Thirty six strains that exhibited the catalytic activity for asymmetric reduction of ethyl pyruvate to (S)-ethyl lactate were isolated from sewage of a chemical factory in Chengdu, China and the neighboring soil. Among them, yeast strain BTY 18-6 has high catalytic activity. The asymmetric reduction of ethyl pyruvate to (S)-ethyl lactate catalyzed by BTY18-6 resting cells in an aqueous phase was examined,and the parameters influencing the bio-reduction were optimized. The results showed that, under the optimized conditions of 2.5％ glucose as co-substrate, the initial reaction pH = 6.8, the initial cell concentration at 0.175 g/ml (wet mass) cultured for 48 h, the initial ethyl pyruvate concentration at 65 mmol/L, temperature 32 ℃, and reaction time 48 h, the ethyl pyruvate conversion reached 95.5％ with enantiomeric excess of 92.1％.%从污水处理池及其附近土壤中分离到36株可将丙酮酸乙酯不对称还原成(S-乳酸乙酯的菌株,经多次复筛,最终得到一株具有较高催化活性的酵母菌BTY18-6.以BTY18-6的静息细胞为催化剂,在水相中进行丙酮酸乙酯不对称还原成(S)-乳酸乙酯的反应,并对反应条件进行了优化.结果表明,以2.5%葡萄糖为辅助底物,反应体系初始pH=6.8,发酵培养48 h的菌体湿度0.175 g/ml,丙酮酸乙酯初始浓度65 mmol/L,于32℃反应48 h的条件下,丙酮酸乙酯转化率达95.5%,产物对映体过量值(ee值)为92.1%.
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