The Impact of Cr(III) and Cr(VI) on Lipid Accumulation in Chlorella pyrenoidosa

In this study, Chlorella pyrenoidosa was cultured with different concentrations of Cr(III) and Cr(VI), and the changes in biomass, lipid content, protein content and total sugar content of Chlorella pyrenoidosa under different culture conditions were detected. The effects of Cr(III) and Cr(VI) on the intracellular antioxidant system and related key enzymes of lipid synthesis were analyzed. The results showed that appropriate Cr(III) and Cr(VI) concentrations could make Chlorella pyrenoidosa regulate the contents of SOD, POD, ASA, CAT and GSH in cells, improve the enzyme activity of ACC and promote lipid synthesis. The aim was to investigate the mechanism of lipid synthesis by analyzing the distribution of Cr(III) and Cr(VI) in algal cells. The lipid content of Chlorella pyrenoidosa reached its highest level at 50.43 wt% and 38.00 wt% when both Cr(III) and Cr(VI) concentrations in the culture environment were 0.5 mg/L. These values were 1.37 and 1.03 times higher than the control group, respectively. The addition of appropriate Cr(III) and Cr(VI) concentrations can increase ME enzyme activity and decrease PEPC enzyme activity, shorten the biomass accumulation cycle and prolong the lipid synthesis cycle.