Abstract: The effects of metal ions on astaxanthin accumulation of Phaffia rhodozyma were investigated in the paper. Three types of experimental designs were used to optimize the metal ions conditions for astaxanthin production. The first Plackett- Burman experiment design was adopted to screen key factors from eight ions. The results indicated that Zn2+, Cu2+, Mn2+ and Fe3+ contribute to synthesize astaxanthin greatly. With this first design the most important factors were determined to be used in the second experimental strategy. The method of steepest ascent was applied in order to rapidly approach the optimum. Finally, the optimal concentrations of Zn2+, Cu2+, Mn2+ and Fe3+ are 1.45μmol/L, 1.94μmol/L, 1.3μmol/L and 0.89μmol/L respectively, optimized through Box-Behnken design and RSM. In optimum conditions, the yield of astaxanthin is about 6.89 mg/L, 51% higher than the production under the initial conditions.

Key words: astaxanthin, Phaffia rhodozyma, metal ions, RSM(response surface methodology)