树脂吸附对红酵母催化苯乙酮不对称还原反应的促进作用

以红酵母静息细胞催化苯乙酮不对称还原合成(S)-α-苯乙醇为模型反应, 研究了在反应体系中加入吸附树脂对反应的影响. 结果表明, 水相中较高浓度(＞50 mmol/L)的苯乙酮对红酵母细胞具有显著毒性; 加入适量的吸附树脂可以降低水相中苯乙酮的浓度从而减小对细胞的毒害作用. 考察了3种不同极性的吸附树脂(HZ-801, HZ-806和HZ-816)对底物和产物的吸附能力, 发现在3种树脂中疏水性最强的HZ-816树脂对反应底物和产物具有相对较高的吸附能力. 进一步研究结果表明, 当底物浓度为100 mmol/L, 细胞湿重为500 g/L时, 与不加树脂的对照实验相比, 加入100 g/L HZ-816树脂后, 使得48 h的反应转化率从54%提高到91%, 与此同时细胞的死亡率从99%下降为10%. 含有产物的树脂经乙醇解吸后即可循环使用.

Promoting Effect of Resin Adsorption on Asymmetric Reduction of Acetophenone Catalyzed by Rhodotorula sp. Cells

Asymmetric reduction of acetophenone to (S)-α-phenylethyl alcohol by Rhodotorula sp. cells was chosen as the model reaction to study the effect of introducing adsorption resins into the reaction system. It was shown that the substrate at a high concentration (＞50 mmol/L) in aqueous phase did have obvious toxicity to yeast cells, which could be greatly lowered by introducing an appropriate amount of resin into the reaction system to keep the substrate and product at low concentrations in aqueous phase. Three kinds of resins (HZ-801, HZ-806 and HZ-816) with different degrees of hydrophobicity were tested for their capability of adsorbing the substrate and product. As a result, HZ-816 resin with a higher hydrophobicity than the others showed the highest ability of adsorbing acetophenone and α-phenylethanol. And an increased conversion of the substrate from 54% to 91% and a decreased death rate of cells from 99% to 10% were observed after reaction for 48 h when HZ-816 resin of 100 g/L was added to the reaction system with 100 mmol/L of substrate concentration and 500 g/L (wet weight) of the yeast cells. After the reaction, the resin could be reused after the desorption of product by ethanol.