Abstract:  The effects of different metal ions on cell growth, cell morphology and astaxanthin biosynthesis of Phaffia rhodozymawere studied. It indicated that Mn2+ showed clear positive effects on the β-D-glucosidase activity and cell morphology in seedculture medium. The initial ferment medium containing 0.1g/L Mn2+ could improve obviously the cell growth and astaxanthinbiosynthesis. The optimal conditions obtained by orthogonal experiment were: 0.1g/L Mn2+, 0.7g/L Mg2+ and 0.2g/L Ca2+ in theferment medium. Under the optimal conditions, the cell grows rapidly, and the astaxanthin yield reaches 2.95mg/L at 57 h, whichis 1.31 times of that under no added metal ions (at 72 h).

Key words: Phaffia rhodozyma, metal ions, astaxanthin, cell morphology, fermentation