ptsG/mglB双基因敲除对大肠杆菌发酵混合糖产L-乳酸的影响

为增强大肠杆菌（Escherichia coli）JH16利用混合糖产L-乳酸的能力，通过Red同源重组技术敲除葡萄糖转运酶基因ptsG和半乳糖转运基因mglB，构建重组菌E. coli JH2705。结果表明，以8%混合糖（5.6%葡萄糖和2.4%木糖）为碳源，ptsG/mglB双基因缺陷重组菌E. coli JH2705同时可利用葡萄糖和木糖，大幅减小葡萄糖效应带来的不利影响，其木糖利用速率为0.60 g/（L·h），L-乳酸生产强度为1.27 g/（L·h），较出发菌株E. coli JH16分别提高50%和79.1%，E. coli JH2705的糖酸转化率高达70%，为利用木质纤维素等可再生原料高效生产L-乳酸提供技术参考。

Effect of ptsG and mglB genes knock-out on the production of L-lactic acid by Escherichia coli from mixed sugars

In order to enhance the ability of Escherichia coli JH16 to produce L-lactic acid utilizing mixed sugars, using Red homologous recombination technology, the recombinant strain JH2705 was constructed by knocking out the glucose transporter gene ptsG and galactose transporter gene mglB. The results showed that the ptsG and mglB genes deficient recombinant E. coli JH2705 could utilize glucose and xylose simultaneously with mixed sugar 8% (glucose 5.6% and xylose 2.4%) as carbon source, which greatly reduced the adverse effects of glucose. The xylose utilization rate and L-lactic acid production intensity of the recombinant E. coli JH2705 were 0.60 g/(L·h) and 1.27 g/(L·h), respectively, which were 50% and 79.1% higher than those of the original strain E. coli JH16, respectively. The sugar-acid conversion rate was 70%, which provided technical reference for the efficient production of L-lactic acid using renewable raw materials such as lignocellulose.