Author(s): Taguchi S, Yamada M, Matsumoto K, Tajima K, Satoh Y,
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Abstract Polylactate (PLA) is synthesized as a representative bio-based polyester by the chemo-bio process on the basis of metal catalyst-mediated chemical polymerization of lactate (LA) supplied by microbial fermentation. To establish the one-step microbial process for synthesis of LA-based polyesters, we explored whether polyhydroxyalkanoate (PHA) synthase would exhibit polymerizing activity toward a LA-coenzyme A (CoA), based on the fact that PHA monomeric constituents, especially 3-hydroxybutyrate (3HB), are structurally analogous to LA. An engineered PHA synthase was discovered as a candidate by a two-phase in vitro polymerization system previously developed. An LA-CoA producing Escherichia coli strain with a CoA transferase gene was constructed, and the generation of LA-CoA was demonstrated by capillary electrophoresis/MS analysis. Next, when the engineered PHA synthase gene was introduced into the resultant recombinant strain, we confirmed the one-step biosynthesis of the LA-incorporated copolyester, P(6 mol\% LA-co-94 mol\% 3HB), with a number-average molecular weight of 1.9 x 10(5), as revealed by gel permeation chromatography, gas chromatography/MS, and NMR.
This article was published in Proc Natl Acad Sci U S A
and referenced in Journal of Microbial & Biochemical Technology