调整葡萄糖转运系统提高大肠杆菌L-苏氨酸产量

Adjusting the Glucose Transport System to Increase L-Threonine Production in Escherichia coli

摘要:

葡萄糖的有效利用是提高大肠杆菌合成L-苏氨酸能力的关键，作者通过优化葡萄糖转运来提高大肠杆菌L-苏氨酸合成能力。利用CRISPR基因编辑技术在大肠杆菌TWF001中分别敲除了PTS系统关键基因ptsH和ptsG，并在30 g/L葡萄糖质量浓度下进行了摇瓶发酵。与对照菌株TWF001相比，TWF001ΔptsH和TWF001ΔptsG合成L-苏氨酸能力均有明显改善；TWF001ΔptsH L-苏氨酸产量提升38.02%。在TWF001ΔptsH基因组上用trc启动子过表达galP基因，构建了TWF001ΔptsH，Ptrc：：PgalP。对3株突变菌在40、50、60 g/L葡萄糖质量浓度下进行了摇瓶发酵；36 h后TWF001ΔptsH，Ptrc：：PgalP在40 g/L葡萄糖质量浓度时，L-苏氨酸产量达到26.16 g/L，糖酸转化率为0.65 g/g，L-苏氨酸产量提升幅度达42.12%。研究结果说明优化葡萄糖转运可以有效提高大肠杆菌L-苏氨酸合成能力。

Abstract:

In this study, the improvement of L-threonine synthesis in E. coli was achieved by optimizing transport of glucose. The CRISPR gene-editing method was used to delete the key genes ptsH and ptsG in the PTS system. The flask fermentation was carried out under 30 g/L glucose.Compared with the control strain TWF001, the productivity of L-threonine synthesis was significantly improved in either TWF001ΔptsH or TWF001ΔptsG, and the L-threonine yield of TWF001ΔptsH increased 38.02%. The strains TWF001ΔptsH, Ptrc::PgalP were successfully constructed via the enhancement of galP expression though adding the trc promoter in TWF001ΔptsH genome.Three mutant strains were grown by flask fermentation under 40, 50 or 60 g/L glucose, respectively. The fermentation yield of L-threonine in TWF001ΔptsH, Ptrc::PgalP after 36 h increased by 42.12%, which was 26.16 g/L with a sugar acid conversion rate of 0.65 g/g. The modification of glucose transport was confirmed to effectively improve L-threonine synthesis in E. coli.