Optimization of growth, lipid and chlorophyll contents in Chlorella vulgaris under different conditions of nitrate, phosphate and photoperiod by central composite design (CCD)

The effects of nitrate (750-2250 mg/L), phosphate (20-60 mg/L) and photoperiod (8-24 h) on the growth, chlorophyll content and lipid yield of Chlorella vulgaris were studied using central composite design (CCD) method. The second-order quadratic model was used to predict the effects of input variables on the output responses and the results were verified by F test, ANOVA and regression analyses. Results showed that maximum growth (255.88 ×106) as well as highest chlorophyll content (15.34%) were observed at 16 h of light, 1500 mg/L of nitrate and 40 mg/L of phosphate concentration. Also, condition of 24 h of light, 750 mg/L nitrate and 20 mg/L phosphate concentrations resulted in maximum percent of lipid content (17.74%). The optimization of culture condition for simultaneous achievement of highest levels of growth, chlorophyll and lipid content were investigated.