有机溶剂/缓冲液两相体系中全细胞催化拆分环氧氯丙烷

研究了有机溶剂/缓冲液两相体系中重组大肠杆菌E.coli BL21 (DE3)全细胞水解动力学拆分外消旋环氧氯丙烷制备(R)-环氧氯丙烷的过程.结果表明,最适反应条件为:最适有机溶剂异辛烷与缓冲液的体积比7:3,最适缓冲液pH 8.0,底物浓度574mmol/L,全细胞加入量0.07g湿菌体/ml溶液,温度30℃.在此条件下于1L反应器中反应45min,(R)-环氧氯丙烷的摩尔产率、光学纯度和时空产率分别达到37.5%,99.3%ee和0.286mol/(L·h).与单一水相体系相比,异辛烷/缓冲液两相体系中底物浓度和(R)-环氧氯丙烷时空产率分别提高了55.2%和98.6%.

Enzymatic resolution of epichlorohydrin catalyzed by whole cells in an organic solvent/buffer biphasic system

The biocatalytic resolution of (R,S)-epichlorohydrin to (R)-epichlorohydrin by whole cells from a recombinant Escherichia coli BL21(ED3) expressing epoxide hydrolase activity in a series of organic solvent/buffer biphasic systems was studied. Isooctane was found to be the best organic solvent. The optimum volume ratio of the organic phase to the aqueous phase, reaction temperature, pH, substrate concentration, cell concentration, and reaction time were 7:3, 30 ℃, 8.0, 574 mmol/L, 0.07 g/ml wet cells, and 45 min, respectively. Under the optimized conditions, a yield of 37.5% with 99.3% ee and an average productivity of 0.286 mol/(L·h) were obtained in a stirred reactor (1-L scale). Thus, the bioconversion was more efficient in the isooctane/buffer biphasic system than that in a monophasic aqueous system, where the substrate concentration and the average productivity of (R)-epichlorohydrin were improved by 55.2% and 98.6%, respectively.