【作者】 陈勇；

【导师】 张小里；

【作者基本信息】 西北大学 ， 生物化工， 2005， 硕士

【摘要】 采用传统的平板初筛、摇瓶复筛的方法,筛选出一株具有较高选择性降解外消旋1,2-丙二醇和较高底物耐受性的菌株。通过摇瓶试验表明其底物浓度在0.292mmol/ml时,(R)-1,2-丙二醇完全分解掉,S-1,2-丙二醇留在发酵液中。 采用面包酵母催化还原丙酮醇制备(R)-1,2-丙二醇,对制备工艺进行了初步的探索。发现乙醇作为辅酶(NADH)再生的共底物是非常有效的。最优惠转化条件为:转化时间25小时,丙酮醇浓度0.154mmol/ml,pH值7.0,酵母浓度150g/L,共底物乙醇浓度0.339mmol/ml。在此基础上,用1.5L搅拌式发酵罐进行制备(R)-1,2-丙二醇的放大试验。采用分批流加底物和共底物的方法,在搅拌转速500r/min,通气量0.8L/min,温度30℃,pH6.5下,转化25小时,发酵液的(R)-1,2-丙二醇浓度为0.278mmol/ml,产率为62.3%,ee>100%。 用酵母进行了氧化拆分外消旋1,2-丙二醇的试验研究。研究了操作条件对拆分结果的影响。结果表明,氧的供给是影响拆分的重要因素,随氧供给的增加,产物丙酮醇的浓度增加,转速在250r/min时,产物浓度最大。外消旋丙二醇浓度在0.14～0.82mmol/ml间进行试验,结果表明,随底物浓度增加,产物丙酮醇的浓度增加,但是产物得率降低。底物浓度为0.14mmol/ml时,产物得率为38%。最优酵母浓度为60g/L。pH值在4～9.5间对丙酮醇浓度几乎没有影响。 以上实验结果对用生物催化合成和拆分手性1,2-丙二醇有重要的借鉴意义。更多还原

【Abstract】 A strain was screened which can selectively decompose the racemic 1,2-propanediol. The results of experiment suggested that, when the concentration of racemic 1,2-propanediol was 0.292 mmol/ml, (R)-1,2-propanediol was completely consumed, but (S)-1,2-propanediol was remained.(R)-1,2-propanediol can be obtained by reduction of acetol with Bakers Yeast. This paper groped the optimum condition of the process. We found ethanol was the very effective substance which could make co-enyzme regenerate. The optimum condition of the process was : the time for transformation was 25 hours, the concentration of acetol、 ethanol、 baker’s yeast was 0.154mmol/ml 、150g/L、 0.339mmol/ml; pH was 7.0. Based on the data, the large-scale preparation of (R)-1,2-propanediol in 1.5L fermenter was studied. Through batch-feeding acetol and ethanol, (R)-1,2-propanediol was obtained. The concentration 、 yield and ee were 0.278mmol/ml、 62.3% 、 100% respectively.This paper studied the resolution of racemic 1,2-propanediol with bakers yeast. The main content was to research the effects of the reactive condition. The results demonstrated that concentration of acetol was increasing with the increase of the oxygenic supply and racemic 1,2-propanediol. But the yield decreased with the increase of concentration of racemic 1,2-propanediol. When pH was in the range of 4 ~9.5, no effect was on the concentration of product.更多还原