Cyanobacteria as a healthy food source
Strains of Spirulina, Anabaena and Nostoc are consumed as human food in many countries including Chile, Mexico, Peru and Philippines. Arthrospira platensis (misidentified as S. platensis) is grown in large scale using either outdoor ponds or sophisticated bioreactors but marketed in the form of powder, flakes, tablets and capsules. It is used as a food supplement because of its richness in nutrients and digestibility. It contains more than 60% proteins and is rich in beta-carotene, thiamine and riboflavin and is considered to be one of the richest sources of vitamin B12 (see cyanobacterial active compounds). Nostoc commune is rich in fibres and proteins and can play an important physiological and nutritional role in the human diet. Aphanizomenon sp. is collected from natural blooms in the Lake Klamath (Oregon, USA) to be used as healthy food (Carmichael and Gorham 1980). Marine nitrogen-fixing cyanobacteria have also been tested to feed fishes in aquacultures. The Tilapia fish showed high growth rates when fed with marine cyanobacteria in indoor and outdoor cultures (Mitsui et al. 1983). Phormidium valderianum has been used in India to serve as a complete aquaculture feed source based on its nutritional value and nontoxic nature. In view of the cyanobacterial significance as a food source, very little research has been performed and published about this.