Engineering Escherichia coli for production of C12-C14 polyhydroxyalkanoate from glucose

Demand for sustainable materials motivates the development of microorganisms capable of synthesizing products from renewable substrates. A challenge to commercial production of polyhydroxyalkanoates (PHA), microbially derived polyesters, is engineering metabolic pathways to produce a polymer with the desired monomer composition from an unrelated and renewable source. Here, we demonstrate a metabolic pathway for converting glucose into medium-chain-length (mcl)-PHA composed primarily of 3-hydroxydodecanoate monomers. This pathway combines fatty acid biosynthesis, an acyl-ACP thioesterase to generate desired C-12 and C-14 fatty acids, beta-oxidation for conversion of fatty acids to (R)-3-hydroxyacyl-CoAs, and a PHA polymerase. A key finding is that Escherichiacoli expresses multiple copies of enzymes involved in beta-oxidation under aerobic conditions. To produce polyhydroxydodecanoate, an acyl-ACP thioesterase (BTE), an enoyl-CoA hydratase (phaJ3), and mcl-PHA polymerase (phaC2) were overexpressed in E. coli Delta fadRABIJ. Yields were improved through expression of an acyl-CoA synthetase resulting in production over 15% CDW the highest reported production of mcl-PHA of a defined composition from an unrelated carbon source. (C) 2012 Elsevier Inc. All rights reserved.