高校化学工程学报

对影响脂肪酶活性、稳定性和对映选择性的因素，如有机溶剂和反应温度等首先进行了优化。其次，使用悬浮于环已烷的粉末状游离脂肪酶（ＣａｎｄｉｄａｃｙｌｉｎｄｒａｃｅａｌｉｐａｓｅＯＦ３６０）作生物催化剂，成功地构建了一个高效的非水相游离酶连续搅拌釜反应器。当使用高度反应性的丙酸酐作为薄荷醇的酰基给体，进行连续的酶促对映选择性酯化反应时，醇的转化率在两周内可保持４０％以上，所生成酯的光学纯度超过９５％ｅ．ｅ。但是，当使用相应的游离丙酸（而不是酸酐）作酰基给体时，薄荷醇的转化率在连续操作开始后迅速下降，表明使用酸酐时的生产力要比使用游离酸时高。最后，对底物溶液的浓度和流速进行了进一步优化；同时对反应器系统的含水量进行了监测，并通过对酸酐料液的浓度或流速进行微调的方法，有效地将有机溶液相的水分浓度控制在一定的范围（２～４ｍｍｏｌ／Ｌ）之内，结果，ｄｌ－薄荷醇对映选择性连续酯化反应非常稳定地运行了两个月之久（转化率４７～３５％，光学纯度９５～９８％ｅ．ｅ．），酶反应器的半衰期超过２００天。

A high peformance bioreactor continuously operated for enantioselective esterification of menthol has been constructed. By using propionic anhydride as a highly reactive and non water producing acyl donor and free lipase OF 360 suspended in cyclohexane as a biocatalyst, efficient continuous enantioselective esterification of dl menthol has been stably carried out for as long as two months in a continuous stirred tank reactor(CSTR) at 30℃, with 47￣35% conversion of menthol and as high as 95￣98%e.e. optical purity of the l menthyl ester produced. However, when the corresponding propionic acid, instead of the acid anhydride, was used as an acyl donor, the conversion ratio of menthol decreased rapidly after the start of continuous operation, indicating a higher productivity in the case of the anhydride than in the case of the free acid. Water content of the reactor system in the case of the acid anhydride, as monitored by the water concentration in the organic solution phase, was easy to be controlled in a long term operation via occasional micro adjustments of the feed solution of acid anhydride and able to be kept essentially constant (2￣4 mM). Other factors affecting the activity, stability and enantioselectivity of lipase, such as the kinds of organic solvents and reaction temperature, were also optimized.