earticle

영어

Polylactic acid (PLA) is a promising biomass-derived polymer, but is currently synthesized by a two-step process: fermentative production of lactic acid followed by chemical polymerization. Here we report production of PLA homopolymer and its copolymer, poly(3-hydroxybutyrate-co-lactate), P(3HB-co-LA), by direct fermentation of metabolically engineered Escherichia coli. Introduction of the heterologous metabolic pathways involving engineered propionate CoA-transferase and polyhydroxyalkanoate (PHA) synthase for the efficient generation of lactyl-CoA and incorporation of lactyl-CoA into the polymer, respectively, allowed synthesis of PLA and P(3HB-co-LA) in E. coli, but at relatively low efficiency1. In this study, the metabolic pathways of E. coli were further engineered based on in silico genome-scale metabolic flux analysis in
addition to rational approach2. Using this engineered strain, PLA homopolymer and P(3HB-co-LA)
copolymers containing up to 70 mol% lactate could be produced up to 11 wt% and 46 wt% from glucose, respectively. Thus, the combined approaches of systems-level metabolic engineering and enzyme engineering allowed efficient bio-based one-step production of PLA and its opolymers. This work was supported by LG Chem and by the Korean Systems Biology Research Project (20090065571) of the Ministry of Education, Science and Technology. Further supports by the LG Chem Chair Professorship, Microsoft, and IBM SUR, WCU (World Class University) program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology (R32-2008-000-10142-0) program are appreciated.