Phycocyanin Production by Aphanothece microscopica Nägeli in Synthetic Medium Supplemented with Sugarcane Vinasse

This study focused on the evaluation of mixotrophic and heterotrophic production of phycocyanin by A. microscopica, analysis of kinetic parameters, the effect of freezing and thawing on phycocyanin yield, and nutrient removal during heterotrophic growth. During mixotrophic growth, maximum phycocyanin yield (1.50 mg_phycocyanin g^-1_biomass) was obtained after 12 h, while the heterotrophic cultivation yielded 1.39 mg_phycocyanin g^-1_biomass. The mixotrophic cultivation of A. microscopica showed maximum specific growth rate of 0.025 h^-1, against 0.010 h^-1 for the photoautotrophic cultivation, and 0.08 h^-1 in heterotrophic conditions. The mixotrophic cultivation had a specific rate of phycocyanin production of 9.86 mg_phycocyanin mg_biomass^-1 h^-1, while the photoautotrophic had 2.81 mg_phycocyanin mg_biomass^-1 h^-1, and the heterotrophic, 49.18 mg_phycocyanin mg_biomass^-1 h^-1. Carbon and nitrogen contents present in sugarcane vinasse were decreased in 16.69 and 15.97%, respectively, after 6 h of heterotrophic growth. Thus, it was shown that the mixotrophic production of phycocyanin by Aphanothece microscopica Nägeli in BG11 medium supplemented with vinasse is feasible.