Produção de ficocianina por Aphanothece microscopica Nägeli a partir de vinhaça de cana-de-açúcar

Abstract

Microalgae cultivation has a great diversity of applications. Pigments produced by microalgae are largely used in many industries, such as food, pharmaceutical and cosmetics. Phycobiliproteins are photosynthetic pigments that capture around 50% of the light needed to maintain the metabolism of cyanobacteria. A big advantage for the use of microorganisms to produce pigments is that they can assimilate low-cost energy sources, including wastewaters. In this context, the present work proposed to evaluate the production of phycocyanin by Aphanothece microscopica Nägeli, through its cultivation in vinasse, an effluent generated abundantly in Brazil. The mixotrophic cultivation of A. microscopica in BG11 medium supplemented with vinasse showed superior performance than the photoautotrophic growth, in terms of phycocyanin accumulation, with specific rate of production (μP) and maximum productivity (Prodmax) of 9.86 mg phycocyanin mg biomass/h and 0.0047 mg phycocyanin/L/h, respectively. For the heterotrophic cultivation, the highest phycocyanin production occurred after 6 hours, with μP and Prodmax of 22.59 mg phycocyanin/mg biomass/h and 0.0067 mg phycocyanin/L/h, respectively. No statistically significant difference was found for wide ranges of pH, inoculum and salinity tested. The conditions which had the highest and lowest performance relative to μPmax were selected for further experiments on a benchtop bioreactor. The condition with the highest μPmax showed maximum productivity of 49.18 mg phycocyanin/mg biomass/h, and the lowest, 33.83 mg phycocyanin/mg biomass. Phycocyanin extraction with hydrochloric acid 12 mol/L was the most efficient method, yielding up to 5,6 times more phycocyanin than sonication with glass pearls and phosphate buffer extractions . A. microscopica biomass contained 4.6% of proteins and 6.38% of lipids. Those results show that vinasse can be used as a supplement for the production of phycocyanin by A. microscopica.