Spirulina tablets

Spirulina represents a biomass of cyanobacteria (blue-green algae) that can be consumed by humans and other animals. There are two species, Arthrospira platensis and Arthrospira maxima.

Arthrospira is cultivated worldwide; used as a dietary supplement as well as a whole food; and is also available in tablet, flake and powder form. It is also used as a feed supplement in the aquaculture, aquarium and poultry industries.^[1]

Etymology and ecology

Spirulina powder at 400x, unstained wet mount.

The maxima and plaetensis species were once classified in the genus Spirulina. The common name, Spirulina, refers to the dried biomass of Arthrospira platensis,^[2] which belongs to the oxygenic photosynthetic bacteria that cover the groups Cyanobacteria and Prochlorales. These photosynthetic organisms, Cyanobacteria, were first considered as algae until 1962 and for the first time, these blue green algae were added to prokaryote kingdom and proposed to call these microorganisms as Cyanobacteria ^[3] where algae is considered to be a very large and diverse group of eukaryotic organisms. This designation was accepted and published in 1974 by the Bergey’s Manual of Determinative Bacteriology.^[4] Scientifically, there is a quite distinction between Spirulina and Arthrospira genus. Stizenberger, in 1852 gave the name Arthrospira based on the septa presence, helical form and multicellular structure and Gomont in 1892, confirmed aseptate form of the Spirulina genus. Geitler in 1932, reunified both members designating them as Spirulina without considering the septum.^[5] The worldwide research on microalgae was carried out in the name of Spirulina, but the original species exploited as food with excellent health properties belongs to genus Arthrospira. This common difference between scientists and customers is difficult to change.^[4] These Arthrospira genus, constitute a helical trichomes of varying size and with various degree of coiling including tightly coiled morphology to even straight uncoiled form. The filaments are solitary and reproduce by binary fission and the cells of the trichomes vary from 2 μm to 12 μm and can sometime reach up to 16 μm. Species of the genus Arthrospira have been isolated from alkaline brackish and saline waters in tropical and subtropical regions. Among the various species included in the genus Arthrospira, A. platensis is the most widely distributed and is mainly found in Africa but also in Asia. Arthrospira maxima is believed to be found in California and Mexico.^[5] They are now agreed to be in fact Arthrospira; nevertheless, and somewhat confusingly, the older term Spirulina remains in use for historical reasons.^[1][6]

Arthrospira species are free-floating filamentous cyanobacteria characterized by cylindrical, multicellular trichomes in an open left-hand helix. They occur naturally in tropical and subtropical lakes with high pH and high concentrations of carbonate and bicarbonate.^[7] A. platensis occurs in Africa, Asia, and South America, whereas A. maxima is confined to Central America.^[1] Most cultivated spirulina is produced in open channel raceway ponds, with paddle-wheels used to agitate the water.^[7] The largest commercial producers of spirulina are located in the United States, Thailand, India, Taiwan, China, Bangladesh, Pakistan, Burma (Myanmar), Greece, and Chile.^[1]

Spirulina thrives at a pH around 8.5 and above, which will get more alkaline, and a temperature around 30 °C (86 °F). They are able to make their own food, and do not need a living energy or organic carbon source.