Engineered Escherichia coli for Short-Chain-Length Medium-Chain-Length Polyhydroxyalkanoate Copolymer Biosynthesis from Glycerol and Dodecanoate

摘要

Short-chain-length medium-chain-length polyhydroxyalkanoate (SCL-MCL PHA) copolymers are promising as bio-plastics with properties ranging from thermoplastics to elastomers. In this study, the hybrid pathway for the biosynthesis of SCL-MCL PHA copolymers was established in recombinant Escherichia coli by co-expression of β-ketothiolase (PhaA_(Re)) and NADPH-dependent acetoacetyl-CoA reductase (PhaB_(Re)) from Ralstonia eutropha together with PHA synthases from R. eutropha (PhaC_(Re)), Aeromonas hydrophila (PhaC_(Ah)), and Pseudomonas putida (PhaC2_(P_p)) and with (R) -specific enoyl-CoA hydratases from P. putida (PhaJ1_(p_p) and PhaJ4_(p_p)), and A. hydrophila (PhaJ_(Ah)). When glycerol supplemented with dodecanoate was used as primary carbon source, E. coli harboring various combinations of PhaABCJ produced SCL-MCL PHA copolymers of various monomer compositions varying from C4 to C_(10). In addition, polymer property analysis suggested that the copolymers produced from this recombinant source have thermal properties (lower glass transition and melting temperatures) superior to polyhydroxybutyrate homopolymer.