The effects of ethanol concentration gradients along with varied cultivation times on lipid and fatty acid accumulation and composition of Scenedesmus sp. were studied. The maximum increment of algal density, lipid productivity, lipid content and fatty acid content were 6.61, 11.75, 1.34 and 3.14 times higher than the control group under 12h photoperiod. Algal light deprivation inhibited ethanol positive effects on algal growth and lipid biomass. The cumulative quantity of C16:0 and C18:0 decreased correspondingly with the increase of ethanol concentrations and cultivation times. Besides, unsaturated fatty acids appeared early in algal cells and increased 57.02% in maximum. However, only 2.27% (14)C was transferred from ethanol to fatty acids. The results indicated that adding proper amount of ethanol in algal culture medium was beneficial to biodiesel feedstock production and biodiesel properties.
