Molecular characterization of freshwater microalgae and nutritional exploration to enhance their lipid yield.

Biomass and lipid yield under nutrient depleted and supplemented conditions of N and Mg in two freshwater isolates, Chlorella sp. NC-MKM and Scenedesmus acutus NC-M2 from Meghalaya were investigated for biodiesel production. Both the strains, Chlorella sp. NC-MKM and Scenedesmus acutus NC-M2 are oleaginous in nature having lipid content of 40.2 ± 1.4 and 37.3 ± 2.6% DCW, respectively. The significant increase (92.8%) in lipid content was found in N-depleted condition while an increase (46.65%) in biomass yield was observed under Mg-supplemented condition in Chlorella sp. NC-MKM. Studying the interactive effects of nutrient depletion and supplementation, combination of N-depleted and Mg-supplemented condition was selected for further investigation to check enhanced lipid yield in Chlorella sp. NC-MKM. The results showed a significant increase in biomass yield, lipid yield and lipid content (30, 66.8, and 28.66%, respectively). Under this condition, accumulation of neutral lipid was also enhanced (47.17% M2 gated cells) compared to control (21.37% M2 gated cells). Further, FAMEs revealed that the relative percentage of saturated and mono-unsaturated fatty acids increased (66.16%) in Chlorella sp. NC-MKM compared to control that improves biodiesel properties.