Abstract: In order to study the effects of exogenous metabolic intermediates on photosynthetic efficiency and total lipid content in Scenedesmus obliquus XJ002, we added metabolic intermediates (citric acid and malic acid)to study biomass, photosynthetic pigments, chlorophyll fluorescence characteristics and lipid content of XJ002. The results showed that the addition of high concentrations of metabolic intermediates resulted in a significant decrease in biomass, chlorophyll a, chlorophyll b and carotenoid content. The high concentration treatments could damage the oxygen evolving complex at the donor side of reaction center of photosystem II, and inhibited electron transfer activity of receptor side of reaction center of photosystem II. The addition of intermediate metabolites resulted in a significant increase in the total lipid content of XJ002. When the concentration of citric acid and malic acid was 0.15 g/L, the total lipid content was 1.85 and 1.34 folds higher than the control group. The addition of high concentration of metabolic intermediates results in a significant increase in total lipid content in the cell of XJ002. Compared with malic acid, citric acid has the better effect.

Key words: citric acid, malic acid, Scendesmus obliquus, chlorophyll fluorescence, total lipid