响应面法优化重组大肠杆菌全细胞合成D-苯基乳酸

研究利用重组大肠杆菌Escherichia coli BL21（DE3）/pET-28a-ldhD全细胞生物转化苯丙酮酸（phenylpyruvic acid，PPA）合成D-苯基乳酸（D-phenyllactic acid，D-PLA）的条件。通过Plackett-Burman试验设计，从影响细胞转化的6 种因素中筛选得出转化温度、底物浓度和磷酸钠缓冲液pH值对底物PPA摩尔转化率有显著影响；采用Box-Behnken试验设计和响应面优化，对该重组菌全细胞转化合成D-PLA的条件进行了优化。最佳分批转化条件：转化温度为38 ℃、底物浓度为42 mmol/L、磷酸钠缓冲液pH 7.0、菌体质量浓度20 g/L、葡萄糖质量浓度20 g/L。在该条件下反应0.5 h，底物摩尔转化率为65.32%。根据此最佳转化条件，经4 h的间歇补加底物转化获得D-PLA最终浓度为119 mmol/L（19.75 g/L），生产率为4.94 g/（L·h）。

Optimization of D-Phenyllactic Acid Production by Whole Cells of Recombinant Escherichia coli Using Response Surface Methodology

The bioconversion conditions for the production of D-3-phenyllactic acid from phenylpyruvic acid (PPA) using
whole cells of Escherichia coli BL21(DE3)/pET-28a-ldhD were studied. Using Plackett-Burman design, buffer pH, substrate
concentration and temperature were selected as the factors with significant influence on substrate conversion efficiency out
of 6 factors. Subsequently, the optimization of the three factors was carried out using Box-Behnken design and response
surface analysis. Results indicated that the optimal bioconversion conditions that provided the maximum molar conversion
efficiency of PPA (65.32%) during 30 min were buffer pH 7.0, substrate concentration 42 mmol/L, and temperature 38 ℃,
cell concentration 20 g/L and glucose concentration 20 g/L. Under these conditions, 119 mmol/L (19.75 g/L) of D-PLA with
a productivity of 4.94 g/(L·h) was obtained after 4 h transformation with intermittent PPA feeding.