Effects of trophic elements and pH on growth rate and lipid productivity of Chlorella zofingiensis cells

We investigated the biomass productivity and lipid content in Chlorella zofingiensis under different trophic modes (autotrophic, mixotrophic and heterotrophic), with different nitrogen,concentration of phosphorus and pH. The results indicate that the biomass productivity and lipid content of C. zofingiensis under mixotrophic cultivation are higher than that of under autotrophic and heterotrophic cultivation. The lipid productivity of C. zofingiensis is 3.14 gL-1 under mixotrophic cultivation with sucrose, which is 4.6 and 5.0 folds of those obtained under autophototrophic and heterotrophic conditions. The maximum lipid productivity is 0.79 gL-1 with CON2H4 as nitrogen source. The lipid productivity of C. zofingiensis increases with K2HPO4 concentration at 0~80 mgL and optimum concentration of phosphorus is 7.0~14.0 mgL-1. In addition, different pH values have great influence on the growth of C. zofingiensis cells, which live in pH from 4.5 to 9.5, while die soon when pH exceeds this range.