title: Engineering of Serine-Deamination pathway, Entner-Doudoroff pathway and pyruvate dehydrogenase complex to improve poly(3-hydroxybutyrate) production in Escherichia coli.
abstract: BACKGROUND
  Poly(3-hydroxybutyrate) (PHB), a biodegradable bio-plastic, is one of the most common homopolymer of polyhydroxyalkanoates (PHAs). PHB is synthesized by a variety of microorganisms as intracellular carbon and energy storage compounds in response to environmental stresses. Bio-based production of PHB from renewable feedstock is a promising and sustainable alternative to the petroleum-based chemical synthesis of plastics. In this study, a novel strategy was applied to improve the PHB biosynthesis from different carbon sources.
  
  
  RESULTS
  In this research, we have constructed E. coli strains to produce PHB by engineering the Serine-Deamination (SD) pathway, the Entner-Doudoroff (ED) pathway, and the pyruvate dehydrogenase (PDH) complex. Firstly, co-overexpression of sdaA (encodes L-serine deaminase), L-serine biosynthesis genes and pgk (encodes phosphoglycerate kinase) activated the SD Pathway, and the resulting strain SD02 (pBHR68), harboring the PHB biosynthesis genes from Ralstonia eutropha, produced 4.86 g/L PHB using glucose as the sole carbon source, representing a 2.34-fold increase compared to the reference strain. In addition, activating the ED pathway together with overexpressing the PDH complex further increased the PHB production to 5.54 g/L with content of 81.1% CDW. The intracellular acetyl-CoA concentration and the [NADPH]/[NADP(+)] ratio were enhanced after the modification of SD pathway, ED pathway and the PDH complex. Meanwhile, these engineering strains also had a significant increase in PHB concentration and content when xylose or glycerol was used as carbon source.
  
  
  CONCLUSIONS
  Significant levels of PHB biosynthesis from different kinds of carbon sources can be achieved by engineering the Serine-Deamination pathway, Entner-Doudoroff pathway and pyruvate dehydrogenase complex in E. coli JM109 harboring the PHB biosynthesis genes from Ralstonia eutropha. This work demonstrates a novel strategy for improving PHB production in E. coli. The strategy reported here should be useful for the bio-based production of PHB from renewable resources.
authors.affiliation: Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, People's Republic of China. zhangyan12@tju.edu.cn.|SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China. zhangyan12@tju.edu.cn.|Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, Tianjin, 300072, People's Republic of China. zhangyan12@tju.edu.cn.|Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China. zhangyan12@tju.edu.cn.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, People's Republic of China. zhenquanlin@tju.edu.cn.|SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China. zhenquanlin@tju.edu.cn.|Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, Tianjin, 300072, People's Republic of China. zhenquanlin@tju.edu.cn.|Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China. zhenquanlin@tju.edu.cn.
authors.forename: Zhenquan
authors.initials: Z
authors.lastname: Lin
authors.affiliation: Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, People's Republic of China. liuqiaojie@tju.edu.cn.|SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China. liuqiaojie@tju.edu.cn.|Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, Tianjin, 300072, People's Republic of China. liuqiaojie@tju.edu.cn.|Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China. liuqiaojie@tju.edu.cn.
authors.forename: Qiaojie
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, People's Republic of China. lyf0421@gmail.com.|SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China. lyf0421@gmail.com.|Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, Tianjin, 300072, People's Republic of China. lyf0421@gmail.com.|Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China. lyf0421@gmail.com.
authors.forename: Yifan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, People's Republic of China. zww@tju.edu.cn.|SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China. zww@tju.edu.cn.|Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, Tianjin, 300072, People's Republic of China. zww@tju.edu.cn.|Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China. zww@tju.edu.cn.
authors.forename: Zhiwen
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, People's Republic of China. ma_hw@tib.cas.cn.
authors.forename: Hongwu
authors.initials: H
authors.lastname: Ma
authors.affiliation: Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, People's Republic of China. chentao@tju.edu.cn.|SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China. chentao@tju.edu.cn.|Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, Tianjin, 300072, People's Republic of China. chentao@tju.edu.cn.|Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China. chentao@tju.edu.cn.
authors.forename: Tao
authors.initials: T
authors.lastname: Chen
authors.affiliation: Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, People's Republic of China. xmzhao@tju.edu.cn.|SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China. xmzhao@tju.edu.cn.|Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, Tianjin, 300072, People's Republic of China. xmzhao@tju.edu.cn.|Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China. xmzhao@tju.edu.cn.
authors.forename: Xueming
authors.initials: X
authors.lastname: Zhao
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D020118:Cupriavidus necator / Q000201:enzymology / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D006885:Hydroxybutyrates / Q000378:metabolism*; D012695:L-Serine Dehydratase / Q000096:biosynthesis / Q000235:genetics; D060847:Metabolic Engineering; D010735:Phosphoglycerate Kinase / Q000096:biosynthesis / Q000235:genetics; D011091:Polyesters / Q000378:metabolism*; D011768:Pyruvate Dehydrogenase Complex / Q000235:genetics / Q000378:metabolism; D000094122:Polyhydroxybutyrates
chemical_list: D001426:Bacterial Proteins; D006885:Hydroxybutyrates; D012695:L-Serine Dehydratase; D010735:Phosphoglycerate Kinase; D011091:Polyesters; D011768:Pyruvate Dehydrogenase Complex; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates