Evaluation of heterotrophic and mixotrophic cultivation of novel Micractinium sp. ME05 on vinasse and its scale up for biodiesel production.

Direct disposal of vinasse, a by-product of molasses fermentation plants, threatens environmental health. This study investigated the usage of vinasse as a nutrient source for the heterotrophic and mixotrophic cultivation of novel Micractinium sp. ME05. The 500-mL flask experiments resulted in higher biomass productivities under mixotrophic conditions (0.16 ± 0.01 g L-1  day1 ) than the heterotrophic conditions (0.13 ± 0.01 g L-1  day1 ). A 1.7-fold increase in biomass productivity was achieved by scaling up from 500-mL flasks (0.16 ± 0.01 g L-1  day1 ) to 2-L flasks (0.27 ± 0.019 g L-1  day1 ). The 5-L bioreactor experiments resulted in a biomass productivity of 0.32 ± 0.2 g L-1  day1 and lipid productivity of 3.4 ± 0.20 g L-1  day-1 . This study demonstrated that Micractinium sp. ME05 can be cultivated with vinasse to produce large amounts of biomass. The FAME profile of mixotrophic Micractinium sp. ME05 cells was promising for further biodiesel production. This study highlights the feasibility of industrial by- product-vinasse as the nutrient source for biomass and lipid productions using the novel Micractinium sp. ME05 cells.