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文章摘要
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 of Escherichia coli
投稿时间:2019-04-01  修订日期:2019-06-03
DOI:
中文关键词: 大肠杆菌  L-苏氨酸;PTS系统;Galp;ptsH  ptsG
英文关键词: Escherichia coli, L-threonine, PTS, GalP ,ptsH, ptsG
基金项目:
作者单位E-mail
朱丽飞 食品科学与技术国家重点实验室 江南大学 2305255954@qq.com 
王小元 食品科学与技术国家重点实验室 江南大学 xiaoyuanwang@hotmail.com 
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中文摘要:
      大肠杆菌PTS系统和Galp蛋白在葡萄糖转运方面起着重要作用;PTS系统在转运过程中需要消耗关键代谢物PEP,而Galp蛋白不需要。考虑到PEP是L-苏氨酸合成的前体,本研究通过削弱PTS系统并加强galP表达来提高大肠杆菌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、40、50和60 g/L葡萄糖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-苏氨酸产量提升高达38.02%。进一步在TWF001ΔptsH基因组上用trc启动子过表达galP基因,构建了TWF001ΔptsH,Ptrc::PgalP;摇瓶发酵36小时,L-苏氨酸产量达到26.16 g/L,糖酸转化率为达0.65 g/g。与对照菌株TWF001相比,TWF001ΔptsH,Ptrc::PgalP L-苏氨酸产量提升幅度42.12%。本研究结果说明关闭PTS系统同时加强Galp葡萄糖转运可以有效提高大肠杆菌L-苏氨酸合成能力。
英文摘要:
      The PTS system and Galp protein of Escherichia coli play important roles in glucose transport. The PTS system consumes the key metabolite PEP during transport, while the Galp protein does not. Considering that PEP is the precursor of L-threonine synthesis, this study improved the L-threonine synthesis ability of E. coli by weakening the PTS system and enhancing galP expression. The key genes ptsH and ptsG of the PTS system were deleted in E. coli TWF001 using CRISPR gene editing technology, and the shaker fermentation was carried out at 30, 40, 50 and 60 g/L glucose concentrations. Compared with the control strain TWF001, the ability of L-threonine synthesis was improved significantly in TWF001ΔptsH and TWF001Δ ptsG, and the L-threonine yield of TWF001ΔptsH increased as high as 38.02%. Furthermore, galP gene was overexpressed by trc promoter in TWF001ΔptsH genome, constructed TWF001ΔptsH, Ptrc::PgalP. After 36 hours of flask fermentation, the L-threonine yield of TWF001ΔptsH, Ptrc::PgalP reached 26.16 g/L and the conversion rate reached 0.65 g/g. Compared with the control strain TWF001, the L - threonine yield of TWF001ΔptsH, Ptrc::PgalP increased by 42.12%. The results of this study suggested that shutting down the PTS system and strengthening Galp glucose transport can effectively improve the L-threonine synthesis ability of E. coli.
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