代谢工程改造克雷伯氏菌生产1,3-丙二醇

Metabolic engineering of Klebsiella pneumoniae for 1,3-propanediol production

摘要:

1,3-丙二醇是生产聚对苯二甲酸丙二醇酯(polytrimethylene terephthalate, PTT)的重要单体，目前主要通过微生物发酵法生产，但这种方法生产效率低下，限制了1,3-丙二醇的高效生物制造。为解决这一问题，本研究首先利用常压室温等离子(atmospheric room temperature plasma, ARTP)诱变技术，经过高通量筛选，成功获得了一株具有较高渗透压耐受性的菌株，其1,3-丙二醇产量达87 g/L。在此基础上，进一步筛选出了适合克雷伯氏菌的基因表达元件，并通过代谢工程改造，阻断冗余代谢支路(敲除ldhA、budA、aldA基因)，同时强化合成路径(过表达dhaB、yqhD基因)，使得改造后的工程克雷伯氏菌的1,3-丙二醇产量提升至107 g/L。最终，在5 L发酵罐中，通过优化发酵过程参数，最优工程菌株KP-FMME-6的1,3-丙二醇产量达到118 g/L，甘油转化率为42%，生产强度达到2.46 g/(h·L)。本研究为1,3-丙二醇的工业化生产提供了有效的借鉴和参考。

Abstract:

1,3-propanediol is an important monomer for the production of polytrimethylene terephthalate (PTT). Currently, it is mainly produced by microbial fermentation, which, however, has low production efficiency. To address this problem, this study employed atmospheric room temperature plasma (ARTP) mutagenesis technology and high-throughput screening to obtain a strain with high tolerance to osmotic pressure, which achieved a 1,3-propanediol titer of 87 g/L. Furthermore, the gene expression elements suitable for Klebsiella pneumoniae were screened, and metabolic engineering was employed to block redundant metabolic pathways (deletion of ldhA, budA, and aldA) and enhance the synthesis pathway (overexpression of dhaB and yqhD). The titer of 1,3-propanediol produced by the engineered strain increased to 107 g/L. Finally, in a 5 L fermenter, the optimal strain KP-FMME-6 achieved a 1,3-propanediol titer of 118 g/L, with a glycerol conversion rate of 42% and productivity of 2.46 g/(h·L), after optimization of the fermentation parameters. This study provides a reference for the industrial production of 1,3-propanediol.