The major microalgal species, products, and application.
Microalgae are a large diverse group of microorganisms comprising photoautotrophic protists and prokaryotic cyanobacteria—also called as blue-green algae. These microalgae form the source of the food chain for more than 70% of the world’s biomass. It contains higher nutritional values, with rapid growth characteristics. Microalgae are autotrophic organisms and extensively desired for use in nutraceuticals and as supplement in diet. Many microalgal species are documented for health benefits, by strengthening immune system and by increasing the nutritional constitution of body. In this chapter the major economically important species like Spirulina, Chlorella, Haematococcus, and Aphanizomenon are described with reference to its importance as nutraceuticals and food.
- food supplements
Microalgae are a large diverse group of microorganisms comprising photoautotrophic protists and prokaryotic cyanobacteria—also called as blue-green algae. These microalgae form the source of the food chain for more than 70% of the world’s biomass . Microalgae are single-celled, microscopic photosynthetic organisms, found in freshwater and marine environment. They produce compounds such as protein, carbohydrates, and lipids. Mostly, microalgae are photosynthetic microorganisms; it does not contain cell organelles unlike land plants. They use the carbon from air for energy production.
Microalgae can be cultivated photosynthetically using CO2, solar energy, and water. It can be cultivated in shallow lagoons, marginal ponds, raceway ponds, or artificial tanks. The use of plastic tubes/reactors in pond system can achieve up to seven times the production efficiency compared to open culture system .
There are more than 300,000 species of microalgae, out of which around 30,000 are documented. They live in complex natural habitats and can adapt rapidly in extreme conditions (in variation of extreme weather conditions). This ability makes them capable to produce secondary metabolites, with novel structure and biologically active functions.
Microalgae produce some useful bio-products including β-carotene, astaxanthin, docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), bioactive and functional pigments, natural dyes, polysaccharides, antioxidants, and algal extracts. The first commercial cultivation of
Algae are classified into many major groups, based on pigment composition, storage compound, and diversity in features of its ultrastructure. However, advance molecular biology-based techniques are nowadays used to check the relation between taxonomic groups and families of the specific class.
The global market value of microalgae is estimated to be around US$ 6.5 billion, out of which about US$ 2.5 billion is generated by the health food sector, US$ 1.5 billion by the production of DHA, and US$ 700 million by aquaculture. The annual production of microalgae is approximately 7.5 million tons.
2. Microalgal diversity
The diversity of microalgae is vast and represents an intact resource. The scientific literature indicates the existence of 200,000 to several million species of microalgae when compared to about 250,000 species of higher plants .
Green microalgae usually grow in freshwater and seawater, whereas several other species of microalgae grow in extremely saline environments, such as the Great Salt Lake in UT, USA, and the Dead Sea in Israel. Within these aqueous habitats, some algae grow inside the deeper waters, others populate the subsurface water column, and a few grow at the limits of the photic zone, 200–300 m below the water surface [5, 6, 7, 8]. The microalgae are small in size (mostly 5–50 μm) and characterized by a simple morphology, usually unicellular. Accordingly, most of the species are not observed as an individual cell/specimen but become noticeable only when it generates large colony, specially in the form of green, black, red, or brown patches on the water surface. Coastlines between 45 and 30°N are suitable regions for algal farming, in particular in those territories at the south of the Mediterranean that experience warmer climates and whose temperature does not go too much below 15°C throughout the year . This type of warmer climate of the Mediterranean region can facilitate the algal growth in the open or closed pond system.
The environmental parameters favorable for mass scale culture are explored by many counties. For example, Israel and few Mediterranean countries have explored specific parameters for each economically important alga and cultivating it by maintaining them artificially for mass scale production. Few advance countries have started culturing several microalgal strains of biofuel production, while countries like Libya, Cyprus, and Turkey also have plenty of marginal lands to harvest algae. For these countries a limited water resource is not a constraint as they are using recycled brackish or saline water. With the high temperatures in the Mediterranean region, the open or closed pond system would probably be the most efficient and suitable to grow algae.
Terrestrial microalgae belong primarily to three diverse evolutionary pedigrees: the blue-green algae (Cyanobacteria), the green algae (Chlorophyta and Streptophyta), and the diatoms (Bacillariophyceae, Ochrophyta) . However, the species of green and blue-green algal group are the majorly studied group, taxonomically as well as with economical perspective. Nevertheless, the understanding of the patterns of geographical distribution in terrestrial algae is inadequate, mainly due to poor understanding of the diversity of these organisms .
3. Microalgae: uses as nutraceuticals and food
Microalgae have a wide range of industrial applications, in food industries, wastewater purification, and pharmaceutical formulations . Microalgae can also be used for high-value food, health food for human, polysaccharides, food and fodder additives, cosmetics, antioxidants, anti-inflammatory objects, dyes and feed for aquaculture, and preparation of biofilms [3, 12, 13].
The most widely used microalgae include Cyanophyceae (blue-green algae), Chlorophyceae (green algae), Bacillariophyceae (including diatoms), and Chrysophyceae (including golden algae). Table 1 highlights some major microalgal species, products, and their application.
|Phycocyanin, biomass||Health food, cosmetics|
|Protein, vitamin B12||Antioxidant capsule, immune system|
|Protein, essential fatty acids, β-carotene||Health food, food supplement|
|Biomass, carbohydrate extract||Animal nutrition, health drinks, food supplement|
|Carotenoids, β-carotene||Health food, food supplement, feeds|
|Carotenoids, astaxanthin||Health food, food supplement, feeds|
|Fatty acids, EPA||Pharmaceuticals, cosmetics, anti-inflammatory|
|Fatty acids||Animal nutrition|
|Lipids, fatty acids||Nutrition, fuel production|
|Immune modulators||Pharmaceuticals, nutrition|
|DHA and EPA||Food, beverage, and food supplement|
|DHA||Brain development, infant health and nutrition|
|Biomass||Food for larval and juvenile marine fish|
Since the last 20 years, biotechnological and nutraceutical application of microalgae has focused specifically on four major microalgae: (a)
Spirulina is a prokaryotic cyanobacterium that has been commercially produced for over 30 years for uses including fish food, vitamin supplements, food dyes, aquaculture, pharmaceuticals, and nutraceuticals [15, 16].
|Amino acids (g kg−1)|
Photoautotrophic culture of
|Composition content (% of DW)||Green stage||Red stage|
|Lipids (% of total)||20–25||32–37|
|Carotenoids (% of total)||0.5||2–5|
|Astaxanthin (including esters)||n.d||81.2|
|Vitamin B1 (thiamin)||0.001||0.0009||0.00047||0.0023||0.004|
|Vitamin B2 (riboflavin)||0.0045||0.0009||0.0017||0.005||0.0006|
|Vitamin B3 (niacin)||0.0149||0.001||0.0066||0.025||0.025|
|Vitamin B5 (pantothenic acid)||0.0013||0.0005||0.0014||0.0019||0.0008|
|Vitamin B6 (pyridoxine)||0.00096||0.0004||0.00036||0.0025||0.0013|
|Vitamin B9 (folic acid)||0.000027||0.00004||0.00029||0.0006||0.0001|
|Vitamin B12 (cobalamine)||0.00016||0.000004||0.00012||0.000008||0.0006|
As the human population continues to increase, the demand for nutritive food and health products increases concomitantly. The sources of nutritive biomass that can meet this demand are pursued rampantly. Their wide diversity, fast growth, and diverse uses make them easily accepted for commercial culture. Microalgae require much fewer resources as compared to other crops. The role of algae in human health and nutrition will continually increase with additional research in the areas of health benefits and culturing. The usage of currently produced algae primarily includes food, food additives, aquaculture, colorants, cosmetics, pharmaceuticals, and nutraceuticals. Very few algal species are being cultivated for human use. There are likely more species of algae that have not been identified than ones that have and those still numbers in the thousands. Therefore, the potential for algal use in the realms of food consumption, health supplements, energy production, and many more is likely to intensify in the years to come.