Abstract:

Fractional factorial design was used to evaluate effects of related factors on astaxanthin production by Phaffia rhodozyma fermentation. Based on this, central composite design combined with response surface methodology was employed for optimizing the most important affecting factors of astaxanthin production. Results showed that the factors including initial pH, yeast extract amount, concentrations of glucose and fructose exhibited the most important effects on astaxanthin yield. The optimal fermentation medium composition for high astaxanthin yield consisted of 5.6 g/L yeast, 24 g/L glucose and 21 g/L fructose with an initial pH value of 8.5. This optimization resulted in an increase of astaxanthin yield from 10900 to 5890 μg/L. Moreover, enlarged fermentation in a 7.5 L fermentor gave an astaxanthin yield as high as 18300 μg/L with an enhancement of 68% when compared with shake flask fermentation.

Key words: Phaffia rhodozyma, astaxanthin, factorial design, response surface methodology (RSM)