4 Cyanobacteria as Sources of Value-Added Products
Cyanobacteria are known to produce various fine chemicals, and there are considerable interests in the production of these chemicals from cyanobacteria on a
commercially viable scale. Two important cyanobacterial pigments, phycobiliproteins
and carotenoids, are extensively used in bio-industry and have high commercial value.
On the other hand, the major carotenoids accumulated by cyanobacteria are betacarotene, zeaxanthin, nostoxanthin, echinenone, and canthaxanthin. These pigments
are commonly used as food colorants, food additives, and supplements for human and
animal feeds. Carotenoids are well known for their antioxidant properties, and their
possible role in the prevention and control of human health and disease conditions, for
example, cancer, cardiovascular problems, cataracts, and muscular dystrophy, has been
reported (Guedes et al. 2011). Some marine cyanobacteria are valuable sources of
vitamins, and they are being used for the large-scale production of vitamins of commercial interest such as vitamins B and E. For example, Spirulina is known to be a rich
source of vitamin B12, beta-carotene, thiamine, and riboflavin. Cyanobacteria are found
to secrete a broad spectrum of enzymes that can be exploited for commercial applications. These industrially important enzymes include protease, amylase, and phosphatases. Cyanobacteria have gained a lot of attention in recent time due to their potential
applications in bioremediation and production of value-added product. They have been
considered as good source of biological products such as:
4.1 Biopolymers (Polyhydroxyalkanoate)
In conditions of excess essential nutrients, cyanobacteria usually assimilate and store
nutrients for future consumption. Various storage materials have been identified in
microorganisms, which include glycogen, sulfur, polyamino acids, polyphosphate,
and lipid. Polyhydroxyalkanoate (PHA) is a lipoidic material accumulated by
cyanobacteria in the presence of abundant carbon sources. The assimilated carbon
sources are biochemically processed into hydroxyl alkanoate monomer units, polymerized, and then stored in the form of water-insoluble inclusions (or granules) in
the cell cytoplasm. PHA is a type of biodegradable polymer that can serve as
substitute for chemical plastics and a biocompatible material that has promising
applications in biomedical or pharmaceutical field. Several cyanobacteria including
Aphanothece sp. (Capon et al. 1983), Oscillatorialimosa (Stal et al. 1990), some
species of the genus Spirulina (Vincenzini et al. 1990), and the thermophilic strain
Synechococcus sp. MA19 (Miyake et al. 1996) are natural producers of PHA.
16 Cyanobacteria: The Eco-Friendly Tool for the Treatment of Industrial Wastewaters
403
Cyanobacteria are known to produce various fine chemicals, and there are considerable interests in the production of these chemicals from cyanobacteria on a
commercially viable scale. Two important cyanobacterial pigments, phycobiliproteins
and carotenoids, are extensively used in bio-industry and have high commercial value.
On the other hand, the major carotenoids accumulated by cyanobacteria are betacarotene, zeaxanthin, nostoxanthin, echinenone, and canthaxanthin. These pigments
are commonly used as food colorants, food additives, and supplements for human and
animal feeds. Carotenoids are well known for their antioxidant properties, and their
possible role in the prevention and control of human health and disease conditions, for
example, cancer, cardiovascular problems, cataracts, and muscular dystrophy, has been
reported (Guedes et al. 2011). Some marine cyanobacteria are valuable sources of
vitamins, and they are being used for the large-scale production of vitamins of commercial interest such as vitamins B and E. For example, Spirulina is known to be a rich
source of vitamin B12, beta-carotene, thiamine, and riboflavin. Cyanobacteria are found
to secrete a broad spectrum of enzymes that can be exploited for commercial applications. These industrially important enzymes include protease, amylase, and phosphatases. Cyanobacteria have gained a lot of attention in recent time due to their potential
applications in bioremediation and production of value-added product. They have been
considered as good source of biological products such as:
4.1 Biopolymers (Polyhydroxyalkanoate)
In conditions of excess essential nutrients, cyanobacteria usually assimilate and store
nutrients for future consumption. Various storage materials have been identified in
microorganisms, which include glycogen, sulfur, polyamino acids, polyphosphate,
and lipid. Polyhydroxyalkanoate (PHA) is a lipoidic material accumulated by
cyanobacteria in the presence of abundant carbon sources. The assimilated carbon
sources are biochemically processed into hydroxyl alkanoate monomer units, polymerized, and then stored in the form of water-insoluble inclusions (or granules) in
the cell cytoplasm. PHA is a type of biodegradable polymer that can serve as
substitute for chemical plastics and a biocompatible material that has promising
applications in biomedical or pharmaceutical field. Several cyanobacteria including
Aphanothece sp. (Capon et al. 1983), Oscillatorialimosa (Stal et al. 1990), some
species of the genus Spirulina (Vincenzini et al. 1990), and the thermophilic strain
Synechococcus sp. MA19 (Miyake et al. 1996) are natural producers of PHA.
16 Cyanobacteria: The Eco-Friendly Tool for the Treatment of Industrial Wastewaters
403