Open access peer-reviewed chapter

Keratin Waste: The Biodegradable Polymers

Written By

Tarun Kumar Kumawat, Anima Sharma, Vishnu Sharma and Subhash Chandra

Submitted: 19 March 2018 Reviewed: 13 June 2018 Published: 19 December 2018

DOI: 10.5772/intechopen.79502

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Edited by Miroslav Blumenberg

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Keratins are everywhere, from being the major components of household dust to common contaminants of laboratory protein analysis. Keratin is the major structural fibrous protein belonging to the large family of structural proteins to form hair, wool, feathers, nails, and horns of many kinds of animals and has a high concentration of cysteine, 7–20% of the total amino acid residues, that form inter- and intramolecular disulfide bonds. Keratin wastes are considered as the environmental pollutants and produced mostly from the poultry farms, slaughterhouses, and leather industries. Keratin wastes are dumped, buried, used for landfilling, or incinerated and all these actions increase the threats of environmental hazards, pollution, negatively influence the public health, and increase greenhouse gases concentration. Nature has provided planet Earth with a variety of beneficial organisms. Soil is considered as a well-known source for the growth of keratinophilic microflora (fungi and bacteria), which have the capability to degrade the keratin waste. The keratin-degradation ability of keratinophilic microflora has been credited with the production of the microbial keratinase enzyme and biodegradation takes place (enzymatic degradation). So, the keratin wastes are the biodegradable polymers. Keratinase is the industrially significant enzyme that offers bioconversion of keratin waste, utilization as animal feed supplements, and dehairing agents in tannery industries and textile industries.


  • keratin
  • environmental pollutants
  • keratinophilic microflora
  • biodegradable polymers
  • keratinase

1. Introduction

Keratin wastes are considered as the environmental pollutants and generated mostly from the poultry farms, slaughterhouses and leather industries [1, 2]. The poultry farms, slaughterhouses, leather industries and wool industries are constantly producing a million tons of keratin waste [3]. Leather industries throw out extensive amount of waste products and considered as polluting industries with negative environmental impact [4]. The main producer of keratin waste includes the United State of America, China, India and Brazil which produces millions of tons of keratin containing protein [5, 6].

Keratin protein is the major component of the keratin waste [7] and belongs to the scleroprotein group [8]. Keratin protein is greatly resistant to the action of physical, chemical and biological agents [9]. The poultry feathers and other keratin-containing waste is dumped, land filled and incinerated throughout the world [10, 11]. These activities cause soil, water and air pollution. Discarded feather furthermore causes different human diseases including chlorosis and fowl cholera [12].

Very few microorganisms are capable to break down the keratin protein and utilize them as a source of nutrition [13]. Nature has provided earth with an assortment of beneficial organisms. Keratinophilic microflora (fungi and bacteria) is nature’s gift and the biggest group of the organisms which have the capability to degrade the keratin waste [14, 15]. Biological degradation of keratin waste is more efficient than the physical and chemical degradation, yielding more useful by-product which can be utilized in commercial applications. In this scenario, biological keratin waste degradation has received the consideration from the scientific research community in recent days [16, 17].


2. Keratin protein

Keratin is an insoluble protein that forms the major component of the outer layer of the epidermis and helps to prevent the loss of body fluids [9, 14, 18]. Keratin word initially comes into view in the literature around 1850 to describe that keratin is made up from the hard tissues [19]. Keratin is the most complex proteins of epithelial cells of vertebrates [20, 21]. Keratin protein is a tough, fibrous and the third most abundant polymer in the environment after cellulose and chitin [22, 23].

According to the sulfur content, keratin proteins are divided into (a) soft keratins – skin and callus (b) hard keratins – feather, hair, hoof and [24, 25, 26]. This protein belongs to the scleroprotein group [27, 28]. The durability of keratins is a direct consequence of their complex architecture with extremely high molecular weight [29, 30]. Keratin protein is not easily degraded by pepsin, trypsin and papain because of disulfide bonds, hydrogen bonding, hydrophobic interactions [31, 32, 33, 34].

2.1. Types of keratin

There are two types of keratin.

2.1.1. Alpha keratin (α-keratin)

Alpha keratin is found in the epithelia of all vertebrates [35]. The α-helix in alpha keratin constitutes the environmental problem due to their resistance to degradation from microbes [36, 37]. Alpha keratins in particular are remarkable for their strength, elasticity, toughness, insolubility and flexibility. Alpha (α) keratin has abundant quantities of hydrophobic amino acid, i.e. methionine, phenylalanine, valine, isoleucine and alanine [38]. According to the sulfur content, this protein is classified in hard and soft keratins [39].

2.1.2. Beta keratin (β-keratin)

Beta-keratin is structural protein and present in reptiles and birds [40]. Beta (β) keratin has high cysteine percentage and the cysteine readily forms disulfide bonds, which confer rigidity and provide enhanced resistance to degradation [41]. In a mature feather about 80–90% of β-keratin is present [42]. The molecular weight of individual keratin proteins is usually in the 10–14 kDa range [43, 44].


3. Major source of keratin protein

Keratin protein derives from living organism or from their body parts after death. The richest sources of keratin are feathers, wool, hair, hoof, scales and stratum corneum (Figure 1) [27]. Hair is the byproduct from tanneries during the haircut process [45]. Keratin protein is present in the human hair and offers flexibility, strength and durability to the hair in the form of different conformations [46, 47]. The bird’s feather is made up of over 90% of keratin protein and produced as waste by poultry-processing industries [48].

Figure 1.

Major sources of keratin protein (A) Bird’s beak; (B) animal hair; (C) human nail; (D) horn; (E) human hair; (F) hoof; (G) nail; (H) chicken feather: the hosts for these sources include human, bird and animal.

The human hair is a natural filamentous biomaterial and chemically, approximate 80% keratin protein is present in human hair [49]. The accumulation of hair causes many environmental problems and considered as waste protein [50]. Feathers protect the birds from cold, rain, sun and injury [51]. The chicken feather is composed of about 90% of keratin [52], which is a fibrous and insoluble structural protein consisting of 𝛽-helical coils joined together by disulfide linkages [53]. This structural feature enables it to resist adverse environmental conditions and degrades by proteases [16]. Therefore, feathers are considered as a biological waste and cause serious environmental problems [54].

The human nail is an important organ of the human body and primarily composed of a highly cross-linked keratin network, a scleroprotein containing large amounts of sulfur (3.8%) with several disulfide linkages. This unique structure results in a highly effective permeability barrier [55]. The beak of the birds has an external shell of hard keratin which consists almost entirely of proteins [56]. Structurally, hoof keratin contains α-helical conformation with an admixture of β-sheet and possesses high thermal stability [57].

The horn is the tough animal tissue and has inflexible configuration due to the sulfur cross-linkages [58, 59]. Fundamental components of any horns are keratin, free amino acids, peptides, lipids, remain microelements: calcium, aluminum, chromium, copper, iron, manganese, and zinc [60]. Keratin protein in the animal horn is the tough-fiber, and its treatment is very difficult [61].


4. Impact of keratin waste on environmental pollution and human health

Industry has become an essential part of modern society, and waste production is an inevitable outcome of the developmental activities. Keratin wastes are produced in huge quantities from commercial poultry processing plants, leather industries, wool industry, textile industry, and slaughterhouses (Figure 2). These wastes may pose a potential hazard to the human health or the environment (soil, air, water) [1].

Figure 2.

Major keratin waste producing industries.

4.1. Keratin waste from the poultry industry

Feathers from the chicken generated in large quantity as a waste by-product of the poultry processing plant. Worldwide, around 8.5 billion tons of poultry feather is generated annually, of which India’s contribution alone is 350 million tons. Accumulation of chicken feathers will lead to environmental contamination [12, 62, 63]. Chicken feather causes environmental pollution as well as adversely affects the people’s life living in nearby localities [64].

4.2. Keratin waste from slaughterhouses

Keratin waste is generated from the meat industry (slaughterhouses) in the form of chicken feathers, beaks, mixture of bones, organs and hard tissues in very large quantity. Keratinous wastes are degraded very slowly in nature, and considered as hazardous wastes according to EU directives [65]. The contaminated waste water generated from such industries caused the problems of acidification of soils, eutrophication and decreased species diversity. The conventional methods employed for the disposal of keratin waste are not only costly, but also very difficult. Decomposition methods like incineration are employed [20], but these procedures are environment-polluting and pose risk to the environment [66].

4.3. Keratin waste from leather industry

Leather industries are the most polluting industries globally. The leather processing is responsible for unfavorable impact on the environment [67, 68]. Keratin wastes generated from leather industries in very large amounts include both solid and liquid waste, which is mostly of animal origin [69]. A considerable amount of keratin protein waste such as hair, horns and hoofs are thrown away by leather industries [20]. Tannery industries discharge the wastes and causing serious health problems as well as pollute the air, soil, and water [70].

4.4. Keratin waste from barber shops

Barber and hair stylist shops are also the most important keratin pollution sources. Human hair is considered as environment pollutant and found as the municipal waste in the world [71]. In the city area, it often accumulates in large amounts as solid waste and chokes the drainage systems. In rural areas, hair is thrown away in nature where it slowly decomposes over several years. Open dumps of hair generate hair-dust which causes discomfort to people residing in these areas and, if inhaled in large amounts, can result in several respiratory problems [50].


5. Traditional disposal strategies of keratin waste and their disadvantages

Each year, approximately 24 billion chickens are killed across the world and huge amount of poultry feathers produces globally [72, 73], in addition to the accumulation of human hair in waste treatment facilities worldwide [51]. Keratin solid waste generated from meat, poultry processing, fish industries, wool industries considered as harmful environmental pollutants [74, 75].

Due to pathogenic microbes on the keratin waste, efficient and immediate treatment of keratin waste has become necessary [76]. The tremendous volume of keratin waste creates a serious solid waste problem in many countries [77]. The keratin waste is linked with the evolution of odors and pathogens into the soil and water [78]. Disposal of keratin waste is quite challenging [79].

Considering the huge quantity generated, there are four methods for dealing with keratin waste: incineration, landfilling, composting, and mechanical grinding (Figure 3) [20].

Figure 3.

Traditional disposal methods of chicken feather waste.

5.1. Incineration

Incineration involves combustion of keratin waste and destroying potential infectious agents [80]. Incineration plant’s temperatures are above 850°C and mostly waste is converted to CO2 and water [81]. Due to the requirement of high temperature, the operating costs are not only expensive but also difficult to maintain [6]. Incineration leads to the release of pollutants into the atmosphere, causing foul odors and contribute to harmful runoff, which negatively impacts the surrounding and downstream areas including livestock and nearby ecosystems [50].

5.2. Landfilling

The traditional method for disposal of keratin wastes is land filling [20, 79]. Historically, landfills have been the most popular methods of organized waste disposal and continue to remain in several places around the world [82]. The improper disposal of keratin wastes by landfilling contributes to environmental damage and transmission of diseases [83]. Land filling also poses problems like landfill leachate and greenhouse gases [84]. Leachate increases the nitrogen concentration in surrounding areas, leading to algal blooms and harming the ecosystem [50]. So, landfilling is the less expensive way for discarding of keratins waste, but it is not an efficient method.

5.3. Composting

Composting is the additional economical method for recycling feather waste. Ninety percent of the feather-weight consists of crude keratin protein, and also contain 15% N [85, 86]. Composting is an aerobic biological process degrading organic material of poultry, slaughterhouse wastes, manure, and litter. This process reduces the pathogens, and compost product can be used as the soil fertilizer [87, 88, 89].

5.4. Mechanical grinding

The method to dispose of keratin waste is mechanically breaking it down into useful products. In this process, the poultry feathers are hydrolyzing under heat and pressure and then grinding and drying. The dried waste ground into a powder and later processed into useful products [90]. The ground powder can be used as a nitrogen source for animal feed (mostly ruminants) or as an organic soil enhancer [91]. There are certain disadvantages of the mechanical grinding method. Extremely high temperature and grinding result in the loss of several valuable amino acids [69, 92].

Disposal of keratin waste from incineration, landfilling, composting, and mechanical grinding is restricted because of enormous production of harmful gases and poses the risk to the environment [66]. Considering the disadvantages of the above all methods, the management of keratin waste using microorganisms appears to be a viable option and it is therefore, attracting scientists for research in this field.


6. Techniques for hydrolysis of keratin waste

The management of keratin waste generated in the poultry industries, leather industries, and slaughterhouses is a major concern of many nations across the globe [93, 94]. Numbers of methods, including hydrothermal, chemical, enzymatic or biological treatments have been therefore investigated in the past few years to improve the digestibility of feathers (Figure 4) [20, 95, 96].

Figure 4.

Keratin waste hydrolysis techniques.

6.1. Hydrothermal method

The hydrothermal process usually employs high temperature (80–140°C) and high steam pressure (10–15 psi) with the addition of acids or bases for the degradation of keratin wastes [97, 98]. This method consumes the high quantity of energy and addition of acids (HCl) or bases (NaOH), which break peptide bonds of keratin [99, 100]. Hydrothermal hydrolysis of degradation also required a longer time (16 hours) for feather degradation [20].

Keratin protein is not degraded by trypsin, pepsin, and papain in its native state, because of multiple disulfide bonds [4]. Keratin waste is disposed of through thermal processing according to health regulations. The ash product that is obtained from this process is rich in macronutrients as well as micronutrients. These components have high fertilizing value [97]. The recent processes of hydrothermal treatment are costly as well as destroy amino acids and contain non-nutritive amino acids such as lanthionine and lysinoalanine [70, 101, 102].

6.2. Chemical method

The chemical hydrolysis process of keratin wastes is based on the chemicals (acid, base, catalyst). Chemical hydrolysis requires more aggressive conditions of the reaction (high temperature and pressure) and carries a greater risk to the environment [103]. The chemical hydrolysis reaction is slower and highly efficient, but causes the loss of some amino acids, e.g. tryptophan [76]. The chemical methods require more time, chemicals and energy with expensive industrial equipment for processing. The product has low nutritional value because it contains small amounts of the essential amino acids. The solubility and stability of the hydrolysates depend on the degree of protein degradation [99].

The chemical hydrolysis process increases the emission of certain gases like CO, SO2 into the environment and causes respiratory diseases, cardiovascular diseases, and cancer, among other illnesses [16]. Hence, there is an urgent need to develop biotechnological and eco-friendly alternatives for recycling of keratin waste.

6.3. Biological method

Considering the potent polluting implications and thermo-energetic cost of the above approaches for the treatment of keratin waste, microbial degradation/ biological method is an alternative, cost-effective and ecologically safe method [104, 105]. Keratinase enzymes produced by microorganisms are the possible alternative to convert keratin waste into the nutrient-rich animal feed [106, 107]. Very few microorganisms utilize keratin by enzymatic digestion as a source of nutrient substrate for growth. These microorganisms are called keratinophilic microflora.

Keratinophilic microflora represents a significant component of soil and an important group of fungi, bacteria and insects that degrade the highly stable animal proteins on earth due to the release of keratinases [14, 34, 108, 109]. Microbial keratinase is a proteolytic enzyme that posses the capability to degrade the insoluble keratin protein [110, 111, 112]. The enzymatic ability of keratin degrading microorganism to decompose keratin has long been interpreted as a key innovation [113]. Keratinase enzymes have molecular weights ranging from 18 to 240 kDa [114, 115].

Biological degradation of keratin waste is more efficient than hydrothermal and chemical degradation, resulting in more useful and toxin-free product. Thus, on employing this ability of keratinophilic microorganisms on an industrial scale, the environmental impacts of incineration and landfilling can be reduced to a great extent.

Microbial keratin degradation follows the sequence of adhesion, colonization, amplification of keratinase pursued by the breakdown and deprivation of the substrate [116]. In the process of microbial keratin degradation, microorganisms’ preliminary consumes the lipids (non-keratinous elements) and then begin to degrade keratin [117]. Keratin degradation comprises two major actions, i.e., sulfitolysis (breakdown of disulfide bonds) and proteolysis (proteolytic attack) by keratinolytic proteases (keratinases) based on the complexity nature of keratin [16, 106, 109]. Sulfitolysis is the main process of keratinolysis [118]. In this process, microorganisms discharge sulfide, which is accountable for the breakdown of keratin’s disulfide bonds [14]. In proteolysis, bacteria and fungi are able to degrade keratinous substrates proficiently due to their ability to secrete extracellular keratinase enzyme into the medium [22, 105].

Keratinophilic microbes attack keratin substrates in or on soil; therefore, biodegradation takes place [27, 119]. Several microbial strains could be valuable as they possess very significant degradation ability [94]. The keratin-degrading fungi are an environmentally important group of fungi and considered as soil saprophytes [120, 121]. The soil is rich in the keratin protein so the keratinophilic fungi easily occur and grow [122, 123]. Keratin degrading fungi colonize keratin waste and degrade them into low molecular weight [124, 125]. Most of the keratinophilic fungi belong to the families of Arthodermataceae and Onygenaceae in Ascomycetes. The keratinophilic species belong to the genera Chrysosporium, Microsporum, Trichophyton, Aspergillus, Fusarium, and Uncinocarpus [126]. These fungi are active producers of extracellular keratinase, they can be used in bioremediation of such waste and waste contaminated sites [14, 127].

A number of bacterial strains are capable of degrading keratins have been reported. Bacteria can grow faster than fungal species and therefore have potential in industrial applications. The degradation of keratin is predominantly confined by Bacillus, Microbacterium, Lysobacter, Nesternokia and Kocuria (Gram-positive bacteria) and Vibrio, and Xanthomonas and Chryseobacterium (Gram-negative bacteria) [128, 129]. The maximum feather-degrading abilities are observed mostly in the strains of Bacillus licheniformis [31, 130] and less frequently in populations of Bacillus pumilus, Bacillus cereus and Bacillus subtilis [131]. Keratin-degrading bacteria are Burkholderia, Chryseobacterium, Pseudomonas, Microbacterium sp., Vibrio, Flavobacterium, and Thermoanaerobacter [132, 133].

Studies on keratinophilic fungi started in 1952 with the discovery of hair baiting technique. This technique facilitated researchers for isolation of fungi from soil throughout the world [134]. Otcenasek [135] reported worldwide distribution of keratinophilic mycobiota in soil. Most keratin degrading fungi belong to Arthodermataceae and Onygenaceae families of the order Onygenales in Ascomycetes. The growth of fungi on temperature ranging from 15–35°C and some require a range of high temperature for optimum growth [29, 136]. Fungi grow at pH neutral to the weak acidic environment, with the highest production mycelial. Optimum pH 5.0–8.0 is suitable for conidial production and sporulation in liquid media [137, 138]. The screening of keratinolytic activity of fungi was tested through chicken feather degradation in Basal Salt Medium (BSM) [139].

Similar to isolates of fungi, lists of bacterial strains capable of degrading keratins have been reported [140]. Williams [141] isolated feather degrading Gram variable, endospore forming, motile, rod shaped bacterium and identified as Bacillus licheniformis PWD-1. This isolate demonstrated facultative growth at thermophilic temperatures with optimum at 45–50°C and pH 7.5. Deivasigamani and Alagappan [9] isolated keratinolytic Bacillus sp. from slaughterhouse and poultry farm and observed maximum keratinase activity (122.5 KU/ml) at pH 8.0. Cao [142] isolated a father degrading bacterium (Stenotrophomonas maltophilia) from decomposing poultry feathers, which showed the highest feather degrading activity at 40°C and pH 7.5–8.0. The keratin degrading microbes are widespread among the soil microbial population. These microbes have the ability to colonize and breakdown the complex keratinous waste.

The keratinophilic microorganisms effectively degrade the keratin waste and recycle them into valuable products [143]. The possible use of keratinase is in various applications such as in the poultry industries, waste bioconversion, leather industries, pharmaceutical industries, textile processing, detergent formulation, animal feed and fertilizers [144, 145, 146].


7. Conclusions

The keratinophilic microflora degrades the various keratinous waste effectively and showed the keratinolytic activity. The keratinous waste degradation by biological way is not only economical but also a possible process for better management of keratinous wastes. Keratin degrading microorganisms could be used for biotechnological application in recycling of poultry waste for environmental protection (production of nitrogenous fertilizer and animal feed) and its fermentation broth could be useful in leather industry and textile industry, etc.



We thank the Director, School of Sciences for encouragement, and the Head, Department of Biotechnology, JECRC University, Jaipur, for providing the laboratory facilities.


  1. 1. Saber WIA, El-Metwally MM, El-Hersh MS. Keratinase production and biodegradation of some keratinous wastes by Alternaria tenuissima and Aspergillus nidulans. Research Journal of Microbiology. 2010;5(1):21-35
  2. 2. Darah I, Nur-Diyana A, Nurul-Husna S, Jain K, Sheh-Hong L. Microsporum fulvum IBRL SD3: As novel isolate for chicken feathers degradation. Applied Biochemistry and Biotechnology. 2013;171(7):1900-1910
  3. 3. Mokrejs P, Krejci O, Svoboda P, Vasek V. Modeling technological conditions for breakdown of waste sheep wool. Rasayan Journal of Chemistry. 2011;4(4):728-735
  4. 4. Gousterova A, Braikova D, Goshev I, Christov P, Tishinov K, Vasileva-Tonkova E, Haertle T, Nedkov P. Degradation of keratin and collagen containing wastes by newly isolated thermoactinomycetes or by alkaline hydrolysis. Letters in Applied Microbiology. 2005;40(5):335-340
  5. 5. Sousa M, Souza O, Maciel M, Cruz R, Rego MG, Magalhaes O, Pessoa-Junior A, Porto A, Souza-Motta C. Keratinolytic potential of fungi isolated from soil preserved at the Micoteca URM. European Journal of Biotechnology and Bioscience. 2015;3(5):10-15
  6. 6. Sharma S, Gupta A. Sustainable management of keratin waste biomass: Applications and future perspectives. Brazilian Archives of Biology and Technology. 2016;59:e16150684
  7. 7. Godheja J, Shekhar SK. Biodegradation of keratin from chicken feathers by fungal species as a means of sustainable development. Journal of Bioremediation & Biodegradation. 2014;5(5):232
  8. 8. Isaac GS, Abu-Tahon MA. Dehairing capability of alkaline keratinase produced by new isolated Cochliobolus hawaiiensis AUMC 8606 grown on chicken feather. Romanian Biotechnological Letters. 2016;22(6):12147-12154
  9. 9. Deivasigamani B, Alagappan KM. Industrial application of keratinase and soluble proteins from feather keratins. Journal of Environmental Biology. 2008;29(6):933-936
  10. 10. Agrahari S, Wadhwa N. Degradation of chicken feather a poultry waste product by keratinolytic bacteria isolated from dumping site at Ghazipur poultry processing plant. International Journal of Poultry Science. 2010;9(5):482-489
  11. 11. Manirujjaman M, Amin R, Nahid AA, Alam MS. Isolation and characterization of feather degrading bacteria from poultry waste. African Journal of Bacteriology Research. 2016;8(3):14-21
  12. 12. Williams CM, Lee CG, Garlich JD, Shih JCH. Evaluation of a bacterial feather fermentation product, feather-lysate, as a feed protein. Poultry Science. 1991;70(1):85-94
  13. 13. Kunert J. Physiology of keratinophilic fungi. In: Kushwaha RKS, Guarro J, editors. Bio-logy of Dermatophytes and Other Keratinophilic Fungi. Bilbao: Revista Iberoamericana de Micologia; 2000. pp. 77-85
  14. 14. Sharma R, Rajak RC. Keratinophilic fungi: Nature’s keratin degrading machines their isolation, identification and ecological role. Resonance. 2003;8(9):28-40
  15. 15. Tridico SR, Koch S, Michaud A, Thomson G, Kirkbride KP, Bunce M. Interpreting biological degradative processes acting on mammalian hair in the living and the dead: Which ones are taphonomic? Proceedings of the Royal Society B. 2014;281:20141755
  16. 16. Gupta R, Ramnani P. Microbial keratinases and their prospective applications: An overview. Applied Microbiology and Biotechnology. 2006;70(1):21-33
  17. 17. Brandelli A. Bacterial Keratinases: Useful enzymes for bioprocessing agroindustrial waste and beyond. Food and Bioprocess Technology. 2008;1(2):105-116
  18. 18. Sharma R, Swati. Effect of keratin substrates on the growth of keratinophilic fungi. Journal of Academia and Industrial Research. 2012;1(4):170-172
  19. 19. Rouse JG, Dyke MEV. A review of keratin-based biomaterials for biomedical applications. Materials. 2010;3(2):999-1014
  20. 20. Onifade A, Al-Sane NA, Al-Musalism AA, Al-Zarban S. A review: Potentials for biotechnological applications of keratin-degrading microorganisms and their enzymes for nutritional improvement of feathers and other keratins as livestock feed resources. Bioresource Technology. 1998;66(1):1-11
  21. 21. Sapna R, Yamini V. Study of keratin degradation by some potential bacterial isolates from soil. Journal of Soil Science. 2011;1(1):01-03
  22. 22. Lange L, Huang Y, Busk PK. Microbial decomposition of keratin in nature-a new hypothesis of industrial relevance. Applied Microbiology and Biotechnology. 2016;100(5):2083-2096
  23. 23. Kumawat TK, Sharma A, Bhadauria S. Chrysosporium queenslandicum: A potent keratinophilic fungus for keratinous waste degradation. International Journal of Recycling of Organic Waste in Agriculture. 2017;6(2):143-148
  24. 24. Esawy MA. Isolation and partial characterization of extracellular keratinase from a novel mesophilic Streptomyces albus AZA. Research Journal of Agriculture and Biological Sciences. 2007;3(6):808-817
  25. 25. Tork S, Aly MM, Nawar L. Biochemical and molecular characterization of a new local keratinase producing Pseudomomanas sp., MS21. Asian Journal of Biotechnology. 2010;2(1):1-13
  26. 26. Saibabu V, Niyonzima FN, More SS. Isolation, partial purification and characterization of keratinasefrom Bacillus megaterium. International Research Journal of Biological Sciences. 2013;2(2):13-20
  27. 27. Kim JD. Purification and characterization of a keratinase from a feather-degrading fungus, Aspergillus flavus strain K-03′. Mycobiology. 2007;35(4):219-225
  28. 28. Sivakumar T, Balamurugan P, Ramasubramanian V. Characterization and applications of keratinase enzyme by Bacillus thuringiensis TS2. International Journal of Future Biotechnology. 2013;2(1):1-8
  29. 29. Sharma M, Sharma M, Rao VM. In vitro biodegradation of keratin by dermatophytes and some soil keratinophiles. African Journal of Biochemistry Research. 2011;5(1):1-6
  30. 30. Sowjanya NC, Chary CM. Degradation of few avean feathers by Microsporum gypseum. Journal of Phytology. 2012;4(4):21-23
  31. 31. Lin X, Lee CG, Casale ES, Shih JCH. Purification and characterization of a keratinase from a feather-degrading Bacillus licheniformis strain. Applied and Environmental Microbiology. 1992;58(10):3271-3275
  32. 32. Tapia DMT, Contier J. Production and partial characterization of keratinase produced by a microorganism isolated from poultry processing plant wastewater. African Journal of Biotechnology. 2008;7(3):296-300
  33. 33. Lin HH, Yin LJ. Feather meal and rice husk enhanced keratinases production by Bacillus licheniformis YJ4 and characters of produced keratinases. Journal of Marine Science and Technology. 2010;18(3):458-465
  34. 34. Sinoy TES, Bhausaheb CP, Rajendra PP. Isolation and identification of feather degradable microorganism. VSRD Technical & Non-Technical Journal. 2011;2(3):128-136
  35. 35. Vandebergh W, Bossuyt F. Radiation and functional diversification of alpha keratins during early vertebrate evolution. Molecular Biology and Evolution. 2012;29(3):995-1004
  36. 36. Kannahi M, Ancy RJ. Keratin degradation and enzyme producing ability of Aspergillus flavus and Fusarium solani from soil. Journal of Chemical and Pharmaceutical Research. 2012;4(6):3245-3248
  37. 37. Balakumar S, Mahesh N, Arunkumar M, Sivakumar R, Hemambujavalli V. Optimization of keratinase production by keratinolytic organisms under submerged fermentation. International Journal of PharmTech Research. 2013;5(3):1294-1300
  38. 38. Lehninger AB, Nelson DL, Cox MM. Principles of Biochemistry. 2nd ed. New York: Worth Publishers; 1993
  39. 39. Nickerson WJ. Biology of Pathogenic Fungi. University of Michigan: Chronica Botanica Co; 1947
  40. 40. Greenwold MJ, Sawyer RH. Molecular evolution and expression of archosaurian β-keratins: Diversification and expansion of archosaurian β-keratins and the origin of feather β-keratins. Journal of Experimental Zoology Part B: Molecular and Develop-mental Evolution. 2013;320(6):393-405
  41. 41. Strasser B, Mlitz V, Hermann M, Tschachler E, Eckhart L. Convergent evolution of cysteine-rich proteins in feathers and hair. BMC Evolutionary Biology. 2015;15:82
  42. 42. Cai C, Zheng X. Medium optimization for keratinase production in hair substrate by a new Bacillus subtilis KD-N2 using response surface methodology. Journal of Industrial Microbiology and Biotechnology. 2009;36(7):875-883
  43. 43. Woodin AM. Structure and composition of soluble feather keratin. Biochemical Journal. 1956;63(4):576-581
  44. 44. Shames RB, Knapp LW, Carver WE, Washington LD, Sawyer RH. Keratinization of the outer surface of the avian scutate scale: Interrelationship of alpha and beta keratin filaments in a cornifying tissue. Cell and Tissue Research. 1989;257(1):85-92
  45. 45. Cranston RW, Davis MH, Scroggie JG. Development of the sirolime unhairing process. Journal of the American Leather Chemists Association. 1986;81(11):347-355
  46. 46. Wagner RCC, Joekes I. Hair protein removal by sodium dodecyl sulfate. Colloids and Surfaces B: Biointerfaces. 2007;41(1):7-14
  47. 47. Velasco MVR, Dias TCD, De Freitas AZ, Vieira ND, Pinto CASD, Kaneko TM, Baby AR. Hair fiber characteristics and methods to evaluate hair physical and mechanical properties. Brazilian Journal of Pharmaceutical Sciences. 2009;45(1):153-162
  48. 48. Nagal S, Jain PC. Feather degradation by strains of Bacillus isolated from decomposing feathers. Brazilian Journal of Microbiology. 2010;41(1):196-200
  49. 49. Kaplin IJ, Schwan A, Zahn H. Effects of cosmetic treatments on the ultrastructure of hair. Cosmetics & Toiletries. 1982;97(8):22-25
  50. 50. Gupta A. Human hair “waste” and its utilization: Gaps and possibilities. Journal of Waste Management. 2014. Article ID: 498018. 17 p. DOI: 10.1155/2014/498018
  51. 51. Adetola SO, Yekini AA, Olayiwola BS. Investigation into physical and mechanical properties of few selected chicken feathers commonly found in Nigeria. IOSR Journal of Mechanical and Civil Engineering. 2014;11(3):45-50
  52. 52. Bishmi A, Thatheyus J, Ramya D. Biodegradation of poultry feathers using a novel bacterial isolate Pseudomonas aeruginosa. International Journal of Research Studies in Microbiology and Biotechnology. 2015;1(1):25-30
  53. 53. DaGioppo NM, Moreira FG, Costa AM, Alexandrino AM, De Souza CG, Peralta RM. Influence of the carbon and nitrogen sources on keratinase production by Myrothecium verrucaria in submerged and solid state cultures. Journal of Industrial Microbiology and Biotechnology. 2009;36(5):705-711
  54. 54. Chaturvedi V, Verma P. Metabolism of chicken feathers and concomitant electricity generation by Pseudomonas aeruginosa by employing microbial fuel cell (MFC). Journal of Waste Management. 2014. Article ID: 928618. 9 p. DOI: 10.1155/2014/928618
  55. 55. Gupchup GV, Zatz JL. Structural characteristics and permeability properties of the human nail: A review. Journal of the Society of Cosmetic Chemists. 1999;50(6):363-385
  56. 56. Frenkel MJ, Gillespie JM. ‘The proteins of the keratin component of bird’s beaks. Australian Journal of Biological Sciences. 1976;29(5-6):467-479
  57. 57. Kakkar P, Madhan B, Shanmugam G. Extraction and characterization of keratin from bovine hoof: A potential material for biomedical applications. Springer Plus. 2014;3(1):596
  58. 58. Mills JS, White R. The Organic Chemistry of Museum Objects. London, UK: Butterworth-Heineman; 1994
  59. 59. Mikulikova K, Romanov O, Miksik I, Eckhardt A, Pataridis S, Sedlakova P. Study of saiga horn using high-performance liquid chromatography with mass spectrometry. The Scientific World Journal. 2012. Article ID: 759604. 8 p. DOI: 10.1100/2012/759604
  60. 60. Romanov OE. The comparative analysis of horn properties and their composition. Scientific Research of Caucasus. 2005:91-95
  61. 61. Kida K, Morimura S, Noda J, Nishida Y, Imai T, Otagiri M. Enzymatic hydrolysis of the horn and hoof of cow and buffalo. Journal of Fermentation and Bioengineering. 1995;80(5):478-484
  62. 62. Mohamedin AH. Isolation identification and some cultural conditions of a protease producing thermophilic Streptomyces strain grown on chicken feather as a substrate. International Biodeterioration & Biodegradation. 1999;43(1-2):13-21
  63. 63. Huda S, Yang Y. Composites from ground chicken quill and polypropylene. Composites Science and Technology. 2008;68(3-4):790-798
  64. 64. Gerber P, Opio C, Steinfeld H. Poultry Production and the Environment – A Review. Viale delle Terme di Caracalla. Room, Italy: Animal Production and Health Division, Food and Agriculture Organization of the United Nations; 2007. p. 153
  65. 65. Deydier E, Guilet R, Sarda S, Sharrock P. Physical and chemical characterisation of crude meat and bone meal combustion residue: Waste or raw material? Journal of Hazardous Materials. 2005;121(1-3):141-148
  66. 66. Verheyen L, Wiersema D, Hulshoff-Pol L, Brandjes P, Westra P, Bos J, Jansen J. Management of Waste from Animal Product Processing. In: Livestock and Environment, Finding a Balance. Wageningen, The Netherlands: Internal Agriculture Centre; 1996
  67. 67. Kanagaraj J, Velappan KC, Chandra BNK, Sadulla S. Solid wastes generation in the leather industry and its utilization for cleaner environment – A review. Journal of Scientific and Industrial Research. 2006;65(7):541-548
  68. 68. Mushahary I, Mirunalini V. Waste management in leather industry – Environmental and health effects and suggestions to use in construction purposes. International Journal of Civil Engineering & Technology. 2017;8(4):1394-1401
  69. 69. Wang X, Parsons CM. Effect of processing systems on protein quality of feather meal and hair meals. Poultry Science. 1997;76(3):491-496
  70. 70. Syed M, Saleem T, Rehman S, Iqbal MA, Javed F, Khan MB, Sadiq K. Effects of leather industry on health and recommendations for improving the situation in Pakistan. Archives of Environmental and Occupational Health. 2010;65(3):163-172
  71. 71. Kumar S, Bhattacharyya JK, Vaidya AN, Chakrabarti T, Devotta S, Akolkar AB. Assessment of the status of municipal solid waste management in metro cities, state capitals, class I cities, and class II towns in India: An insight. Waste Management. 2009;29(2):883-895
  72. 72. Jagadeeshgouda KB, Reddy P, Ishwaraprasad K. Experimental study of behaviour of poultry feather fiber – A reinforcing material for composites. International Journal of Research in Engineering and Technology. 2014;3(2):362-371
  73. 73. Ashwathanarayana R, Shashidhara TJ, Naika R. Determination of keratinolytic potential of keratinolytic fungi on poultry feather samples isolated from selected poultry sites around Shivamogga, Karnataka, India. International Journal of Science and Research Methodology. 2015;2(2):6-13
  74. 74. Jayathilakan K, Sultana K, Radhakrishna K, Bawa AS. Utilization of byproducts and waste materials from meat, poultry and fish processing industries: A review. Journal of Food Science and Technology. 2012;49(3):278-293
  75. 75. Kumawat TK, Sharma A, Bhadauria S. Biodegradation of keratinous waste substrates by Arthroderma multifidum. Asian Journal of Applied Sciences. 2016;9(6):106-112
  76. 76. Sinkiewicz I, Sliwinska A, Staroszczyk H, Kolodziejska I. Alternative methods of preparation of soluble keratin from chicken feathers. Waste and Biomass Valorization. 2017;8(4):1043-1048
  77. 77. McGovern V. Recycling poultry feather: More bang for the cluck. Environmental Health Perspective. 2000;108(8):336-339
  78. 78. Tufaner F, Avsar Y. Effects of co-substrate on biogas production from cattle manure: A review. International journal of Environmental Science and Technology. 2016;13(9):2303-2312
  79. 79. Mehta RS, Jholapara RJ, Sawant CS. Isolation of a novel feather-degrading bacterium and optimization of its cultural conditions for enzyme production. International Journal of Pharmacy and Pharmaceutical Sciences. 2014;6(1):194-201
  80. 80. Ritter WF, Chinside AEM. Impact of dead bird disposal pits on groundwater quality on the Delmarva Peninsula. Bioresource Technology. 1995;53(2):105-111
  81. 81. Dube R, Nandan V, Dua S. Waste incineration for urban India: Valuable contribution to sustainable MSWM or inappropriate high-tech solution affecting livelihoods and public health? International Journal of Environmental Technology and Management. 2014;17(2/3/4):199-214
  82. 82. Remigios MV. An overview of the management practices at solid waste disposal sites in African cities and towns. Journal of Sustainable Development in Africa. 2010;12(7):233-239
  83. 83. Tronina P, Bubel F. Production of organic fertiliser from poultry feather wastes excluding the composting process. Polish Journal of Chemical Technology. 2008;10(2):33-36
  84. 84. Vuppu S, Sinha R, Gupta A, Goyal R. An attempt and a brief research study to produce mosquitocidal toxin using Bacillus spp. (VITRARS), isolated from different soil samples (Vellore and Chittoor), by degradation of chicken feather waste. Research Journal of Pharmaceutical, Biological and Chemical Sciences. 2012;3(4):40-48
  85. 85. Ichida JM, Krizova L, LeFevre CA, Keener HM, Elwell DL, Burtt EH. Bacterial inoculum enhances keratin degradation and biofilm formation in poultry compost. Journal of Microbiological Methods. 2001;47(2):199-208
  86. 86. Tiquia SM. Evaluation of organic matter and nutrient composition of partially decomposed and composted spent pig litter. Environmental Technology. 2003;24(1):97-107
  87. 87. Davalos JZ, Roux MV, Jimenez P. Evaluation of poultry litter as a feasible fuel. Thermochimica Acta. 2002;394(1-2):261-266
  88. 88. Thyagarajan D, Barathi M, Sakthivadivu R. Scope of poultry waste utilization. IOSR Journal of Agriculture and Veterinary Science. 2013;6(5):29-35
  89. 89. Liu J, Luo Q, Huang Q. Removal of 17 β-estradiol from poultry litter via solid state cultivation of lignolytic fungi. Journal of Cleaner Production. 2016;139:1400-1407
  90. 90. Jaouadi NZ, Rekik H, Badis A, Trabelsi S, Belhoul M, Yahiaoui AB, Aicha HB, Toumi A, Bejar S, Jaouadi B. Biochemical and molecular characterization of a serine keratinase from Brevibacillus brevis US575 with promising keratin-biodegradation and hide-dehairing activities. PLoS One. 2013;8(10):e76722
  91. 91. Hadas A, Kautsky L. Feather meal, a semi-slow-release nitrogen fertilizer for organic farming. Fertilizer Research. 1994;38(2):165-170
  92. 92. Latshaw JD, Musharaf N, Retrum R. Processing of feather meal to maximize its nutritional value for poultry. Animal Feed Science and Technology. 1994;47(3-4):179-188
  93. 93. Schmidt WF, Barone JR. New uses for chicken feathers keratin fiber. In: National Poultry Waste Management Symposium, At Memphis TN. 2004. pp. 99-101
  94. 94. Lateef A, Oloke JK, Gueguim KEB, Sobowale BO, Ajao SO, Bello BY. Keratinolytic activities of a new feather-degrading isolate of Bacillus cereus LAU 08 isolated from Nigerian soil. International Biodeterioration & Biodegradation. 2010;64(2):162-165
  95. 95. Papadopoulos MC. Effect of processing on high-protein feedstuffs: A review. Biological Waste. 1989;29(2):123-138
  96. 96. Staron P, Kowalski Z, Staron A, Banach M. Thermal treatment of waste from the meat industry in high scale rotary kiln. International journal of Environmental Science and Technology. 2017;14(6):1157-1168
  97. 97. Karthikeyan R, Balaji S, Sehgal PK. Industrial applications of keratins – A review. Journal of Scientific and Industrial Research. 2007;66(9):710-715
  98. 98. Onuoha SC, Chukwura EI. Effect of temperature and pH on bacterial degradation of chicken feather waste (CFW). International Journal of Science and Nature. 2011;2(3):538-544
  99. 99. Coward-Kelly G, Agbogbo FK, Holtzapple MT. Lime treatment of keratinous materials for the generation of highly digestible animal feed: 2. Animal hair. Bioresource Technology. 2006;97(11):1344-1352
  100. 100. Chojnacka K, Gorecka H, Michalak I, Gorecki H. A review: Valorization of keratinous material. Waste and Biomass Valorization. 2011;2(3):317-321
  101. 101. Tiwary E, Gupta R. Rapid conversion of chicken feather to feather meal using dimeric keratinase from Bacillus licheniformis ER-15. Journal of Bioprocessing & Biotechniques. 2012;2:123
  102. 102. Brandelli A, Salab L, Kalil SJ. Microbial enzymes for bioconversion of poultry waste into added-value products. Food Research International. 2015;73:3-12
  103. 103. Staron P, Banach M, Kowalski Z, Staron A. Hydrolysis of keratin materials derived from poultry industry. Proceedings of ECOpole. 2014;8(2):443-448
  104. 104. Kornillowicz-Kowalska T, Bohacz J. Biodegradation of keratin waste: Theory and practical aspects. Waste Management. 2011;31(8):1689-1701
  105. 105. Singh I, Kushwaha RKS. Keratinases and microbial degradation of keratin. Advances in Applied Science Research. 2015;6(2):74-82
  106. 106. Riffel A, Lucas FS, Heeb P, Brandelli A. Characterization of a new keratinolytic bacterium that completely degrades native feather keratin. Archives of Microbiology. 2003;179(4):258-265
  107. 107. Anbu P, Hilda A, Sur HW, Hur BK, Jayanthi S. Extracellular keratinase from Tricho-phyton sp. HA-2 isolated from feather dumping soil. International Biodeterioration & Biodegradation. 2008;62(3):287-292
  108. 108. Kansoh AL, Hossiny EN, Hameed EK. Keratinase production from feathers wastes using some local Streptomyces isolates. Australian Journal of Basic and Applied Sciences. 2009;3(2):561-571
  109. 109. Brandelli A, Daroit DJ, Riffel A. Biochemical features of microbial keratinases and their production and applications. Applied Microbiology and Biotechnology. 2010;85(6):1735-1750
  110. 110. Revathi K, Viruthagiri T. Optimization of process parameters for keratinase enzyme production using statistical experimental design. International Journal of Engineering and Innovative Technology. 2016;6(1):14-21
  111. 111. Purchase D. Microbial keratinases: Characteristics, biotechnological applications and potential. In: Gupta VK, Sharma GD, Tuohy MG, Gaur R, editors. The Handbook of Microbial Bioresources. Wallingford, UK: CAB International Publishing; 2016. pp. 634-674
  112. 112. Govarthanan M, Selvankumar T, Selvam K, Sudhakar C, Aroulmoji V, Kamala-Kannan S. Response surface methodology based optimization of keratinase production from alkali-treated feather waste and horn waste using Bacillus sp. MG-MASC-BT. Journal of Industrial and Engineering Chemistry. 2015;27:25-30
  113. 113. Sharma A, Chandra S, Sharma M. Difference in keratinase activity of dermatophytes at different environmental conditions is an attribute of adaptation to parasitism. Mycoses. 2012;55(5):410-415
  114. 114. Kublanov IV, Tsiroulnikov KB, Kaliberda EN, Rumsh LD, Haertle T, Bonch-Osmolovskaya EA. Keratinase of an anaerobic thermophilic bacterium Thermoanaerobacter sp. strain 1004-09 isolated from a hot spring in the Baikal rift zone. Microbiology. 2009;78(1):67-75
  115. 115. Tork SE, Shahein YE, El-Hakim AE, Abdel-Aty AM, Aly MM. Purification and partial characterization of serine-metallokeratinase from a newly isolated Bacillus pumilus NRC21. International Journal of Biological Macromolecules. 2016;86:189-196
  116. 116. Suzuki Y, Tsujimoto Y, Matsui H, Watanabe K. Decomposition of extremely hard-to-degrade animal proteins by thermophilic bacteria. Journal of Bioscience and Bioengineering. 2006;102(2):73-81
  117. 117. Marchisio VF. Keratinophilic fungi: Their role in nature and degradation of keratinic substrates. In: Kushwaha RKS, Guarro J, editors. Biology of Dermatophytes and Other Keratinophilic Fungi. Bilbao: Revista Iberoamericana de Micologıa; 2000. pp. 86-92
  118. 118. Blyskal B. Fungi utilizing keratinous substrates. International Biodeterioration & Biodegradation. 2009;63(6):631-653
  119. 119. Soomro IH, Kazi YF, Zardari M, Shar AH. Isolation of keratinophilic fungi from soil in Khairpur city, Sindh, Pakistan. Bangladesh Journal of Microbiology. 2007;24(1):79-80
  120. 120. Ajello L. The dermatophyte, Microsporum gypseum, as a saprophyte and parasite. Journal of Investigative Dermatology. 1953;21(3):157-171
  121. 121. Lee MJ, Park JS, Chung H, Jun JB, Bang YJ. Distribution of soil keratinophilic fungi isolated in summer beaches of the east sea in Korea. Korean Journal of Medical Mycology. 2011;16(2):44-50
  122. 122. Sharma M, Sharma M. Incidence of dermatophytes and other keratinophilic fungi in the schools and college playground soils of Jaipur, India. African Journal of Microbiology Research. 2010;4(24):2647-2654
  123. 123. Rizwana H, Abdulaziz A, Hazzani A, Siddiqui I. Prevalence of dermatophytes and other keratinophilic fungi from soils of public parks and playgrounds of Riyadh, Saudi Arabia. The Journal of Animal & Plant Sciences. 2012;22(4):948-953
  124. 124. Kumar R, Mishra R, Maurya S, Sahu B. Prevalence of keratinophilic fungi in piggery soils of Jharkhand, India. An International Quarterly Journal of Environmental Science. 2012;1:93-98
  125. 125. Malek E, Moosazadeh M, Hanafi P, Nejat ZA, Amini A, Mohammadi R, Kohsar F, Niknejad F. Isolation of keratinophilic fungi and aerobic actinomycetes from park soils in Gorgan, north of Iran. Jundishapur Journal of Microbiology. 2013;6(10):e11250
  126. 126. Tambekar DH, Mendhe SN, Gulhane SR. Incidence of dermatophytes and other keratinolytic fungi in the soil of Amravati (India). Trends in Applied Sciences Research. 2007;2(6):545-548
  127. 127. Kumawat TK, Sharma V, Seth R, Sharma A. Diversity of keratin degrading fungal flora in industrial area of Jaipur and keratinolytic potential of Trichophyton mentagrophytes and Microsporum canis. International Journal of Biotechnology and Bioengineering Research. 2013;4(4):359-364
  128. 128. Sangali S, Brandelli A. Feather keratin hydrolysis by a Vibrio sp. strain kr2. Journal of Applied Microbiology. 2000;89(5):735-743
  129. 129. Lucas FS, Broennimann O, Febbraro I, Heeb P. High diversity among feather-degrading bacteria from a dry meadow soil. Microbial Ecology. 2003;45(3):282-290
  130. 130. Ramnani P, Singh R, Gupta R. Keratinolytic potential of Bacillus licheniformis RG1 structural and biochemical mechanism of feather degradation. Canadian Journal of Microbiology. 2005;51(3):191-196
  131. 131. Sivakumar T, Shankar T, Ramasubramanian V. Purification properties of Bacillus thuringiensis TS2 keratinase enzyme. American-Eurasian Journal of Agricultural & Environmental Sciences. 2012;12(12):1553-1557
  132. 132. Riffel A, Brandelli A. Keratinolytic bacteria isolated from feather waste. Brazilian Journal of Microbiology. 2006;37(3):395-399
  133. 133. Vigneshwaran C, Shanmugam S, Kumar TS. Screening and characterization of keratinase from Bacillus licheniformis isolated from Namakkal poultry farm. Research. 2010;2(4):89-96
  134. 134. Vanbreuseghem R. Technique biologique pour l’isolement des dermatophytes du sol. Annales de la Societe Belge de Medecine Tropicale. 1952;32:173-178
  135. 135. Otcenasek M. Ecology of dermatophytes. Mycopathologia. 1978;65(1-3):67-72
  136. 136. Kumawat TK, Sharma A, Bhadauria S. Influence of liquid culture media, temperature and hydrogen ion concentration on the growth of mycelium and sporulation of Arthroderma multifidum. International Journal of Pharmaceutical Sciences Review and Research. 2016;41(2):136-141
  137. 137. Zhao H, Huang L, Xiao CL, Liu J, Wei J, Gao X. Influence of culture media and environmental factors on mycelial growth and conidial production of Diplocarpon mali. Letters in Applied Microbiology. 2010;50(6):639-644
  138. 138. Kumawat TK, Sharma A, Bhadauria S. Effect of culture media and environmental conditions on mycelium growth and sporulation of Chrysosporium queenslandicum. International Journal of ChemTech Research. 2016;9(11):271-277
  139. 139. Sharma A, Sharma M, Chandra S. Influence of temperature and relative humidity on growth and sporulation of some common dermatophytes. Indian Journal of Fundamental and Applied Life Sciences. 2012;2(4):1-6
  140. 140. Gopinath SCB, Anbu P, Lakshmipriya T, Tang TH, Chen Y, Hashim U, Ruslinda AR, Md Arshad MK. Biotechnological aspects and perspective of microbial keratinase production. BioMed Research International. 2015. Article ID: 140726. 10 p. DOI: 10.1155/2015/140726
  141. 141. Williams CM, Richter CS, MacKenzie JM, Shih JCH. Isolation, identification, and characterization of a feather-degrading bacterium. Applied and Environmental Microbiology. 1990;56(6):1509-1515
  142. 142. Cao ZJ, Zhang Q, Wei DK, Chen JW, Zhang XQ, Zhou MH. Characterization of a novel Stenotrophomonas isolate with high keratinase activity and purification of the enzyme. Journal of Industrial Microbiology and Biotechnology. 2009;36(2):181-188
  143. 143. Umedum CU, Ugorji IR, Okoye EC, Egemonye OC, Obiora SO. Keratinase activity and biodegradation properties of hyphomycetous fungi from fowl feather. International Journal of Agriculture and Biosciences. 2013;2(6):306-309
  144. 144. Adelere IA, Lateef A. Keratinases: Emerging trends in production and applications as novel multifunctional biocatalysts. Kuwait Journal of Science. 2016;43(3):118-127
  145. 145. Mini KD, Paul MK, Mathew J. Screening of fungi isolated from poultry farm soil for keratinolytic activity. Advances in Applied Science Research. 2012;3(4):2073-2077
  146. 146. Nigam PS. Microbial enzymes with special characteristics for biotechnological applications. Biomolecules. 2013;3(3):597-611

Written By

Tarun Kumar Kumawat, Anima Sharma, Vishnu Sharma and Subhash Chandra

Submitted: 19 March 2018 Reviewed: 13 June 2018 Published: 19 December 2018