β-羟基异丁酸是一种重要的化工医药产品,主要用于合成降压药卡托普利和其它的光学活性物质。试验利用氧化葡萄糖酸杆菌不对称氧化2-甲基-1,3-丙二醇合成了光学纯的(R)-β-羟基异丁酸,研究表明:在28℃和pH值5.5、底物浓度5 g/L、湿细胞浓度20 g/L的情况下,经过10 h的反应,(R)-β-羟基异丁酸的浓度达到20.5 g/L,转化率和光学纯度分别达到88.6%和95.3%。在培养基中添加一定量(0.1%)的1,2-丙二醇和乙二醇对菌体生长、立体选择性和催化活性都有一定的促进作用。通过流加2-甲基-1,3-丙二醇使其在反应体系中的浓度维持在5 g/L以下,以消除过高的底物浓度对细胞活性的抑制,在3.7 L反应器中经过24 h的反应,(R)-β-羟基异丁酸的浓度提高到50.2 g/L,摩尔转化率和光学纯度分别达到90.5%和93.2%。

β-Hydroxyisobutyric acid(β-HIBA) is an important chemical commodity,which is used in the syn-thesis of Captopril and other optically active compounds.Microbial asymmetric oxidation of 2-methyl-1,3-propandiol using resting cells of Gluconobacter oxydans DSM 2003 was investigated for the synthesis of R-enantiomers of β-HIBA.The results indicated that the concentration of R-β-HIBA reached 20.5 g/L with a molar conversion rate of 88.6% and the optical purity of 95.3% at 10 h under the following conditions: temperature 28℃,pH5.5,substrate concen-tration 5 g/L and cell concentration 20 g/L.Biamass,stereo-selectivity and cell activity of Gluconobacter oxydans DSM 2003 were improved when 0.1% 1,2-propanediol or ethylene glycol was added in the culture medium.Under the optimized reaction conditions in 3.7 L bioreactor,the concentration of R-β-HIBA reached 50.2 g/L with a molar conversion rate of 90.5% and the optical purity of 93.2% at 24 h in a 2-l batch reaction.It was proved efficient and a potential process for the oxidation of 2-methyl-1,3-propanediol to(R)-β-HIBA.