Optimized Astaxanthin Production in Chlorella zofingiensis under Dark Condition by Response Surface Methodology

In this study, the major factors affecting both cell growth and astaxanthin production of Chlorella zofingiensis under dark were identified and optimized through statistical methods. A Plackett-Burman design was initially used to evaluate seven culture factors, of which glucose, NaNO3, and MgSO4 center dot 7H(2)O were found to be the most important in affecting C. zofingiensis. The central composite design and response surface methodology (RSM) were further used to optimize these factors. The optimized glucose, NaNO3, and MgSO4 center dot 7H(2)O concentrations for cell growth were 46.7, 1.13, and 0.125 g/L MgSO4 center dot 7H(2)O respectively, and for astaxanthin production were 35.2, 0.281, and 0.023 g/L, respectively. After the optimization, a two-stage culture strategy was employed to further maximize astaxanthin production, and the results showed that the astaxanthin yield of C. zofingiensis could reach 15.1 mg/L, which was 74% higher than that achieved in batch culture using the basal medium (i.e., 8.7 mg/L).