Influence of culture conditions on Arthrospira platensis growth and valorization of biomass as input for sustainable agriculture

Spirulina (Arthrospira platensis) is a microscopic filamentous cyanobacterium with a long history of basic and complementary alimentation. Nevertheless, a growing interest in its use in agriculture as biofertilizers and plant growth biostimulants was showed in the last years. Spirulina is commercially produced in large outdoor ponds under controlled conditions that affect both growth and biomass composition. Here, we have studied the influence of culture conditions on Spirulina growth (biomass production) and characterize the produced biomass for possible use in biopharming. The study of the effect of culture media, as well as temperature on growth and biomass composition, showed an optimal growth in temperatures at 30 and 35 °C with no difference between both tested media. The analysis of NPK content of produced biomass revealed that it contains the following: 10.9% N, 0.94% P, and 1.1 % K. In optimal growth conditions, the total biomass protein content varied from 64 to 71 %. Spirulina cells were harvested in all growth phases and analyzed for total polysaccharides (PS) in batch and continuous culture. The maximum PS production was observed during the exponential growth phase (1.5%). It was also found that the cultivation of Spirulina platensis in continuous culture increased its polysaccharide level (4.98%) compared to batch cultures.