Producing medium-chain-length polyhydroxyalkanoate from diverse feedstocks by deregulating unsaturated fatty acid biosynthesis in Escherichia coli

• phaG and phaC1 genes were heterologously expressed in E. coli . • The recombinant E. coli was able to produce poly(3-hydroxydecanoate). • A gene, PSEEN0908, was found to increase the performance of mcl-PHA production. • FabR substantially increased the mcl-PHA production by an order of magnitude. • The microbial catalysis of mcl-PHA can be derived from various bioresources. The fatty acid metabolism in Escherichia coli has served as a basic metabolic chassis for medium-chain-length polyhydroxyalkanoate (mcl-PHA) production. In this study, the phaG and phaC1 genes from Pseudomonas entomophila L48 were first cloned as pGRN08. E. coli BL21P ( E. coli BL21(DE3) Δ ptsG ) containing pGRN08 was able to produce 23±3 and 7±0 mg/L homopolymer poly(3-hydroxydecanoate)(P(3HD)) from glucose and xylose, respectively. Next, a gene, PSEEN0908 (encoding a putative 3-hydroxyacyl-CoA ligase), from P. entomophila L48 was found to increase the performance of mcl-PHA production. The induction of the fatty acid biosynthesis repressor (FabR), a transcription regulator that represses UFA biosynthesis, in E. coli substantially increased the mcl-PHA production by an order of magnitude from both unrelated and related carbon source conversion. A mcl-PHA concentration of 179±1 mg/L and a content of 5.79 ± 0.16 % were obtained, where 31 mol% was 3-hydroxyoctanoate (3HO) and 69 mol% was 3HD.