Arthrospira (Spirulina)

Summary: The successful commercial exploitation of Arthrospira because of its high nutritional value, chemical composition and safety of the biomass has made it one of the most important industrially cultivated microalgae. Knowledge of its biology and physiology, which is essential for understanding the growth requirements of this alkaliphilic organism, has been used in developing suitable technologies for mass cultivation. The relationships between environmental and cultural factors, which govern productivity in outdoor cultures, are discussed in connection with growth yield and efficiency. The response of Arthrospira and its modification under stress are described, together with the strategy of osmotic adjustment and the mechanism of internal pH regulation to alkalinity. The metabolic plasticity of the response to disparate environmental stimuli is demonstrated in the natural environment, but is also well-expressed in the maintenance of high productive monoculture in intensive outdoor cultivation systems. While the confused taxonomy of Arthrospira and its relationship with Spirulina has been resolved by study of the ultrastructural feature of trichomes and 16S rRNA sequence analysis, the problem of species definition is still ongoing. However, molecular methods such as total DNA restriction profile analyses of a wide range of strains are helping to resolve this.