Poly(3-hydroxyalkanoates) (PHA) are a class of renewable and biodegradable polyesters that can be microbially synthesized in large quantity. It has been reported that more than 150 unique monomers can be incorporated into the PHA polymer to give rise to its versatile functionalities; therefore, demands for sustainable materials have recognized PHA as potential plastic alternatives. Due to the cost of related feedstocks (e.g., fatty acids and lipids), a challenge for large-scale PHA production is to produce polymers from cheaper and renewable feedstocks (e.g., sugars). Here, we demonstrate the production of poly(3-hydroxyoctanoic acid) (PHO) in recombinant Escherichia coli from glycerol via an engineered metabolic pathway that combines fatty acid biosynthesis and β-oxidation. We identified the combination of (R)-specific enoyl-CoA hydratase, PHA synthases, and acyl-CoA synthetase that are optimal for PHO production from exogenously fed octanoic acid as the sole carbon source. We showed that by over-expressing acyl-CoA dehydrogenase, PHO content can be further improved. Furthermore, when a single copy of a C8-specific Cuphea palustris FatB1 thioesterase mutant CpFatB1.2-M4-287 is integrated into the chromosome, the resulting E. coli strain is capable of producing &gt;1.3 g/L of octanoic acid with &gt;88% specificity from glycerol. Subsequent the expression of PHA synthesis genes allows a PHO production of ~15% cell-dry-weight (CDW) and ~1 g/L – the highest reported production of PHO from an unrelated carbon source.

Engineering Escherichia coli for production of poly(3-hydroxyoctanoic acid) from glycerol

2019 Spring National Meeting

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