构建产苯丙酮酸还原酶的基因工程菌E. coli/ppr，优化其目的蛋白表达条件，并利用全细胞催化制备光学纯的D-苯乳酸。以Lactobacillus plantarum的基因组DNA为模板，经PCR扩增出一种编码苯丙酮酸还原酶的基因 (lpppr)，并将其在大肠杆菌BL21中进行表达。以苯丙酮酸为底物，通过单因素和正交试验优化诱导表达条件，然后对E. coli/ppr全细胞制备苯乳酸的工艺进行研究。结果表明：E. coli/ppr在IPTG终浓度为0.5 mmol/L，20℃诱导8 h时具有最高的苯丙酮酸还原酶活性。由其催化制备苯乳酸的最佳条件为：反应温度40℃，反应初始pH 6.5，葡萄糖浓度20 mmol/L。在上述条件下增加苯丙酮酸的浓度至25 mmol/L，5 h后苯乳酸的最终产率达到98.4%，产物D-苯乳酸光学纯度ee＞99.9%。

In orderto construct a genetic engineering phenylpyruvate reductase strain (E. coli/ppr), the expression conditions and bioconversion medium were optimized to increase the production of PLA with whole-cell transformation. A phenylpyruvate reductase-encoding gene, lpppr, was obtained by PCR from the genomic DNA of Lactobacillus plantarum and heterologously expressed in E. coli BL21 (DE3). Taking phenylpyruvic acid as the substrate, single factor and orthogonal experiments was used to optimized the induced expression and whole-cell catalysis conditions. Results showed that after inductionwith 0.5 mmol/L IPTG at 20 ℃ for 8 h, E. coli/ppr displayed the highest LpPPR activity. When phenylpyruvic acid was added up to 25 mmol/L, the product enantiomeric excess percent was over 99.9% and the final yield of PLA could reach 98.38% at 5 h under the obtained optimal catalytic conditionsas follows: temperature 40 ℃, initial pH 6.5 and 20 mmol/L glucose.