Although Spirulina species are widely exploited for the commercial production of phycobiliproteins, high light intensities and elevated temperatures negatively affect both biomass productivity and phycocyanin (PC) content. Moreover, they require mechanical cell disruption methods, thereby increasing overall extraction costs. Therefore, there is a growing need to explore alternative cyanobacterial strains with improved stress tolerance and more efficient pigment recovery. In the present study, two indigenous salt-tolerant cyanobacterial strains, Pseudanabaena limnetica and Phormidium persicinum, isolated from the salt pans of the Mumbai suburban region, were evaluated for their potential to produce phycobiliproteins under tropical outdoor conditions. The PC extraction protocol was standardised for both isolates by optimising buffer type, molarity, pH and freeze-thaw cycles. The effect of outdoor culturing on biomass and phycobiliprotein yield was also assessed. For P. limnetica, two freeze-thaw cycles using potassium phosphate buffer (0.1 M, pH 6.2) resulted in significantly higher PC extraction efficiency, as confirmed by one-way ANOVA followed by Tukeys’ post-hoc test. For P. persicinum cultured indoors, one freeze-thaw cycle with sodium phosphate buffer (0.1 M, pH 6.2) yielded the highest pigment recovery, producing 0.93 mg mL-1 of PC and 1.03 mg mL-¹ of phycoerythrin (PE). Under outdoor culture conditions, potassium phosphate buffer (pH 6.2) was also found to be optimal for extraction from P. persicinum.
Aasiya et al. (2026) studied this question.