Mixotrophic cultivation of Chlorella vulgaris in sugarcane molasses preceding nitrogen starvation: Biomass productivity, lipid content, and fatty acid analyses

In the present study, a precharacterized oleaginous microalgal species (Chlorella vulgaris) was exploited for its biomass productivity, lipid yield, and fatty acid analysis under mixotrophic and photoautotrophic conditions. For the purpose, the microalgal biomass was raised mixotrophically as well photoautotrophically. For mixotrophic cultivation, molasses was used as additional source of carbon and energy, while for photoautotrophic cultivation, atmospheric CO2 was the sole source of carbon and energy. The microalgal biomass raised thus was then harvested following 5 days of nitrogen starvation. Mixotrophic cultivation depicted remarkably higher biomass productivity (137.43 +/- 13.3 mg L-1 day(-1)) than that of photoautotrophic cultivation (91.57 +/- 7.9 mg L-1 day(-1)). About 39% (w/w) of total lipid content was obtained from the dried biomass raised mixotrophically. Lipidomic analysis of the extracted oil depicted higher concentrations of polyunsaturated fatty acids (palmitic and oleic acids). The significant availability of polyunsaturated fatty acids (60 mg g(-1) of dried algal biomass) ensured the production of high quality biofuel.