Metabolic engineering of Escherichia coli for poly(3-hydroxybutyrate) production viathreonine bypass

Microbial Cell Factories

Research

Qiaojie Liu¹  Zhiwen Wang¹  Zhenquan Lin¹  Yan Zhang¹  Yifan Li¹  Xueming Zhao¹  Tao Chen²  Qianqian Yuan³  Hongwu Ma⁴ 

[1] Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, 300072, Tianjin, China;SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China;Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, 300072, Tianjin, China;Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, 300072, Tianjin, China;SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China;Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, 300072, Tianjin, China;Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Nankai District, 92 Weijin Road, 300072, Tianjin, China;Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, 300072, Tianjin, China;SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China;Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, 300072, Tianjin, China;Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 300308, Tianjin, China;Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 300308, Tianjin, China;

关键词: Genome-scale metabolic network;    Threonine bypass;    Strain optimization;    Poly(3-hydroxybutyrate);   

DOI  :  10.1186/s12934-015-0369-3

 received in 2015-09-06, accepted in 2015-10-27,  发布年份 2015

来源: Springer

【 摘 要 】

BackgroundPoly(3-hydroxybutyrate) (PHB), have been considered to be goodcandidates for completely biodegradable polymers due to their similar mechanicalproperties to petroleum-derived polymers and complete biodegradability.Escherichia coli has been used tosimulate the distribution of metabolic fluxes in recombinant E. coli producing poly(3-hydroxybutyrate) (PHB).Genome-scale metabolic network analysis can reveal unexpected metabolicengineering strategies to improve the production of biochemicals andbiofuels.ResultsIn this study, we reported the discovery of a new pathway calledthreonine bypass by flux balance analysis of the genome-scale metabolic model ofE. coli. This pathway, mainly containingthe reactions for threonine synthesis and degradation, can potentially increasethe yield of PHB and other acetyl-CoA derived products by reutilizing theCO2 released at the pyruvate dehydrogenase step. Toimplement the threonine bypass for PHB production in E.coli, we deregulated the threonine and serine degradation pathwayand enhanced the threonine synthesis, resulting in 2.23-fold improvement of PHBtiter. Then, we overexpressed glyA to enhancethe conversion of glycine to serine and activated transhydrogenase to generateNADPH required in the threonine bypass.ConclusionsThe result strain TB17 (pBHR68) produced 6.82 g/L PHB with the yieldof 0.36 g/g glucose in the shake flask fermentation and 35.92 g/L PHB with theyield of 0.23 g/g glucose in the fed-batch fermentation, which was almost3.3-fold higher than the parent strain. The work outlined here shows thatgenome-scale metabolic network analysis can reveal novel metabolic engineeringstrategies for developing efficient microbial cell factories.

【 授权许可】

CC BY   
© Lin et al 2015