Carbon sources whether types or magnitudes were fateful in terms of stimulating growth and lipids accumulation in microalgae applied for biodiesel production. The set scenario of this work was to investigate the feasibilities of glucose (G) combining with sodium acetate (SA) carbon sources in enhancing biomass and lipid accumulation in Coccomyxa subellipsoidea. The results demonstrated that C. subellipsoidea subjected to the combination feeding of G (20 g/L) and SA (12 g/L) achieved the favorable biomass (5.22 g/L) and lipid content (52.16%). The resulting lipid productivity (388.96 mg/L/day) was 1.33- to 7.60-fold more than those of sole G or SA as well as other combinations of G and SA. Even though the total fatty acids of C. subellipsoidea cells treated with the optimal combination of G and SA showed no noticeable increment in comparison with sole G or SA, the proportion of monounsaturated C18:1 (over 48.69%) and the content of C18:3 (< 12%) were commendable in high-quality algal biodiesel production. Further, such fascinating lipid accumulation in C. subellipsoidea cells treated with G combining with SA might be attributed to that G promoted glycolysis as well as SA activated glyoxylate shunt and TCA cycle to synergistically provide sufficient acetyl-CoA precursors for lipid accumulation. These findings hinted the potential of the combination of carbon sources in enhancing the overall lipid productivity to offset alga-based biodiesel production cost and would guide other alga strains cultivation.
Keywords: Biomass; Coccomyxa subellipsoidea; Glucose; Lipid productivity; Metabolites; Sodium acetate.