Production of astaxanthin by a mutant strain of Phaffia rhodozyma and optimization of culture conditions using response surface methodology

To improve astaxanthin production in yeast, Phaffia rhodozyma 2.1557 was subjected to mutagenesis. A genetically stable mutant, YZUXHONG686, was isolated through the screening of combined carotenes biosynthesis inhibitors, and demonstrated a high yield of astaxanthin. Sequential methodology was employed to optimize the astaxanthin production of mutant stain YZUXHONG686 and minimize the cost of production. A screening test was first conducted using a Plackett-Burman design and variables with statistically significant effects on astaxanthin biosynthesis were identified. These significant factors were optimized by central composite designed experiments and response surface methodology. Finally, an initial value of pH 5.09 as well as sucrose and dried corn steep liquor powder concentrations of 49.32 g/L and 4.77 g/L, respectively, were found to give an optimal final carotenes concentration of 53.68 +/- 1.72 mg/L. The astaxanthin yield was 2.56 +/- 0.68 mg/g dry biomass under the optimized conditions.