Abstract: The asymmetric reduction of 2-octanone to 2-octanol by yeast in aqueous phase was investigated.The reduction product was mainly S-2- octanol.The results indicated that the conversion ratio of 2-octanoe and the enantiomeric excess values of product were both satisfactory for asymmetric reduction.It was shown also that in the catalysis of the ketone reduction the co-substrate was required to regenerate the NAD(P)H.The appropriate condition to the reaction was 30 ℃ and pH 3.0 or pH 7.0. The high concentrations of substrate and product would have some toxicity to the yeast cells and the high concentration of 2-octanol would inhibit the reduction reaction.When too much S-2-octanol existed in the medium, the S-2-octanol would be oxidized to 2-octanone by yeast, which showed that yeast could be a biocatalyst not only for reduction of 2-octanone to S-2-octanol, but also for oxidation of S-2-octanol to 2-octanone.

Key words: 酵母, 全细胞生物催化, 不对称还原, 手性化合物, S-2-辛醇

摘要： 利用活性酵母细胞催化2-辛酮的不对称还原，合成在制备光学活性物质中具有重要用途的直链手性仲醇.实验发现不对称还原的产物主要是S-2-辛醇，反应的转化率和光学选择性都比较高.考察了底物浓度、产物、辅助底物的种类及浓度，以及pH值和温度对反应的转化率和光学选择性的影响.结果表明，底物和产物对酵母的活性具有一定的毒害作用，产物2-辛醇对酮的还原反应具有抑制作用，酵母能选择性地催化S-2-辛醇氧化为相应的酮；在酵母催化还原2-辛酮的同时需要一定的辅助底物来再生辅酶NAD（P）H，利用10 g•L^-1的葡萄糖作辅助底物较好；温度30 ℃、pH值3.0或7.0为较好的反应条件.

关键词: 酵母, 全细胞生物催化, 不对称还原, 手性化合物, S-2-辛醇