health effects in humans. Therefore, direct release of effluent without applying any pretreatments to neutralize these toxic compounds will breach the stability in ecosystems to which they are released. Therefore, establishment of pretreatment facilities and water quality testing procedures are essential for these enzymatic textile processing plants.
\nLyocell production has a different impact on the environment compared to the other textile polishing and finishing processes. The solvent which is used to manufacture this textile is N-methylmorpholine N-oxide. This is usually causing acute toxicity (oral, dermal, inhalation), skin irritation, serious eye damage and irritation, skin sensitization, and specific target organ toxicity. These are also hazardous to aquatic environments. These possible environmental impacts must be always addressed although application of enzymes in textile processing is eco-friendly.
\nThis is one of the largest industrial sectors in the world. According to the World Wildlife Fund (WWF), the pulp and paper industry, which includes products such as office and catalog paper, glossy paper, tissue, and paper-based packaging, uses over 40% of all industrial wood traded globally [18]. On the other hand, the latest paper industry statistics reveal China, the United States, and Japan as the three countries where the largest paper production occurs in the world. Half of the total paper manufacture of the world is done by these three countries. However, Germany and the United States are the world’s leading paper importers and exporters [19]. Moreover, the United States is reported to be the largest consumer of papers.
\nPapers and pulp are renewable resources. Therefore, recycling and reusing are two popular concepts related to this industry. Application of microbial cellulases is usually utilized for this purpose. The application of cellulases in this industry is broader. Starting from the 1980s up to now the possible applications are branching toward many areas. For instance, deinking, pulping, bioremediation of industry wastes, bleaching, and fiber enhancement can be taken.
\nThe drawbacks in mechanical pulping processes of woody raw materials such as refining and grinding resulted in pulps with higher amounts of fines, bulk, and stiffness. On the other hand, the process was high energy consuming which was not a profitable option for an industry. Meanwhile, biopulping using enzymes such as cellulases is an energy-saving way, and also it is eco-friendly [20]. The substantial energy saving is reported around 20%–40%. During the refining process, it generates small particles of the pulps. These particles reduce the drainage rate during the paper-making process. These particles can be readily degraded by cellulases in order to increase the drainage ability of the pulp. Mixtures of cellulases (endoglucanases I and II) and hemicellulases have also been used for bio-modification of coarse pulp material to improve fiber properties. It is strengthening the hand sheets. On the other hand, biological pulping has the potential to improve the quality of pulp and properties of the paper while reducing energy costs and environmental impact [21].
\nIn traditional deinking, large quantities of chemicals are used which make the method expensive and environmentally damaging and increase the release of contaminants [22]. The main advantage of bio-deinking is the ability of avoiding the alkali use during the process. This prevents yellowing of the paper. Cellulases alone, or used in combination with xylanase, are beneficial for deinking of different types of paper wastes. In most of the applications, partial hydrolysis of carbohydrate molecules releases ink from the fiber surface. This is done by a mixture of cellulases alone or in combination of cellulases and hemicellulases. The advantages associated with enzymatic deinking are clean look of paper, enhanced brightness, as well as environmental pollution reduction..
\nSuccessful application of cellulase and hemicellulase mixtures has been reported to modify properties of fibers. Usually in the paper industry, the making of paper is made easier by improving the beatability, runnability, and drainage of paper pulp during the process. Modifications of fiber properties are also achieved through treatment of paper by cellulase enzyme [20]. Not only that but also the enzymatic hydrolysis helps in characterization of fiber using various techniques such as scanning electron microscopy (SEM) and HPLC [23].
\nThe application of enzymes in manufacturing enzymatic washing agents or biological detergents dates back to the 1960s. Using enzymes in detergent formulae is a common practice today. In fact, according to market reports, by 2014, the detergent industry was the largest single market for enzymes at about 25–30% of total sales [22]. Another market research report published in 2017 on laundry detergent market stated that its global market size valued at 133.3 billion USD in 2016. The latest trend in the industry is to use alkaline enzymes in large amounts. For instance, protease, cellulase, α-amylase, lipase, and mannanase are broadly applied in heavy-duty laundry and automatic dishwashing detergents..
\nThe capability of enzymes to remove stains is the major focus of using them in manufacturing detergents. Cellulases are available in the market in different brands. For instance, Celluzyme® and Carezyme® are two main brands applied in detergent blends. These detergent blends are mainly applied in washing fabrics made of cotton and cotton blends. These detergents are making fiber modifications in the fabric in order to improve color brightness, softness, and particulate soil removal.
\nCellulases extracted from fungi like Trichoderma sp. (T. longibrachiatum, T. reesei, T. viride, and T. harzianum), Aspergillus niger, Humicola (H. insolens and H. griseathermoidea), and Bacillus sp. have been excessively studied so far for application in detergents. Alkaline cellulases are the most suitable additives to conventional detergents. It is because of their ability to remove soil and dirt particles from the interfibrillar spaces of the fabric. The cellulases remove the rough projections of cellulose fibers or cellulose aggregates attached to the fabric. This gives an increased gloss and smoothness to the fabric [23].
\nThe most recent innovation is to use combinations of enzymes in detergents. Cellulases are used in combination with other enzymes like proteases and lipases. The combination of enzymes is used to increase efficiency on stain cleaning and fabric care. For instance, SaniZyme® is a four-enzyme liquid detergent containing lipase, cellulase, amylase, and protease. This is a bacteriostatic enzymatic detergent for the removal of blood, protein, mucous, fats, lipids, and carbohydrates from all types of endoscopic equipment and surgical instruments. Another example is Getinge Clean MIS Detergent® which is also a formulation which includes protease, lipase, amylase, and cellulase enzymes, surfactants, sequestering agents, and corrosion inhibitors (typical pH in use dilution 8) which is specifically designed to clean complex, minimal invasive instrumentation.
\nThe application of cellulases in agriculture is usually reported in enhancement of crop growth and a control agent of plant diseases. For this purpose, combinations of cellulases, hemicellulases, and pectinases are broadly applied. Certain fungal cellulases are with the ability to degrade cell wall of plant pathogens. There are lots of details about application of bacteria such as plant growth-promoting rhizobacteria (PGPR) to improve plant performance. It is reported that these bacteria play a major role in reducing application of chemical fertilizers increasing plant development and also controlling potential plant pathogens and protecting plants from diseases. Moreover, many fungi including Trichoderma sp., Geocladium sp., Chaetomium sp., and Penicillium sp. enhance seed germination, support rapid plant growth, accelerate flowering, improve the root system and increase the crop yield. However, exact mechanisms behind these reactions are not yet clearly understood. But all these organisms have the ability to produce cellulase and related enzymes which may have a direct participation in these reactions. Some reports are about possible synergisms between bacterial cellulase production and bacterial antibiotic production against plant pathogenic fungi.
\nAccording to available information, it is evident that cellulolytic microorganisms are participating in many processes, viz., rhizosphere soil decomposition, increasing the availability of nutrient for the plant, controlling plant pathogens, facilitating root colonization, and penetration of cereal crops improving yields and nutritional contents. However, as there are no solid evidence to prove the mechanisms behind these, this area needs further research. The studies should be performed in order to characterize and improve applications of microbial cellulases in this field.
\nDuring traditional agriculture practices, especially in countries like Sri Lanka, farmers used to add straw and Gliricidia leaves like cellulosic materials into their fields. They observed that the incorporation of these types of plant material not only improved the quality of the soil but also increased the yield due to added nutrients. Therefore, it is obvious that in this type of processes cellulolytic microorganisms must have a direct contribution.
\nMedical pharmacology is currently a very active field of research that novel discoveries are coming into action. One such area is cellulases for development of medicine. By the way, humans are not cellulase producers, but the recent research on health and medicine reveals the benefits of consuming blends of enzymes including cellulase. As a result of global demand for enzyme blends, cellulase produced by the natural fermentation process of Trichoderma reesei and Bacillus licheniformis has been included in commercially available enzyme blends. This type of enzyme blends target collective digestion of cellulose-rich fibrous substances such as fruits and vegetables, cereals, legumes, bran, nuts and seeds, soy, dairy, healthy greens, sprouts, and herbs along with fats (lipids), sugars, proteins, carbohydrates, and gluten. One such example is VeganZyme®. Apart from that digestive aids (e.g., Digestin, P-A-L Plus Enzymes, Polyenzyme Plus, etc.) to treat people suffering from metabolic disorders are evolving as a promising strategy in medicine.
\nIn some records, the direct and indirect applications of cellulase in medicine have been mentioned apart from using it as consumable enzyme blends.
\nCellulase of fungal origin in combination with chitinases and lysozymes has a reported use in chitosan degradation. To obtain chitosan, a partial degradation of chitin must take place. As cellulose, chitin is a structural polysaccharide present in animals such as marine animals like shrimp and insect exoskeleton as well as participates in the formation of some parts of fungal cell walls. Chitin is a poly-ß-1,4-N-acetyl-D-glucosamine, conforming crystalline microfibrils. This polysaccharide provides structural integrity, stability, and protection to animals. Chitosan is the most important semicrystalline derivative form of chitin. This is obtained by partial deacetylation of chitin (around 50%, soluble in aqueous solution) under alkaline conditions or enzyme hydrolysis. Chitosan and its derivatives have many medical applications, viz., surgical sutures, bone rebuilding, production of artificial skin, anticoagulant, antibacterial agent, hemostatic dressings, anticancer and antidiabetic agents (in combination with metals), hypocholesterolemic effectors, elaboration of cosmetics, production of biopharmaceutics, and encapsulation of diverse materials [24, 25].
\nApart from these applications, a lot of reports have been published on several studies which discuss how cellulases hydrolyze chitosan and their potential biomedical effects. For instance, antitumor activity of cellulase-treated chitosan [26] and antimicrobial activity of low-molecular-weight chitosan obtained by Trichoderma commercial enzymes could be discussed. However, the lack of solid evidence is a common issue on this area.
\nA bezoar is a mass found trapped in the gastrointestinal system. Phytobezoars, as its name suggests, are composed of indigestible plant material (e.g., cellulose). In other words, it is a gastric concretion formed by vegetable fibers, seeds and skins of fruits, and sometimes starch granules and fat globules trapped inside the gastrointestinal tract. This is a common problem frequently reported in patients with impaired digestion and decreased gastric motility. Although sometimes surgeries are needed to remove these stagnated substances, certain minor conditions can be treated by cellulases. The common application reported is fungal cellulases. As there are no much reports about application of bacterial cellulases, research can be conducted to find out the application of potential cellulolytic bacterial cellulases to treat this condition. However, what is most important is that any of these individual enzymes or enzyme cocktails should not adversely affect the healthy body cells.
\nAnother possible direct application of cellulase in medicine is degradation of cell walls of pathogenic organisms. Acanthamoeba is a Protista which causes a very rare as well as serious corneal infection which leads to blindness. This is simply called keratitis. This amoebic keratitis is an acute sight-threatening corneal infection associated with contact lens misuse [27]. This organism has two stages in its life cycle: the cyst and trophozoite. Both these structures are available when the eye is infected by this organism. The cyst wall resembles the plant cell wall. It is plausible that amoebae secrete cellulose because its cyst wall is primarily composed of cellulose. There is evidence which has been found to prove this matter about the presence of cellulose in [28]. Therefore, it is possible to apply cellulases in controlling the pathogen which causes this disease. Cellulases can be used to break off the cyst wall and control the pathogen. However, it needs a lot of research before using cellulase as a treatment for the eye.
\nPathogenic microorganisms usually form biofilms. A biofilm is an assemblage of microbial cells that is irreversibly associated (not removed by gentle rinsing) with a surface and is enclosed in an extracellular polymeric substance (EPS) matrix. Usually, pathogenic microorganisms form this type of assemblages. They may be found on a wide range of surfaces including living tissues and indwelling medical devices. Artificial hip prosthesis, central venous catheter, prosthetic heart valve, intrauterine device, and urinary catheter are some examples for indwelling medical devices that are commonly associated with biofilms. Most of the microorganisms produce extracellular polymeric substances composed of backbone structures that contain 1,3- or 1,4-β-linked hexose residues and tend to be more rigid, less deformable, and in certain cases poorly soluble. This is the exact linkages present in cellulose polymer. Therefore, cellulases can be further studied for their efficient application in removing this type of biofilms from medical devices.
\nFood is essential for all living organisms to obtain nutritional support for their growth and well-being. The huge demand for food has laid a path to a very complex, interconnected global business that supplies most of the food consumed by the world’s population.
\nFood biotechnology nowadays considers cellulases as an invaluable resource due to their increased applicability in a broad range of processes. Fruit and vegetable juice clarification, reducing the viscosity of nectars, concentrating purees, alteration of fruit sensory properties, carotenoid extraction, olive oil extraction, and the quality improvement of bakery products are among the various processes in food biotechnology that cellulase is exploited worldwide.
\nThe cloudiness which is usually present in fruit and vegetable juices is a result of floating polysaccharide materials such as cellulose, hemicellulose, lignin, pectin, starch, metals, proteins, and tannins. The presence of these materials in the juice makes it low quality and draws less consumer demand. “Rapidase pomaliq” is a commercially available enzyme preparation composed of cellulase, hemicellulases, and pectinases obtained from Trichoderma reesei and Aspergillus niger. The application of this product in fruit juice clarification was beneficial to a considerable level. It is also reported that cellulase produced by bacteria such as Bacillus and Paenibacillus in combination with other enzymes such as pectinases and hemicellulases carries out the fruit and vegetable juice clarification. Apart from that, treatment of nectars and purees also found to be efficiently carried out by this enzymatic process. Rheological parameters such as viscosity of these products are brought down to a commercially acceptable level.
\nModification of sensory parameters of food is another important area where application of cellulases is highly recommended. The aroma properties, flavor, and texture of fruits are some sensory properties which play a crucial role in food biotechnology. The infusions of pectinases and cellulase enzymes have been found to be effective in altering the sensory properties of fruits and vegetables [29].
\nThese enzymes are also applied in degradation of grape fruit peels to release sugars. These sugars will be used in many industries including food production. Another important application of cellulase is extraction of phenolic compounds from grape pomace.
\nDuring extraction of olive oil, malaxing (mixing) is an indispensable step. This period allows the tiny oil droplets to attach with bigger ones and increase the oil yield which is coming from the olive paste. The use of cellulases alone or in combination with other hydrolytic enzymes like pectinases in this step has been found to have an enhancing effect on the extraction as well as the quality of olive oil. The enzymatic treatment of olive oil at the extraction stage causes significant enhancements in phenolic content and antioxidant activity of olive oil, thereby ultimately improving its quality.
\nThe enzyme cocktails of cellulases with other hydrolytic enzymes such as amylases, proteases, and xylanase result in increased loaf volume, improvement in bread quality, and production of softer crumb. Enzyme cocktail containing cellulases, hemicellulases, amylases, lipases, and phospholipases results in dough conditioning with improvement of flavor, prolonged shelf life, and increase in volume after baking [30].
\nAnother important application of cellulases is in pigment extraction from plants and plant products. Natural pigments such as carotenoids are nowadays earning a huge consumer demand as food colorants because of their natural origin, less toxicity, and availability of a wide range of colors. Brightly colored fruit peels such as orange, sweet potatoes, tomatoes, and carrot cell walls are rich in carotenoids. These are applicable as natural food colorants. The treatment of fruit peels with enzyme cocktails including cellulase leads to carotenoid extraction.
\nIn animal feed production, cellulases are applied to enhance digestibility of cereal-based food and to increase nutritive values for a higher quality of forages. There are reports about efficiently using Trichoderma cellulase as feed additives for significant improvements in feed conversion ratio as well as digestibility of the cereal-based food [31]. Forage feed of ruminants is quite complex in composition containing cellulose, hemicellulose, pectin, and lignin. There is a suggestion that it is possible to use cellulase preparations to enhance digestibility of forage [32, 33]. Usually, cellulase from bacteria such as Bacillus subtilis is used in this feed production and nutritional enhancement processes. Enzyme preparations containing cellulases and hemicellulases are utilized for numerous activities like milk yield, body weight gain, and feed. Another aspect of treating animal feed with these enzyme mixtures is to remove anti-nutritional factors present in grains and other cellulosic materials.
\nFurthermore, cellulases play an important part in increasing the rate and extent of fiber digestion. This can be used as a positive effect on natural gastrointestinal processes of the ruminants. The ultimate result will be the increased availability of absorbable nutrients by digestibility enhancement of fodder. The partial hydrolysis of lignocellulose materials also leads to better emulsification of food in the animal digestive tract resulting in ultimate improvement of nutrients availability.
\nEnergy is the life blood of the modern world. Fossil fuel, among all energy sources, holds the highest consumer demand. Since the industrial revolution, there is a drastic increase in fuel consumption. As fossil fuels are not renewable resources, the depletion of its natural deposits is inevitable. Therefore, we are in an era of limited and expensive energy. With the recent rise in fossil fuel prices, along with growing concern about its adverse effects on environment such as global warming caused by carbon dioxide emissions and subsequent climate change problems, biofuels have been gaining popularity. In our study area, we are focusing on bioethanol production using cellulolytic microorganisms as well as fermentative yeast using cellulose as the substrate.
\nBioethanol is a renewable form of energy. Especially, second-generation bioethanol production is an emerging trend because of the abundance of low-cost raw materials. The largest potential feedstock for this purpose is lignocellulosic biomass, which includes materials such as agricultural residues (corn stover, crop straws, and bagasse), herbaceous crops (alfalfa, switch grass), short-rotation woody crops, forestry residues, waste paper, and other wastes (municipal and industrial). Lignocellulose is the most abundant renewable biomass. The yield of lignocellulose can reach approximately 200 billon metric tons worldwide per year [34]. Bioethanol production from these feedstocks has certain advantages. It is an attractive method of disposing those lignocellulosic materials which is the nonedible part of plants. Less production of pollutants makes it environmentally friendly. Most importantly, bioethanol production using lignocellulosic biomass does not create any food insecurity because it does not utilize any food crops before harvesting. Finally, it is abundant all around the year as a raw material.
\nHowever, the major drawback of this production process is associated with the structure of lignocellulosic biomass. It mainly consists of lignin, cellulose, and hemicellulose which collectively form a very stable structure. In order to release fermentable sugars from this substrate, it needs to undergo a pretreatment process to break open the stable structure. One of the main focuses of this chapter is to discuss about the possible biological pretreatment of lignocellulosic biomass with special references to the current studies conducted by scientists. It also includes a description about our own attempts in this particular area of research.
\nBiomass contains about 40–50% of cellulose, a glucose polymer; 25–35% of hemicellulose, a sugar heteropolymer; 15–20% of lignin, a non-fermentable phenyl-propane unit; and lesser amounts of minerals, oils, soluble sugars, and other components. Biological pretreatment of lignocellulosic biomass uses the ligninolytic potential of certain microorganisms (fungi and bacteria and actinomycetes) to reduce the recalcitrant nature which is mainly caused by lignin component of the feedstock and enhance its digestibility by hydrolytic enzymes [35]. The breakdown of lignin barrier changes the structure of lignocellulose and enhances the access to the cellulose and hemicellulose carbohydrate components present.
\nBiological pretreatment seems to be a promising approach due to its low capital cost, low energy, and little dependence of chemicals, mild environmental conditions, eco-friendly nature, and the absence of inhibitor generation during the process which affects in bioethanol production. Moreover, this process does not release any toxic materials or any toxic effluents to the environment.
\nHowever, there are few limitations in this strategy. The main drawback against the industrial scale application is the prolonged incubation time consumed to achieve the efficient delignification [36]. This is because of low hydrolysis rate of the microorganisms. Another possible drawback that comes into mind is the possible consumption of carbohydrates as well as fermentable sugar formed by the same microorganisms used to pretreat the material. This is possible to take place because most of the lignolytic microorganisms are producing cellulolytic enzyme batteries as well. Then, the substrate left for fermentative organisms will be minimal which could consequently lead to lower bioethanol yields. Therefore, it is essential to have poor cellulolytic microorganisms for delignification process.
\nTo minimize this type of drawbacks in a biological way, it is possible to use cocultures or biofilms of efficient ligninolytic microorganisms. Introduction of fermentative yeast isolates into the same microbial coculture would also be a perfect approach. However, developing the most efficient microbial consortium is not that simple. Excessive laboratory-scale studies are required to understand the optimum physiological as well as biochemical parameter setup.
\nFungi are found to be more efficient in degrading lignocellulosic biomass. For instance, white-rot fungi, brown-rot fungi, and soft-rot fungi can be taken. The first two are basidiomycetes and soft-rot fungi are classified in ascomycete group.
\nAmong these efficient ligninolytic microorganisms that have been studied so far, white-rot basidiomycete fungi are found to be more versatile in the process. Most research has been concentrated on species such as Phanerochaete chrysosporium (Sporotrichum pulverulentum) which is considered as the model organisms for lignin degradation as it completely mineralizes lignin to CO2 and water. Ceriporiopsis subvermispora, Phlebia subseralis
Recently, some bacterial laccases have also been characterized from Azospirillum lipoferum, Bacillus subtilis, etc. Unlike fungi, the bacteria are considered as low potential for lignin degradation. However, the three groups of bacteria, namely, actinomycetes, α-proteobacteria, and γ-proteobacteria, are known to have ligninolytic systems. Some actinomycetes were studied for their role in lignin biodegradation [37]. These degraded lignin into low-molecular-weight fragments. Some studies have shown potential of Penicillium camemberti for lignin degradation.
\nThe biological pretreatment can be performed by growing the microorganism directly on the feedstock or using the enzyme extracts. Solid-state fermentation is the method of choice for biological delignification. Thus, from the reports available, it is evident that white-rot fungi and actinomycetes can be used to remove lignin from lignocellulosic substrates. However, further studies are required to shorten the incubation time and to optimize the delignification process.
\nThe importance of enhancing enzymatic hydrolysis has been increased because of the urgent need for efficient biological pretreatment processes. For this purpose it is essential to search for high enzyme-producing organisms from the natural environment. Selecting the most effective strain and its culture conditions can make the process more efficient. Another important aspect is to find unique microbial communities for biological pretreatment. These communities can be called consortia. The efficient biodegradation of lignocellulosic biomass could be achieved by the synergistic action of various bacteria and fungi in a microbial consortium. There are a number of advantages in using a microbial consortium for biological pretreatment. The increase of adaptability, improved productivity, improved efficiency of enzymatic saccharification, control of pH during sugar utilization, and increase in substrate utilization are some of them. With the development of biotechnology and molecular biology, the production of hyperlignolytic mutants by genetic modification of wild-type species is one approach that could be studied further. Furthermore, complete understanding of the theoretical basis behind the mechanisms of actions of these hydrolytic enzyme systems is very useful in the process of enhancing hydrolytic efficiency.
\nVarious process parameters affecting biological pretreatment like incubation temperature, incubation time, inoculums concentration, moisture, aeration, and conditions of pH have to be optimized. This must be done with well-planned laboratory-scale experiments. It is essential to pay attention to the microorganism used as well as the type of lignocellulosic material utilized because these parameters obviously change based on these two factors. Accessory enzymes are those enzymes which act on less abundant linkages found in plant cell walls. These include arabinases, lyases, pectinases, galactanases, and several types of esterases. Some studies have reported that addition of these accessory enzymes will improve hydrolysis efficiency.
\nRecently, several studies have been conducted in Sri Lanka on efficient lignocellulose-degrading microorganisms isolated from the natural environment. The effect of coculturing these fungal isolates for degradation of lignocellulosic material has also been reported. Coculturing of Trichoderma spp. with other cellulolytic fungi has found to improve the activity of lignocellulose-degrading enzymes compared to its monocultures [36]. In a different study, 18 basidiomycete isolates from the natural environment of Sri Lanka has been evaluated for their lignocellulose-degrading enzyme production. An Earliella scabrosa species with higher laccase activity (79,600 U/l) when cultured in 50 g/l rice bran has been reported [37]. Thus, it can potentially be used for industrial production of laccase using rice bran as a cheap carbon source for high laccase production.
\nThe current progress in applications of cellulases is truly remarkable and attracting worldwide attention. It has already conquered the global market in an unbeatable way. Microbes are an attractive topic of interest for the production of cellulases due to their immense potential for cellulase production. However, it is apparent that more efficient species are still out there in the environment unnoticed by researchers. Further exploration and understanding of hidden mechanisms behind the activity of these enzymes are much more important. Microbial cellulases are preferred for their potential applications in a broad range of industries. Their ventures are expanding day by day. More and more researches are required to produce scientific knowledge to meet the growing demands for microbial cellulase. The advances in the emerging fields such as biotechnology, microbiology, and molecular biology will open up novel strategies to magnify the still-unlocked potentials of these enzymes. Eventually, it will be able to fine-tune the areas which still are dragging on the way to their utmost success.
\nSpecial thanks go to Research Assistant, Mr. K. Mohanan and Technical Officer Mrs. Kumuduni Karunarathna at Bioenergy and Soil Ecosystems Research Project, National Institute of Fundamental Studies, Kandy Sri Lanka and the National Research Council (Grant No: 12-021) for financial support.
\nNo conflicts of interest.
\nUnsubscribe unsuccessful, no matching records found in our database.
",metaTitle:"Unsubscribe Unsuccessful",metaDescription:"Unsubscribe unsuccessful, no matching records found in our database.",metaKeywords:null,canonicalURL:"/page/unsubscribe-unsuccessful",contentRaw:'[{"type":"htmlEditorComponent","content":""}]'},components:[{type:"htmlEditorComponent",content:""}]},successStories:{items:[]},authorsAndEditors:{filterParams:{sort:"featured,name"},profiles:[{id:"6700",title:"Dr.",name:"Abbass A.",middleName:null,surname:"Hashim",slug:"abbass-a.-hashim",fullName:"Abbass A. Hashim",position:null,profilePictureURL:"https://mts.intechopen.com/storage/users/6700/images/1864_n.jpg",biography:"Currently I am carrying out research in several areas of interest, mainly covering work on chemical and bio-sensors, semiconductor thin film device fabrication and characterisation.\nAt the moment I have very strong interest in radiation environmental pollution and bacteriology treatment. The teams of researchers are working very hard to bring novel results in this field. I am also a member of the team in charge for the supervision of Ph.D. students in the fields of development of silicon based planar waveguide sensor devices, study of inelastic electron tunnelling in planar tunnelling nanostructures for sensing applications and development of organotellurium(IV) compounds for semiconductor applications. I am a specialist in data analysis techniques and nanosurface structure. I have served as the editor for many books, been a member of the editorial board in science journals, have published many papers and hold many patents.",institutionString:null,institution:{name:"Sheffield Hallam University",country:{name:"United Kingdom"}}},{id:"54525",title:"Prof.",name:"Abdul Latif",middleName:null,surname:"Ahmad",slug:"abdul-latif-ahmad",fullName:"Abdul Latif Ahmad",position:null,profilePictureURL:"//cdnintech.com/web/frontend/www/assets/author.svg",biography:null,institutionString:null,institution:null},{id:"20567",title:"Prof.",name:"Ado",middleName:null,surname:"Jorio",slug:"ado-jorio",fullName:"Ado Jorio",position:null,profilePictureURL:"//cdnintech.com/web/frontend/www/assets/author.svg",biography:null,institutionString:null,institution:{name:"Universidade Federal de Minas Gerais",country:{name:"Brazil"}}},{id:"47940",title:"Dr.",name:"Alberto",middleName:null,surname:"Mantovani",slug:"alberto-mantovani",fullName:"Alberto Mantovani",position:null,profilePictureURL:"//cdnintech.com/web/frontend/www/assets/author.svg",biography:null,institutionString:null,institution:null},{id:"12392",title:"Mr.",name:"Alex",middleName:null,surname:"Lazinica",slug:"alex-lazinica",fullName:"Alex Lazinica",position:null,profilePictureURL:"https://mts.intechopen.com/storage/users/12392/images/7282_n.png",biography:"Alex Lazinica is the founder and CEO of IntechOpen. After obtaining a Master's degree in Mechanical Engineering, he continued his PhD studies in Robotics at the Vienna University of Technology. Here he worked as a robotic researcher with the university's Intelligent Manufacturing Systems Group as well as a guest researcher at various European universities, including the Swiss Federal Institute of Technology Lausanne (EPFL). During this time he published more than 20 scientific papers, gave presentations, served as a reviewer for major robotic journals and conferences and most importantly he co-founded and built the International Journal of Advanced Robotic Systems- world's first Open Access journal in the field of robotics. Starting this journal was a pivotal point in his career, since it was a pathway to founding IntechOpen - Open Access publisher focused on addressing academic researchers needs. Alex is a personification of IntechOpen key values being trusted, open and entrepreneurial. Today his focus is on defining the growth and development strategy for the company.",institutionString:null,institution:{name:"TU Wien",country:{name:"Austria"}}},{id:"19816",title:"Prof.",name:"Alexander",middleName:null,surname:"Kokorin",slug:"alexander-kokorin",fullName:"Alexander Kokorin",position:null,profilePictureURL:"https://mts.intechopen.com/storage/users/19816/images/1607_n.jpg",biography:"Alexander I. Kokorin: born: 1947, Moscow; DSc., PhD; Principal Research Fellow (Research Professor) of Department of Kinetics and Catalysis, N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow.\r\nArea of research interests: physical chemistry of complex-organized molecular and nanosized systems, including polymer-metal complexes; the surface of doped oxide semiconductors. He is an expert in structural, absorptive, catalytic and photocatalytic properties, in structural organization and dynamic features of ionic liquids, in magnetic interactions between paramagnetic centers. The author or co-author of 3 books, over 200 articles and reviews in scientific journals and books. He is an actual member of the International EPR/ESR Society, European Society on Quantum Solar Energy Conversion, Moscow House of Scientists, of the Board of Moscow Physical Society.",institutionString:null,institution:{name:"Semenov Institute of Chemical Physics",country:{name:"Russia"}}},{id:"62389",title:"PhD.",name:"Ali Demir",middleName:null,surname:"Sezer",slug:"ali-demir-sezer",fullName:"Ali Demir Sezer",position:null,profilePictureURL:"https://mts.intechopen.com/storage/users/62389/images/3413_n.jpg",biography:"Dr. Ali Demir Sezer has a Ph.D. from Pharmaceutical Biotechnology at the Faculty of Pharmacy, University of Marmara (Turkey). He is the member of many Pharmaceutical Associations and acts as a reviewer of scientific journals and European projects under different research areas such as: drug delivery systems, nanotechnology and pharmaceutical biotechnology. Dr. Sezer is the author of many scientific publications in peer-reviewed journals and poster communications. Focus of his research activity is drug delivery, physico-chemical characterization and biological evaluation of biopolymers micro and nanoparticles as modified drug delivery system, and colloidal drug carriers (liposomes, nanoparticles etc.).",institutionString:null,institution:{name:"Marmara University",country:{name:"Turkey"}}},{id:"61051",title:"Prof.",name:"Andrea",middleName:null,surname:"Natale",slug:"andrea-natale",fullName:"Andrea Natale",position:null,profilePictureURL:"//cdnintech.com/web/frontend/www/assets/author.svg",biography:null,institutionString:null,institution:null},{id:"100762",title:"Prof.",name:"Andrea",middleName:null,surname:"Natale",slug:"andrea-natale",fullName:"Andrea Natale",position:null,profilePictureURL:"//cdnintech.com/web/frontend/www/assets/author.svg",biography:null,institutionString:null,institution:{name:"St David's Medical Center",country:{name:"United States of America"}}},{id:"107416",title:"Dr.",name:"Andrea",middleName:null,surname:"Natale",slug:"andrea-natale",fullName:"Andrea Natale",position:null,profilePictureURL:"//cdnintech.com/web/frontend/www/assets/author.svg",biography:null,institutionString:null,institution:{name:"Texas Cardiac Arrhythmia",country:{name:"United States of America"}}},{id:"64434",title:"Dr.",name:"Angkoon",middleName:null,surname:"Phinyomark",slug:"angkoon-phinyomark",fullName:"Angkoon Phinyomark",position:null,profilePictureURL:"https://mts.intechopen.com/storage/users/64434/images/2619_n.jpg",biography:"My name is Angkoon Phinyomark. I received a B.Eng. degree in Computer Engineering with First Class Honors in 2008 from Prince of Songkla University, Songkhla, Thailand, where I received a Ph.D. degree in Electrical Engineering. My research interests are primarily in the area of biomedical signal processing and classification notably EMG (electromyography signal), EOG (electrooculography signal), and EEG (electroencephalography signal), image analysis notably breast cancer analysis and optical coherence tomography, and rehabilitation engineering. I became a student member of IEEE in 2008. During October 2011-March 2012, I had worked at School of Computer Science and Electronic Engineering, University of Essex, Colchester, Essex, United Kingdom. In addition, during a B.Eng. I had been a visiting research student at Faculty of Computer Science, University of Murcia, Murcia, Spain for three months.\n\nI have published over 40 papers during 5 years in refereed journals, books, and conference proceedings in the areas of electro-physiological signals processing and classification, notably EMG and EOG signals, fractal analysis, wavelet analysis, texture analysis, feature extraction and machine learning algorithms, and assistive and rehabilitative devices. I have several computer programming language certificates, i.e. Sun Certified Programmer for the Java 2 Platform 1.4 (SCJP), Microsoft Certified Professional Developer, Web Developer (MCPD), Microsoft Certified Technology Specialist, .NET Framework 2.0 Web (MCTS). I am a Reviewer for several refereed journals and international conferences, such as IEEE Transactions on Biomedical Engineering, IEEE Transactions on Industrial Electronics, Optic Letters, Measurement Science Review, and also a member of the International Advisory Committee for 2012 IEEE Business Engineering and Industrial Applications and 2012 IEEE Symposium on Business, Engineering and Industrial Applications.",institutionString:null,institution:{name:"Joseph Fourier University",country:{name:"France"}}},{id:"55578",title:"Dr.",name:"Antonio",middleName:null,surname:"Jurado-Navas",slug:"antonio-jurado-navas",fullName:"Antonio Jurado-Navas",position:null,profilePictureURL:"https://mts.intechopen.com/storage/users/55578/images/4574_n.png",biography:"Antonio Jurado-Navas received the M.S. degree (2002) and the Ph.D. degree (2009) in Telecommunication Engineering, both from the University of Málaga (Spain). He first worked as a consultant at Vodafone-Spain. From 2004 to 2011, he was a Research Assistant with the Communications Engineering Department at the University of Málaga. In 2011, he became an Assistant Professor in the same department. From 2012 to 2015, he was with Ericsson Spain, where he was working on geo-location\ntools for third generation mobile networks. Since 2015, he is a Marie-Curie fellow at the Denmark Technical University. His current research interests include the areas of mobile communication systems and channel modeling in addition to atmospheric optical communications, adaptive optics and statistics",institutionString:null,institution:{name:"University of Malaga",country:{name:"Spain"}}}],filtersByRegion:[{group:"region",caption:"North America",value:1,count:5698},{group:"region",caption:"Middle and South America",value:2,count:5172},{group:"region",caption:"Africa",value:3,count:1689},{group:"region",caption:"Asia",value:4,count:10244},{group:"region",caption:"Australia and Oceania",value:5,count:888},{group:"region",caption:"Europe",value:6,count:15650}],offset:12,limit:12,total:117315},chapterEmbeded:{data:{}},editorApplication:{success:null,errors:{}},ofsBooks:{filterParams:{topicId:"20"},books:[{type:"book",id:"10206",title:"Terahertz Technology",subtitle:null,isOpenForSubmission:!0,hash:"2cdb79bf6297623f1d6202ef11f099c4",slug:null,bookSignature:"Dr. Borwen You and Dr. Ja-Yu Lu",coverURL:"https://cdn.intechopen.com/books/images_new/10206.jpg",editedByType:null,editors:[{id:"191131",title:"Dr.",name:"Borwen",surname:"You",slug:"borwen-you",fullName:"Borwen You"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10575",title:"Magnetic Skyrmions",subtitle:null,isOpenForSubmission:!0,hash:"d93d7485e8a6a30d9e069aed78fdb355",slug:null,bookSignature:"Prof. Dipti Ranjan Sahu",coverURL:"https://cdn.intechopen.com/books/images_new/10575.jpg",editedByType:null,editors:[{id:"251855",title:"Prof.",name:"Dipti Ranjan",surname:"Sahu",slug:"dipti-ranjan-sahu",fullName:"Dipti Ranjan Sahu"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10675",title:"Hydrostatics",subtitle:null,isOpenForSubmission:!0,hash:"c86c2fa9f835d4ad5e7efd8b01921866",slug:null,bookSignature:"",coverURL:"https://cdn.intechopen.com/books/images_new/10675.jpg",editedByType:null,editors:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10957",title:"Liquid Crystals",subtitle:null,isOpenForSubmission:!0,hash:"b8dac1788dc54d12f8fc3d94a7e3e338",slug:null,bookSignature:"",coverURL:"//cdnintech.com/web/frontend/www/assets/cover.jpg",editedByType:null,editors:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}}],filtersByTopic:[{group:"topic",caption:"Agricultural and Biological Sciences",value:5,count:9},{group:"topic",caption:"Biochemistry, Genetics and Molecular Biology",value:6,count:16},{group:"topic",caption:"Business, Management and Economics",value:7,count:2},{group:"topic",caption:"Chemistry",value:8,count:6},{group:"topic",caption:"Computer and Information Science",value:9,count:10},{group:"topic",caption:"Earth and Planetary Sciences",value:10,count:4},{group:"topic",caption:"Engineering",value:11,count:15},{group:"topic",caption:"Environmental Sciences",value:12,count:2},{group:"topic",caption:"Immunology and Microbiology",value:13,count:4},{group:"topic",caption:"Materials Science",value:14,count:4},{group:"topic",caption:"Mathematics",value:15,count:1},{group:"topic",caption:"Medicine",value:16,count:56},{group:"topic",caption:"Neuroscience",value:18,count:1},{group:"topic",caption:"Pharmacology, Toxicology and Pharmaceutical Science",value:19,count:6},{group:"topic",caption:"Physics",value:20,count:2},{group:"topic",caption:"Psychology",value:21,count:3},{group:"topic",caption:"Robotics",value:22,count:1},{group:"topic",caption:"Social Sciences",value:23,count:3},{group:"topic",caption:"Technology",value:24,count:1},{group:"topic",caption:"Veterinary Medicine and Science",value:25,count:2}],offset:12,limit:12,total:4},popularBooks:{featuredBooks:[{type:"book",id:"7802",title:"Modern Slavery and Human Trafficking",subtitle:null,isOpenForSubmission:!1,hash:"587a0b7fb765f31cc98de33c6c07c2e0",slug:"modern-slavery-and-human-trafficking",bookSignature:"Jane Reeves",coverURL:"https://cdn.intechopen.com/books/images_new/7802.jpg",editors:[{id:"211328",title:"Prof.",name:"Jane",middleName:null,surname:"Reeves",slug:"jane-reeves",fullName:"Jane Reeves"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"8545",title:"Animal Reproduction in Veterinary Medicine",subtitle:null,isOpenForSubmission:!1,hash:"13aaddf5fdbbc78387e77a7da2388bf6",slug:"animal-reproduction-in-veterinary-medicine",bookSignature:"Faruk Aral, Rita Payan-Carreira and Miguel Quaresma",coverURL:"https://cdn.intechopen.com/books/images_new/8545.jpg",editors:[{id:"25600",title:"Prof.",name:"Faruk",middleName:null,surname:"Aral",slug:"faruk-aral",fullName:"Faruk Aral"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9961",title:"Data Mining",subtitle:"Methods, Applications and Systems",isOpenForSubmission:!1,hash:"ed79fb6364f2caf464079f94a0387146",slug:"data-mining-methods-applications-and-systems",bookSignature:"Derya Birant",coverURL:"https://cdn.intechopen.com/books/images_new/9961.jpg",editors:[{id:"15609",title:"Dr.",name:"Derya",middleName:null,surname:"Birant",slug:"derya-birant",fullName:"Derya Birant"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9157",title:"Neurodegenerative Diseases",subtitle:"Molecular Mechanisms and Current Therapeutic Approaches",isOpenForSubmission:!1,hash:"bc8be577966ef88735677d7e1e92ed28",slug:"neurodegenerative-diseases-molecular-mechanisms-and-current-therapeutic-approaches",bookSignature:"Nagehan Ersoy Tunalı",coverURL:"https://cdn.intechopen.com/books/images_new/9157.jpg",editors:[{id:"82778",title:"Ph.D.",name:"Nagehan",middleName:null,surname:"Ersoy Tunalı",slug:"nagehan-ersoy-tunali",fullName:"Nagehan Ersoy Tunalı"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"8686",title:"Direct Torque Control Strategies of Electrical Machines",subtitle:null,isOpenForSubmission:!1,hash:"b6ad22b14db2b8450228545d3d4f6b1a",slug:"direct-torque-control-strategies-of-electrical-machines",bookSignature:"Fatma Ben Salem",coverURL:"https://cdn.intechopen.com/books/images_new/8686.jpg",editors:[{id:"295623",title:"Associate Prof.",name:"Fatma",middleName:null,surname:"Ben Salem",slug:"fatma-ben-salem",fullName:"Fatma Ben Salem"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"7434",title:"Molecular Biotechnology",subtitle:null,isOpenForSubmission:!1,hash:"eceede809920e1ec7ecadd4691ede2ec",slug:"molecular-biotechnology",bookSignature:"Sergey Sedykh",coverURL:"https://cdn.intechopen.com/books/images_new/7434.jpg",editors:[{id:"178316",title:"Ph.D.",name:"Sergey",middleName:null,surname:"Sedykh",slug:"sergey-sedykh",fullName:"Sergey Sedykh"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9839",title:"Outdoor Recreation",subtitle:"Physiological and Psychological Effects on Health",isOpenForSubmission:!1,hash:"5f5a0d64267e32567daffa5b0c6a6972",slug:"outdoor-recreation-physiological-and-psychological-effects-on-health",bookSignature:"Hilde G. Nielsen",coverURL:"https://cdn.intechopen.com/books/images_new/9839.jpg",editors:[{id:"158692",title:"Ph.D.",name:"Hilde G.",middleName:null,surname:"Nielsen",slug:"hilde-g.-nielsen",fullName:"Hilde G. Nielsen"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9208",title:"Welding",subtitle:"Modern Topics",isOpenForSubmission:!1,hash:"7d6be076ccf3a3f8bd2ca52d86d4506b",slug:"welding-modern-topics",bookSignature:"Sadek Crisóstomo Absi Alfaro, Wojciech Borek and Błażej Tomiczek",coverURL:"https://cdn.intechopen.com/books/images_new/9208.jpg",editors:[{id:"65292",title:"Prof.",name:"Sadek Crisostomo Absi",middleName:"C. Absi",surname:"Alfaro",slug:"sadek-crisostomo-absi-alfaro",fullName:"Sadek Crisostomo Absi Alfaro"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9139",title:"Topics in Primary Care Medicine",subtitle:null,isOpenForSubmission:!1,hash:"ea774a4d4c1179da92a782e0ae9cde92",slug:"topics-in-primary-care-medicine",bookSignature:"Thomas F. Heston",coverURL:"https://cdn.intechopen.com/books/images_new/9139.jpg",editors:[{id:"217926",title:"Dr.",name:"Thomas F.",middleName:null,surname:"Heston",slug:"thomas-f.-heston",fullName:"Thomas F. Heston"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9343",title:"Trace Metals in the Environment",subtitle:"New Approaches and Recent Advances",isOpenForSubmission:!1,hash:"ae07e345bc2ce1ebbda9f70c5cd12141",slug:"trace-metals-in-the-environment-new-approaches-and-recent-advances",bookSignature:"Mario Alfonso Murillo-Tovar, Hugo Saldarriaga-Noreña and Agnieszka Saeid",coverURL:"https://cdn.intechopen.com/books/images_new/9343.jpg",editors:[{id:"255959",title:"Dr.",name:"Mario Alfonso",middleName:null,surname:"Murillo-Tovar",slug:"mario-alfonso-murillo-tovar",fullName:"Mario Alfonso Murillo-Tovar"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"8697",title:"Virtual Reality and Its Application in Education",subtitle:null,isOpenForSubmission:!1,hash:"ee01b5e387ba0062c6b0d1e9227bda05",slug:"virtual-reality-and-its-application-in-education",bookSignature:"Dragan Cvetković",coverURL:"https://cdn.intechopen.com/books/images_new/8697.jpg",editors:[{id:"101330",title:"Dr.",name:"Dragan",middleName:"Mladen",surname:"Cvetković",slug:"dragan-cvetkovic",fullName:"Dragan Cvetković"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"7831",title:"Sustainability in Urban Planning and Design",subtitle:null,isOpenForSubmission:!1,hash:"c924420492c8c2c9751e178d025f4066",slug:"sustainability-in-urban-planning-and-design",bookSignature:"Amjad Almusaed, Asaad Almssad and Linh Truong - Hong",coverURL:"https://cdn.intechopen.com/books/images_new/7831.jpg",editors:[{id:"110471",title:"Dr.",name:"Amjad",middleName:"Zaki",surname:"Almusaed",slug:"amjad-almusaed",fullName:"Amjad Almusaed"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}}],offset:12,limit:12,total:5143},hotBookTopics:{hotBooks:[],offset:0,limit:12,total:null},publish:{},publishingProposal:{success:null,errors:{}},books:{featuredBooks:[{type:"book",id:"9208",title:"Welding",subtitle:"Modern Topics",isOpenForSubmission:!1,hash:"7d6be076ccf3a3f8bd2ca52d86d4506b",slug:"welding-modern-topics",bookSignature:"Sadek Crisóstomo Absi Alfaro, Wojciech Borek and Błażej Tomiczek",coverURL:"https://cdn.intechopen.com/books/images_new/9208.jpg",editors:[{id:"65292",title:"Prof.",name:"Sadek Crisostomo Absi",middleName:"C. Absi",surname:"Alfaro",slug:"sadek-crisostomo-absi-alfaro",fullName:"Sadek Crisostomo Absi Alfaro"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9139",title:"Topics in Primary Care Medicine",subtitle:null,isOpenForSubmission:!1,hash:"ea774a4d4c1179da92a782e0ae9cde92",slug:"topics-in-primary-care-medicine",bookSignature:"Thomas F. Heston",coverURL:"https://cdn.intechopen.com/books/images_new/9139.jpg",editors:[{id:"217926",title:"Dr.",name:"Thomas F.",middleName:null,surname:"Heston",slug:"thomas-f.-heston",fullName:"Thomas F. Heston"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"8697",title:"Virtual Reality and Its Application in Education",subtitle:null,isOpenForSubmission:!1,hash:"ee01b5e387ba0062c6b0d1e9227bda05",slug:"virtual-reality-and-its-application-in-education",bookSignature:"Dragan Cvetković",coverURL:"https://cdn.intechopen.com/books/images_new/8697.jpg",editors:[{id:"101330",title:"Dr.",name:"Dragan",middleName:"Mladen",surname:"Cvetković",slug:"dragan-cvetkovic",fullName:"Dragan Cvetković"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9343",title:"Trace Metals in the Environment",subtitle:"New Approaches and Recent Advances",isOpenForSubmission:!1,hash:"ae07e345bc2ce1ebbda9f70c5cd12141",slug:"trace-metals-in-the-environment-new-approaches-and-recent-advances",bookSignature:"Mario Alfonso Murillo-Tovar, Hugo Saldarriaga-Noreña and Agnieszka Saeid",coverURL:"https://cdn.intechopen.com/books/images_new/9343.jpg",editors:[{id:"255959",title:"Dr.",name:"Mario Alfonso",middleName:null,surname:"Murillo-Tovar",slug:"mario-alfonso-murillo-tovar",fullName:"Mario Alfonso Murillo-Tovar"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9785",title:"Endometriosis",subtitle:null,isOpenForSubmission:!1,hash:"f457ca61f29cf7e8bc191732c50bb0ce",slug:"endometriosis",bookSignature:"Courtney Marsh",coverURL:"https://cdn.intechopen.com/books/images_new/9785.jpg",editors:[{id:"255491",title:"Dr.",name:"Courtney",middleName:null,surname:"Marsh",slug:"courtney-marsh",fullName:"Courtney Marsh"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"7831",title:"Sustainability in Urban Planning and Design",subtitle:null,isOpenForSubmission:!1,hash:"c924420492c8c2c9751e178d025f4066",slug:"sustainability-in-urban-planning-and-design",bookSignature:"Amjad Almusaed, Asaad Almssad and Linh Truong - Hong",coverURL:"https://cdn.intechopen.com/books/images_new/7831.jpg",editors:[{id:"110471",title:"Dr.",name:"Amjad",middleName:"Zaki",surname:"Almusaed",slug:"amjad-almusaed",fullName:"Amjad Almusaed"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9376",title:"Contemporary Developments and Perspectives in International Health Security",subtitle:"Volume 1",isOpenForSubmission:!1,hash:"b9a00b84cd04aae458fb1d6c65795601",slug:"contemporary-developments-and-perspectives-in-international-health-security-volume-1",bookSignature:"Stanislaw P. Stawicki, Michael S. Firstenberg, Sagar C. Galwankar, Ricardo Izurieta and Thomas Papadimos",coverURL:"https://cdn.intechopen.com/books/images_new/9376.jpg",editors:[{id:"181694",title:"Dr.",name:"Stanislaw P.",middleName:null,surname:"Stawicki",slug:"stanislaw-p.-stawicki",fullName:"Stanislaw P. Stawicki"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"7769",title:"Medical Isotopes",subtitle:null,isOpenForSubmission:!1,hash:"f8d3c5a6c9a42398e56b4e82264753f7",slug:"medical-isotopes",bookSignature:"Syed Ali Raza Naqvi and Muhammad Babar Imrani",coverURL:"https://cdn.intechopen.com/books/images_new/7769.jpg",editors:[{id:"259190",title:"Dr.",name:"Syed Ali Raza",middleName:null,surname:"Naqvi",slug:"syed-ali-raza-naqvi",fullName:"Syed Ali Raza Naqvi"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9279",title:"Concepts, Applications and Emerging Opportunities in Industrial Engineering",subtitle:null,isOpenForSubmission:!1,hash:"9bfa87f9b627a5468b7c1e30b0eea07a",slug:"concepts-applications-and-emerging-opportunities-in-industrial-engineering",bookSignature:"Gary Moynihan",coverURL:"https://cdn.intechopen.com/books/images_new/9279.jpg",editors:[{id:"16974",title:"Dr.",name:"Gary",middleName:null,surname:"Moynihan",slug:"gary-moynihan",fullName:"Gary Moynihan"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"7807",title:"A Closer Look at Organizational Culture in Action",subtitle:null,isOpenForSubmission:!1,hash:"05c608b9271cc2bc711f4b28748b247b",slug:"a-closer-look-at-organizational-culture-in-action",bookSignature:"Süleyman Davut Göker",coverURL:"https://cdn.intechopen.com/books/images_new/7807.jpg",editors:[{id:"190035",title:"Associate Prof.",name:"Süleyman Davut",middleName:null,surname:"Göker",slug:"suleyman-davut-goker",fullName:"Süleyman Davut Göker"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}}],latestBooks:[{type:"book",id:"7434",title:"Molecular Biotechnology",subtitle:null,isOpenForSubmission:!1,hash:"eceede809920e1ec7ecadd4691ede2ec",slug:"molecular-biotechnology",bookSignature:"Sergey Sedykh",coverURL:"https://cdn.intechopen.com/books/images_new/7434.jpg",editedByType:"Edited by",editors:[{id:"178316",title:"Ph.D.",name:"Sergey",middleName:null,surname:"Sedykh",slug:"sergey-sedykh",fullName:"Sergey Sedykh"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"8545",title:"Animal Reproduction in Veterinary Medicine",subtitle:null,isOpenForSubmission:!1,hash:"13aaddf5fdbbc78387e77a7da2388bf6",slug:"animal-reproduction-in-veterinary-medicine",bookSignature:"Faruk Aral, Rita Payan-Carreira and Miguel Quaresma",coverURL:"https://cdn.intechopen.com/books/images_new/8545.jpg",editedByType:"Edited by",editors:[{id:"25600",title:"Prof.",name:"Faruk",middleName:null,surname:"Aral",slug:"faruk-aral",fullName:"Faruk Aral"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"9569",title:"Methods in Molecular Medicine",subtitle:null,isOpenForSubmission:!1,hash:"691d3f3c4ac25a8093414e9b270d2843",slug:"methods-in-molecular-medicine",bookSignature:"Yusuf Tutar",coverURL:"https://cdn.intechopen.com/books/images_new/9569.jpg",editedByType:"Edited by",editors:[{id:"158492",title:"Prof.",name:"Yusuf",middleName:null,surname:"Tutar",slug:"yusuf-tutar",fullName:"Yusuf Tutar"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"9839",title:"Outdoor Recreation",subtitle:"Physiological and Psychological Effects on Health",isOpenForSubmission:!1,hash:"5f5a0d64267e32567daffa5b0c6a6972",slug:"outdoor-recreation-physiological-and-psychological-effects-on-health",bookSignature:"Hilde G. Nielsen",coverURL:"https://cdn.intechopen.com/books/images_new/9839.jpg",editedByType:"Edited by",editors:[{id:"158692",title:"Ph.D.",name:"Hilde G.",middleName:null,surname:"Nielsen",slug:"hilde-g.-nielsen",fullName:"Hilde G. Nielsen"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"7802",title:"Modern Slavery and Human Trafficking",subtitle:null,isOpenForSubmission:!1,hash:"587a0b7fb765f31cc98de33c6c07c2e0",slug:"modern-slavery-and-human-trafficking",bookSignature:"Jane Reeves",coverURL:"https://cdn.intechopen.com/books/images_new/7802.jpg",editedByType:"Edited by",editors:[{id:"211328",title:"Prof.",name:"Jane",middleName:null,surname:"Reeves",slug:"jane-reeves",fullName:"Jane Reeves"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"8063",title:"Food Security in Africa",subtitle:null,isOpenForSubmission:!1,hash:"8cbf3d662b104d19db2efc9d59249efc",slug:"food-security-in-africa",bookSignature:"Barakat Mahmoud",coverURL:"https://cdn.intechopen.com/books/images_new/8063.jpg",editedByType:"Edited by",editors:[{id:"92016",title:"Dr.",name:"Barakat",middleName:null,surname:"Mahmoud",slug:"barakat-mahmoud",fullName:"Barakat Mahmoud"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10118",title:"Plant Stress Physiology",subtitle:null,isOpenForSubmission:!1,hash:"c68b09d2d2634fc719ae3b9a64a27839",slug:"plant-stress-physiology",bookSignature:"Akbar Hossain",coverURL:"https://cdn.intechopen.com/books/images_new/10118.jpg",editedByType:"Edited by",editors:[{id:"280755",title:"Dr.",name:"Akbar",middleName:null,surname:"Hossain",slug:"akbar-hossain",fullName:"Akbar Hossain"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"9157",title:"Neurodegenerative Diseases",subtitle:"Molecular Mechanisms and Current Therapeutic Approaches",isOpenForSubmission:!1,hash:"bc8be577966ef88735677d7e1e92ed28",slug:"neurodegenerative-diseases-molecular-mechanisms-and-current-therapeutic-approaches",bookSignature:"Nagehan Ersoy Tunalı",coverURL:"https://cdn.intechopen.com/books/images_new/9157.jpg",editedByType:"Edited by",editors:[{id:"82778",title:"Ph.D.",name:"Nagehan",middleName:null,surname:"Ersoy Tunalı",slug:"nagehan-ersoy-tunali",fullName:"Nagehan Ersoy Tunalı"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"9961",title:"Data Mining",subtitle:"Methods, Applications and Systems",isOpenForSubmission:!1,hash:"ed79fb6364f2caf464079f94a0387146",slug:"data-mining-methods-applications-and-systems",bookSignature:"Derya Birant",coverURL:"https://cdn.intechopen.com/books/images_new/9961.jpg",editedByType:"Edited by",editors:[{id:"15609",title:"Dr.",name:"Derya",middleName:null,surname:"Birant",slug:"derya-birant",fullName:"Derya Birant"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"8686",title:"Direct Torque Control Strategies of Electrical Machines",subtitle:null,isOpenForSubmission:!1,hash:"b6ad22b14db2b8450228545d3d4f6b1a",slug:"direct-torque-control-strategies-of-electrical-machines",bookSignature:"Fatma Ben Salem",coverURL:"https://cdn.intechopen.com/books/images_new/8686.jpg",editedByType:"Edited by",editors:[{id:"295623",title:"Associate Prof.",name:"Fatma",middleName:null,surname:"Ben Salem",slug:"fatma-ben-salem",fullName:"Fatma Ben Salem"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}}]},subject:{topic:{id:"754",title:"Optical Engineering",slug:"optical-engineering",parent:{title:"Electrical and Electronic Engineering",slug:"electrical-and-electronic-engineering"},numberOfBooks:22,numberOfAuthorsAndEditors:677,numberOfWosCitations:1213,numberOfCrossrefCitations:566,numberOfDimensionsCitations:1187,videoUrl:null,fallbackUrl:null,description:null},booksByTopicFilter:{topicSlug:"optical-engineering",sort:"-publishedDate",limit:12,offset:0},booksByTopicCollection:[{type:"book",id:"5074",title:"Some Advanced Functionalities of Optical Amplifiers",subtitle:null,isOpenForSubmission:!1,hash:"7c7a6a4771c3ed374faf640de9d0ba50",slug:"some-advanced-functionalities-of-optical-amplifiers",bookSignature:"Sisir Kumar Garai",coverURL:"https://cdn.intechopen.com/books/images_new/5074.jpg",editedByType:"Edited by",editors:[{id:"113477",title:"Dr.",name:"Sisir",middleName:"Kumar",surname:"Garai",slug:"sisir-garai",fullName:"Sisir Garai"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"4607",title:"Optoelectronics",subtitle:"Materials and Devices",isOpenForSubmission:!1,hash:"0e72724ec0d3faf1ec705cb92fa03c32",slug:"optoelectronics-materials-and-devices",bookSignature:"Sergei L. Pyshkin and John Ballato",coverURL:"https://cdn.intechopen.com/books/images_new/4607.jpg",editedByType:"Edited by",editors:[{id:"43016",title:"Prof.",name:"Sergei",middleName:"L.",surname:"Pyshkin",slug:"sergei-pyshkin",fullName:"Sergei Pyshkin"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"4506",title:"Advances in Optical Fiber Technology",subtitle:"Fundamental Optical Phenomena and Applications",isOpenForSubmission:!1,hash:"9db9536cfa0ac3a32647a40c763b0b2d",slug:"advances-in-optical-fiber-technology-fundamental-optical-phenomena-and-applications",bookSignature:"Moh Yasin, Hamzah Arof and Sulaiman Wadi Harun",coverURL:"https://cdn.intechopen.com/books/images_new/4506.jpg",editedByType:"Edited by",editors:[{id:"294347",title:"Dr.",name:"Moh",middleName:null,surname:"Yasin",slug:"moh-yasin",fullName:"Moh Yasin"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"4494",title:"Advances in Optical Communication",subtitle:null,isOpenForSubmission:!1,hash:"8cd5ba4d56db55598d255b1d4f9e9519",slug:"advances-in-optical-communication",bookSignature:"Narottam Das",coverURL:"https://cdn.intechopen.com/books/images_new/4494.jpg",editedByType:"Edited by",editors:[{id:"15357",title:"Dr.",name:"Narottam",middleName:null,surname:"Das",slug:"narottam-das",fullName:"Narottam Das"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3849",title:"Optical Sensors",subtitle:"New Developments and Practical Applications",isOpenForSubmission:!1,hash:"951a7c0782d0f39b6aeef2c4a7b89846",slug:"optical-sensors-new-developments-and-practical-applications",bookSignature:"Mohamad Yasin, Sulaiman Wadi Harun and Hamzah Arof",coverURL:"https://cdn.intechopen.com/books/images_new/3849.jpg",editedByType:"Edited by",editors:[{id:"294347",title:"Dr.",name:"Moh",middleName:null,surname:"Yasin",slug:"moh-yasin",fullName:"Moh Yasin"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3360",title:"Current Developments in Optical Fiber Technology",subtitle:null,isOpenForSubmission:!1,hash:"834b9a9593a62b116d2101815fd94dd3",slug:"current-developments-in-optical-fiber-technology",bookSignature:"Sulaiman Wadi Harun and Hamzah Arof",coverURL:"https://cdn.intechopen.com/books/images_new/3360.jpg",editedByType:"Edited by",editors:[{id:"17617",title:"Dr.",name:"Sulaiman Wadi",middleName:null,surname:"Harun",slug:"sulaiman-wadi-harun",fullName:"Sulaiman Wadi Harun"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"2992",title:"Current Trends in Short- and Long-period Fiber Gratings",subtitle:null,isOpenForSubmission:!1,hash:"7ea3b8fc542d07312526928ba5bac062",slug:"current-trends-in-short-and-long-period-fiber-gratings",bookSignature:"Christian Cuadrado-Laborde",coverURL:"https://cdn.intechopen.com/books/images_new/2992.jpg",editedByType:"Edited by",editors:[{id:"29543",title:"Dr.",name:"Christian",middleName:"A",surname:"Cuadrado-Laborde",slug:"christian-cuadrado-laborde",fullName:"Christian Cuadrado-Laborde"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"2196",title:"Organic Light Emitting Devices",subtitle:null,isOpenForSubmission:!1,hash:"a0752ca9019b034c7493b2c793e4e0cc",slug:"organic-light-emitting-devices",bookSignature:"Jai Singh",coverURL:"https://cdn.intechopen.com/books/images_new/2196.jpg",editedByType:"Edited by",editors:[{id:"148578",title:"Prof.",name:"Jai",middleName:null,surname:"Singh",slug:"jai-singh",fullName:"Jai Singh"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3068",title:"Solutions and Applications of Scattering, Propagation, Radiation and Emission of Electromagnetic Waves",subtitle:null,isOpenForSubmission:!1,hash:"ed32f8b9c79742d8ba52a7546781b4fb",slug:"solutions-and-applications-of-scattering-propagation-radiation-and-emission-of-electromagnetic-waves",bookSignature:"Ahmed Kishk",coverURL:"https://cdn.intechopen.com/books/images_new/3068.jpg",editedByType:"Edited by",editors:[{id:"73920",title:"Prof.",name:"Ahmed",middleName:"A",surname:"Kishk",slug:"ahmed-kishk",fullName:"Ahmed Kishk"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"2478",title:"Optical Communication",subtitle:null,isOpenForSubmission:!1,hash:"f8af14196b5429d6bf9fcb7db0a39199",slug:"optical-communication",bookSignature:"Narottam Das",coverURL:"https://cdn.intechopen.com/books/images_new/2478.jpg",editedByType:"Edited by",editors:[{id:"15357",title:"Dr.",name:"Narottam",middleName:null,surname:"Das",slug:"narottam-das",fullName:"Narottam Das"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"1383",title:"Laser Scanner Technology",subtitle:null,isOpenForSubmission:!1,hash:"771c3069cd4dc6212513566bc71c2e5e",slug:"laser-scanner-technology",bookSignature:"J. Apolinar Munoz Rodriguez",coverURL:"https://cdn.intechopen.com/books/images_new/1383.jpg",editedByType:"Edited by",editors:[{id:"108690",title:"Dr.",name:"J. Apolinar",middleName:null,surname:"Munoz Rodriguez",slug:"j.-apolinar-munoz-rodriguez",fullName:"J. Apolinar Munoz Rodriguez"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"1502",title:"Selected Topics on Optical Amplifiers in Present Scenario",subtitle:null,isOpenForSubmission:!1,hash:"fd2ecaaacdf0728e8f8af28d899ca791",slug:"selected-topics-on-optical-amplifiers-in-present-scenario",bookSignature:"Sisir Kumar Garai",coverURL:"https://cdn.intechopen.com/books/images_new/1502.jpg",editedByType:"Edited by",editors:[{id:"113477",title:"Dr.",name:"Sisir",middleName:"Kumar",surname:"Garai",slug:"sisir-garai",fullName:"Sisir Garai"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}}],booksByTopicTotal:22,mostCitedChapters:[{id:"8446",doi:"10.5772/39538",title:"2 µm Laser Sources and Their Possible Applications",slug:"2-m-laser-sources-and-their-possible-applications",totalDownloads:11307,totalCrossrefCites:97,totalDimensionsCites:141,book:{slug:"frontiers-in-guided-wave-optics-and-optoelectronics",title:"Frontiers in Guided Wave Optics and Optoelectronics",fullTitle:"Frontiers in Guided Wave Optics and Optoelectronics"},signatures:"Karsten Scholle, Samir Lamrini, Philipp Koopmann and Peter Fuhrberg",authors:[{id:"4951",title:"Dr.",name:"Karsten",middleName:null,surname:"Scholle",slug:"karsten-scholle",fullName:"Karsten Scholle"},{id:"133366",title:"Prof.",name:"Samir",middleName:null,surname:"Lamrini",slug:"samir-lamrini",fullName:"Samir Lamrini"},{id:"133370",title:"Prof.",name:"Philipp",middleName:null,surname:"Koopmann",slug:"philipp-koopmann",fullName:"Philipp Koopmann"},{id:"133371",title:"Mr.",name:"Peter",middleName:null,surname:"Fuhrberg",slug:"peter-fuhrberg",fullName:"Peter Fuhrberg"}]},{id:"44684",doi:"10.5772/54682",title:"A Guide to Fiber Bragg Grating Sensors",slug:"a-guide-to-fiber-bragg-grating-sensors",totalDownloads:5008,totalCrossrefCites:15,totalDimensionsCites:46,book:{slug:"current-trends-in-short-and-long-period-fiber-gratings",title:"Current Trends in Short- and Long-period Fiber Gratings",fullTitle:"Current Trends in Short- and Long-period Fiber Gratings"},signatures:"Marcelo M. Werneck, Regina C. S. B. Allil,\nBessie A. Ribeiro and Fábio V. B. de Nazaré",authors:[{id:"37623",title:"Prof.",name:"Marcelo",middleName:"M",surname:"Werneck",slug:"marcelo-werneck",fullName:"Marcelo Werneck"},{id:"61263",title:"Dr.",name:"Regina",middleName:"Célia",surname:"Allil",slug:"regina-allil",fullName:"Regina Allil"},{id:"167291",title:"MSc.",name:"Bessie",middleName:null,surname:"Ribeiro",slug:"bessie-ribeiro",fullName:"Bessie Ribeiro"},{id:"167292",title:"D.Sc.",name:"Fábio",middleName:"V. B. De",surname:"Nazaré",slug:"fabio-nazare",fullName:"Fábio Nazaré"}]},{id:"29105",doi:"10.5772/27304",title:"Synthesis of Two-Frequency Symmetrical Radiation and Its Application in Fiber Optical Structures Monitoring",slug:"synthesis-of-two-frequency-symmetrical-radiation-and-its-application-in-fiber-optical-structures-mon",totalDownloads:1727,totalCrossrefCites:25,totalDimensionsCites:35,book:{slug:"fiber-optic-sensors",title:"Fiber Optic Sensors",fullTitle:"Fiber Optic Sensors"},signatures:"Oleg Morozov, German Il’in, Gennady Morozov and Tagir Sadeev",authors:[{id:"69648",title:"Prof.",name:"Oleg",middleName:null,surname:"Morozov",slug:"oleg-morozov",fullName:"Oleg Morozov"},{id:"71962",title:"Prof.",name:"Gennady",middleName:null,surname:"Morozov",slug:"gennady-morozov",fullName:"Gennady Morozov"},{id:"71964",title:"Dr.",name:"Tagir",middleName:null,surname:"Sadeev",slug:"tagir-sadeev",fullName:"Tagir Sadeev"},{id:"120647",title:"Prof.",name:"German",middleName:null,surname:"Il'In",slug:"german-il'in",fullName:"German Il'In"}]}],mostDownloadedChaptersLast30Days:[{id:"44684",title:"A Guide to Fiber Bragg Grating Sensors",slug:"a-guide-to-fiber-bragg-grating-sensors",totalDownloads:5008,totalCrossrefCites:15,totalDimensionsCites:46,book:{slug:"current-trends-in-short-and-long-period-fiber-gratings",title:"Current Trends in Short- and Long-period Fiber Gratings",fullTitle:"Current Trends in Short- and Long-period Fiber Gratings"},signatures:"Marcelo M. Werneck, Regina C. S. B. Allil,\nBessie A. Ribeiro and Fábio V. B. de Nazaré",authors:[{id:"37623",title:"Prof.",name:"Marcelo",middleName:"M",surname:"Werneck",slug:"marcelo-werneck",fullName:"Marcelo Werneck"},{id:"61263",title:"Dr.",name:"Regina",middleName:"Célia",surname:"Allil",slug:"regina-allil",fullName:"Regina Allil"},{id:"167291",title:"MSc.",name:"Bessie",middleName:null,surname:"Ribeiro",slug:"bessie-ribeiro",fullName:"Bessie Ribeiro"},{id:"167292",title:"D.Sc.",name:"Fábio",middleName:"V. B. De",surname:"Nazaré",slug:"fabio-nazare",fullName:"Fábio Nazaré"}]},{id:"8446",title:"2 µm Laser Sources and Their Possible Applications",slug:"2-m-laser-sources-and-their-possible-applications",totalDownloads:11307,totalCrossrefCites:97,totalDimensionsCites:141,book:{slug:"frontiers-in-guided-wave-optics-and-optoelectronics",title:"Frontiers in Guided Wave Optics and Optoelectronics",fullTitle:"Frontiers in Guided Wave Optics and Optoelectronics"},signatures:"Karsten Scholle, Samir Lamrini, Philipp Koopmann and Peter Fuhrberg",authors:[{id:"4951",title:"Dr.",name:"Karsten",middleName:null,surname:"Scholle",slug:"karsten-scholle",fullName:"Karsten Scholle"},{id:"133366",title:"Prof.",name:"Samir",middleName:null,surname:"Lamrini",slug:"samir-lamrini",fullName:"Samir Lamrini"},{id:"133370",title:"Prof.",name:"Philipp",middleName:null,surname:"Koopmann",slug:"philipp-koopmann",fullName:"Philipp Koopmann"},{id:"133371",title:"Mr.",name:"Peter",middleName:null,surname:"Fuhrberg",slug:"peter-fuhrberg",fullName:"Peter Fuhrberg"}]},{id:"8431",title:"Bismuth-doped Silica Fiber Amplifier",slug:"bismuth-doped-silica-fiber-amplifier",totalDownloads:3268,totalCrossrefCites:1,totalDimensionsCites:0,book:{slug:"frontiers-in-guided-wave-optics-and-optoelectronics",title:"Frontiers in Guided Wave Optics and Optoelectronics",fullTitle:"Frontiers in Guided Wave Optics and Optoelectronics"},signatures:"Young-Seok Seo and Yasushi Fujimoto",authors:[{id:"4778",title:"Researcher",name:"Young-Seok",middleName:null,surname:"Seo",slug:"young-seok-seo",fullName:"Young-Seok Seo"},{id:"4885",title:"Dr.",name:"Yasushi",middleName:null,surname:"Fujimoto",slug:"yasushi-fujimoto",fullName:"Yasushi Fujimoto"}]},{id:"8441",title:"Magneto-Optical Devices for Optical Integrated Circuits",slug:"magneto-optical-devices-for-optical-integrated-circuits",totalDownloads:5805,totalCrossrefCites:0,totalDimensionsCites:5,book:{slug:"frontiers-in-guided-wave-optics-and-optoelectronics",title:"Frontiers in Guided Wave Optics and Optoelectronics",fullTitle:"Frontiers in Guided Wave Optics and Optoelectronics"},signatures:"Vadym Zayets and Koji Ando",authors:[{id:"4688",title:"Dr.",name:"Vadym",middleName:null,surname:"Zayets",slug:"vadym-zayets",fullName:"Vadym Zayets"},{id:"133363",title:"Prof.",name:"Koji",middleName:null,surname:"Ando",slug:"koji-ando",fullName:"Koji Ando"}]},{id:"47457",title:"Multi-User Visible Light Communications",slug:"multi-user-visible-light-communications",totalDownloads:2531,totalCrossrefCites:2,totalDimensionsCites:2,book:{slug:"advances-in-optical-communication",title:"Advances in Optical Communication",fullTitle:"Advances in Optical Communication"},signatures:"Oswaldo González, Marcos F. Guerra Medina and Inocencio R.\nMartín",authors:[{id:"143544",title:"Dr.",name:"Oswaldo",middleName:null,surname:"González",slug:"oswaldo-gonzalez",fullName:"Oswaldo González"},{id:"171546",title:"Mr.",name:"Marcos F.",middleName:null,surname:"Guerra Medina",slug:"marcos-f.-guerra-medina",fullName:"Marcos F. Guerra Medina"},{id:"172973",title:"Dr.",name:"Inocencio R.",middleName:null,surname:"Martín",slug:"inocencio-r.-martin",fullName:"Inocencio R. Martín"}]},{id:"45075",title:"Smart Technical Textiles Based on Fiber Optic Sensors",slug:"smart-technical-textiles-based-on-fiber-optic-sensors",totalDownloads:3943,totalCrossrefCites:1,totalDimensionsCites:7,book:{slug:"current-developments-in-optical-fiber-technology",title:"Current Developments in Optical Fiber Technology",fullTitle:"Current Developments in Optical Fiber Technology"},signatures:"Katerina Krebber",authors:[{id:"158312",title:"Dr.",name:"Katerina",middleName:null,surname:"Krebber",slug:"katerina-krebber",fullName:"Katerina Krebber"}]},{id:"8444",title:"Optical Deposition of Carbon Nanotubes for Fiber-based Device Fabrication",slug:"optical-deposition-of-carbon-nanotubes-for-fiber-based-device-fabrication",totalDownloads:3469,totalCrossrefCites:7,totalDimensionsCites:11,book:{slug:"frontiers-in-guided-wave-optics-and-optoelectronics",title:"Frontiers in Guided Wave Optics and Optoelectronics",fullTitle:"Frontiers in Guided Wave Optics and Optoelectronics"},signatures:"Ken Kashiwagi and Shinji Yamashita",authors:[{id:"5133",title:"Dr.",name:"Ken",middleName:null,surname:"Kashiwagi",slug:"ken-kashiwagi",fullName:"Ken Kashiwagi"},{id:"38416",title:"Mr.",name:"Shinji",middleName:null,surname:"Yamashita",slug:"shinji-yamashita",fullName:"Shinji Yamashita"}]},{id:"8425",title:"Frontiers in Guided Wave Optics and Optoelectronics",slug:"frontiers-in-guided-wave-optics-and-optoelectronics",totalDownloads:4480,totalCrossrefCites:2,totalDimensionsCites:11,book:{slug:"frontiers-in-guided-wave-optics-and-optoelectronics",title:"Frontiers in Guided Wave Optics and Optoelectronics",fullTitle:"Frontiers in Guided Wave Optics and Optoelectronics"},signatures:"Bishnu Pal",authors:[{id:"4782",title:"Prof.",name:"Bishnu",middleName:"P",surname:"Pal",slug:"bishnu-pal",fullName:"Bishnu Pal"}]},{id:"8427",title:"Nonlinear Properties of Chalcogenide Glass Fibers",slug:"nonlinear-properties-of-chalcogenide-glass-fibers",totalDownloads:4934,totalCrossrefCites:3,totalDimensionsCites:22,book:{slug:"frontiers-in-guided-wave-optics-and-optoelectronics",title:"Frontiers in Guided Wave Optics and Optoelectronics",fullTitle:"Frontiers in Guided Wave Optics and Optoelectronics"},signatures:"Jas S. Sanghera, L. Brandon Shaw, C. M. Florea, P. Pureza, V. Q. Nguyen, F. Kung, Dan Gibson and I. D. Aggarwal",authors:[{id:"5111",title:"Dr.",name:"Jasbinder",middleName:null,surname:"Sanghera",slug:"jasbinder-sanghera",fullName:"Jasbinder Sanghera"},{id:"133867",title:"Dr.",name:"Brandon",middleName:null,surname:"Shaw",slug:"brandon-shaw",fullName:"Brandon Shaw"},{id:"133868",title:"Dr.",name:"Catalin",middleName:null,surname:"Florea",slug:"catalin-florea",fullName:"Catalin Florea"},{id:"133872",title:"Prof.",name:"Gam",middleName:null,surname:"Nguyen",slug:"gam-nguyen",fullName:"Gam Nguyen"},{id:"133876",title:"Dr.",name:"Ishwar",middleName:null,surname:"Aggarwal",slug:"ishwar-aggarwal",fullName:"Ishwar Aggarwal"}]},{id:"8442",title:"Tunable Hollow Optical Waveguide and Its Applications",slug:"tunable-hollow-optical-waveguide-and-its-applications",totalDownloads:3734,totalCrossrefCites:1,totalDimensionsCites:1,book:{slug:"frontiers-in-guided-wave-optics-and-optoelectronics",title:"Frontiers in Guided Wave Optics and Optoelectronics",fullTitle:"Frontiers in Guided Wave Optics and Optoelectronics"},signatures:"Mukesh Kumar, Toru Miura, Yasuki Sakurai and Fumio Koyama",authors:[{id:"63461",title:"Dr.",name:"Mukesh",middleName:null,surname:"Kumar",slug:"mukesh-kumar",fullName:"Mukesh Kumar"},{id:"133388",title:"Prof.",name:"Toru",middleName:null,surname:"Miura",slug:"toru-miura",fullName:"Toru Miura"},{id:"133402",title:"Prof.",name:"Yasuki",middleName:null,surname:"Sakurai",slug:"yasuki-sakurai",fullName:"Yasuki Sakurai"},{id:"133404",title:"Prof.",name:"Fumio",middleName:null,surname:"Koyama",slug:"fumio-koyama",fullName:"Fumio Koyama"}]}],onlineFirstChaptersFilter:{topicSlug:"optical-engineering",limit:3,offset:0},onlineFirstChaptersCollection:[],onlineFirstChaptersTotal:0},preDownload:{success:null,errors:{}},aboutIntechopen:{},privacyPolicy:{},peerReviewing:{},howOpenAccessPublishingWithIntechopenWorks:{},sponsorshipBooks:{sponsorshipBooks:[{type:"book",id:"10176",title:"Microgrids and Local Energy Systems",subtitle:null,isOpenForSubmission:!0,hash:"c32b4a5351a88f263074b0d0ca813a9c",slug:null,bookSignature:"Prof. Nick Jenkins",coverURL:"https://cdn.intechopen.com/books/images_new/10176.jpg",editedByType:null,editors:[{id:"55219",title:"Prof.",name:"Nick",middleName:null,surname:"Jenkins",slug:"nick-jenkins",fullName:"Nick Jenkins"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}}],offset:8,limit:8,total:1},route:{name:"profile.detail",path:"/profiles/292949/yan-yu",hash:"",query:{},params:{id:"292949",slug:"yan-yu"},fullPath:"/profiles/292949/yan-yu",meta:{},from:{name:null,path:"/",hash:"",query:{},params:{},fullPath:"/",meta:{}}}},function(){var e;(e=document.currentScript||document.scripts[document.scripts.length-1]).parentNode.removeChild(e)}()