Optimisation of biotransformation conditions for production of 2-phenylethanol by a Saccharomyces cerevisiae CWY132 mutant.

A mutant Saccharomyces cerevisiae CWY132 was isolated, producing 1.393 g L(-1) 2-phenylethanol (2-PE) in a batch process containing 5 g L(-1) L-phenylalanine (L-Phe), which is equivalent to an increase of 38.3% compared to the initial strain. In this study, biotransformation conditions of this strain were studied. We found glucose, KH2PO4, (NH4)2SO4, and amounts of inoculum cells had significant effects on the biotransformation process; in particular, the existence of (NH(4))(2)SO(4) in the medium strongly inhibited the yield of 2-PE, while an increase in the amount of inoculum had a positive correlation with the yield of 2-PE. The optimum condition for production of 2-PE was obtained using the following uniform design: glucose 34.16 g L(-1), yeast nitrogen base 0.17 g L(-1), MgSO4 0.5 g L(-1), KH2PO4 14.89 g L(-1), (NH4)2SO4 0 g L(-1), L-Phe 5 g L(-1), and an inoculum amount of 1.6 × 10(7) cells/mL. With the optimised conditions, the yield of 2-PE was further increased to 3.52 g L(-1) (an increase of 249.5%), which corresponds to a molar conversion rate of 95.19%.