Sulfur Heterogeneity: A Non-Negligible Factor in Manipulating Growth and Lipid Accumulation of Scenedesmus Obliquus at a Relatively High Ratio of Carbon to Nitrogen

Algal biodiesel has been becoming a focus in the field of bioenergy worldwide. In this study, effects of heterogeneous sulfur (SO42-, SO32- and S2-) on growth and lipid accumulation of Scenedesmus obliquus cultured in wastewater with a C/N ratio of 30 were investigated, respectively. The results shown that SO42-, the optimal sulfur source, could trigger cell growth in a concentration-dependent manner. However, SO32- was superior to the others in boosting carbon uptake of cells, which was subject to NH4+-N concentration. Only SO42- could simultaneously increase lipid content and productivity of cells with a dominant component of oleic acid (C18:1n9c) occupying approximately 40% in fatty acid profile. Additionally, the genes encoding enzymes such as CDIPT, ADPRM, DPP1, pmtA and BTA1 involved in the uppermost lipid-related pathway (glycerophospholipid metabolism) were identified facing different sulfur source regardless of the concentration changes. These findings may facilitate nutrition management efforts to enhance microalgae-based biofuel production.