Cultivations of Arthrospira maxima (Spirulina) using ammonium sulfate and sodium nitrate as an alternative nitrogen sources

Arthrospira (Spirulina) has been considered as an attractive microalgae in all aspects of human life including medicine, cosmetics, and food. Nitrogen source is an important cost-saving factor in large-scale cultivation. In the present study, the cultivation of S. maxima was studied by replacing the basic-nitrogen source of Zarrouk’s medium (2.5 gL-1) with concentration ranges of 0-10 gL-1 for sodium nitrate and 0-5 gL-1 for ammonium sulfate in terms of biomass and phycobiliproteins production. Biomass and phycobiliprotein growth of different nitrogen sources have shown different effects on growth. The changes in the amount of cell dry weight as a function of sodium nitrate did not show significant changes relating to its concentration. In case of ammonium sulfate, the cell dry weight of S. maxima without nitrogen source was 0.835 gL-1 during five days of cultivation. Moreover, phycocyanin and allophycocyanin contents were 0.053 and 0.072 mgL-1, respectively, while phycobiliproteins content and cell dry weight were decreased by increasing further concentration. There was a significant difference among the culture mediums containing ammonium sulfate and without nitrogen source in terms of concentration of biomass and phycobiliprotein. The highest and lowest results for cell dry weight and phycobiliprotein production were obtained from the treatment with nitrogen starvation and 5 gL-1 ammonium sulfate, respectively. Finally, nitrogen starvation was proved as a feasible way to grow and could be good candidate for biomass growth and phycobiliprotein.