Effects of light intensity and nitrogen limitation on cell growth and cell composition of Chlorella sorokiniana

The effects of light intensity and nitrogen limitation on cell growth and cell composition of Chlorella sorokiniana was investigated in this study.The results showed that a high light intensity could significantly improve biomass productivity and carbohydrate content of Chlorella sorokiniana,but caused a slight decrease in lipid content and protein content. The highest biomass productivity( 935.6 mg · L^-1·d^-1),protein productivity( 509.8 mg·L^-1·d^-1) and carbohydrate productivity( 256.0 mg·L^-1·d^-1) were achieved at a light intensity of750 μmol·m^-2·s^-1,while the highest lipid productivity( 105.0 mg·L^-1·d^-1) was obtained at a light intensity of450 μmol·m^-2·s^-1. Moreover,nitrogen deprivation was employed to trigger the accumulation of lipid and carbohydrate.It was found that under nitrogen deprivation for 2 days and 4 days,the carbohydrate productivity and lipid productivity of Chlorella sorokiniana could be further increase to 471.1 mg·L^-1·d^-1and 150.6 mg·L^-1·d^-1,respectively.