产D-乳酸重组大肠杆菌ptsG基因的敲除及其混合糖同步发酵

The Knockout of Gene ptsG of Recombinant Escherichia coli Producing D-lactic Acid and the Simultaneous Fermentation of Mixed Sugars

为构建能够同时高效利用五碳糖和六碳糖发酵产D-乳酸的重组大肠杆菌工程菌,以能高效利用五碳糖发酵产D-乳酸的大肠杆菌工程菌E.coli JH13为出发菌株,通过Red同源重组技术敲除葡萄糖跨膜转运基因pts G。实验结果表明,pts G缺陷菌株E.coli JH15在10%混合糖(5%葡萄糖和5%木糖)培养基中发酵,可同时利用五碳糖和六碳糖以完成发酵;而对照菌葡萄糖消耗完才利用木糖,发酵结束还有18 g/L木糖残留;JH15乳酸产量为83.04 g/L,相比于对照菌株提高了25.86%;在稻草秸秆水解液中发酵,JH15同时利用葡萄糖、木糖和L-阿拉伯糖,乳酸产量为25.15 g/L,转化率为86.42%。JH15作为能利用混合糖同步发酵产D-乳酸的大肠杆菌工程菌,它的成功构建为利用廉价的木质纤维素水解物为原料发酵生产D-乳酸提供参考依据。

In order to construct a recombinant engineering Escherichia coli strain that yields D-lactic acid in the simultaneous efficient fermentation of pentose and hexose, having an engineering E. coli JH13 that efficiently ferment the pentose to produce D-lactic acid as an original strain, a glucose transmembrane transporter gene pts G was knocked out by the technique of Red homologous recombination. The fermentative results showed that in the 10% mixed sugars（5% glucose and 5% xylose）, the pts G-deleted strain E. coli JH15 simultaneously utilized pentose and hexose to complete the fermentation;however, the control strain started to utilize the xylose only after glucose was consumed up, and 18 g/L xylose still remained after the fermentation completed. The production of D-lactic acid by JH15 reached 83.04 g/L, and 25.86% higher than that by control strain JH13. The JH15 as a E. coli strain of producing D-lactic acid during simultaneous fermentation with mixed sugars, its construction provides a reference for producing the D-lactic acid in fermentation while utilizing the low-cost hydrolyzed components of lignocelluloses materials as raw material.