Advertisement

Biosynthesis of polylactic acid and its copolymers using evolved propionate CoA transferase and PHA synthase

Authors

  • Taek Ho Yang,

    1. Corporate R&D, LG Chem Research Park, 104-1 Moonji-dong, Yuseong-gu, Daejeon 305-380, Republic of Korea; telephone: +82-42-870-6442; fax: +82-42-861-2057
    Search for more papers by this author
  • Tae Wan Kim,

    1. Corporate R&D, LG Chem Research Park, 104-1 Moonji-dong, Yuseong-gu, Daejeon 305-380, Republic of Korea; telephone: +82-42-870-6442; fax: +82-42-861-2057
    Search for more papers by this author
  • Hye Ok Kang,

    1. Corporate R&D, LG Chem Research Park, 104-1 Moonji-dong, Yuseong-gu, Daejeon 305-380, Republic of Korea; telephone: +82-42-870-6442; fax: +82-42-861-2057
    Search for more papers by this author
  • Sang-Hyun Lee,

    1. Corporate R&D, LG Chem Research Park, 104-1 Moonji-dong, Yuseong-gu, Daejeon 305-380, Republic of Korea; telephone: +82-42-870-6442; fax: +82-42-861-2057
    Search for more papers by this author
  • Eun Jeong Lee,

    1. Corporate R&D, LG Chem Research Park, 104-1 Moonji-dong, Yuseong-gu, Daejeon 305-380, Republic of Korea; telephone: +82-42-870-6442; fax: +82-42-861-2057
    Search for more papers by this author
  • Sung-Chul Lim,

    1. Corporate R&D, LG Chem Research Park, 104-1 Moonji-dong, Yuseong-gu, Daejeon 305-380, Republic of Korea; telephone: +82-42-870-6442; fax: +82-42-861-2057
    Search for more papers by this author
  • Sun Ok Oh,

    1. Corporate R&D, LG Chem Research Park, 104-1 Moonji-dong, Yuseong-gu, Daejeon 305-380, Republic of Korea; telephone: +82-42-870-6442; fax: +82-42-861-2057
    Search for more papers by this author
  • Ae-Jin Song,

    1. Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical and Biomolecular Engineering (BK21 Program), Center for Systems and Synthetic Biotechnology, and Institute for the BioCentury, KAIST, 335 Gwahangno, Yuseong-gu, Daejeon 305-701, Republic of Korea; telephone: +82-42-350-3930; fax: +82-42-350-3910
    Search for more papers by this author
  • Si Jae Park,

    Corresponding author
    1. Corporate R&D, LG Chem Research Park, 104-1 Moonji-dong, Yuseong-gu, Daejeon 305-380, Republic of Korea; telephone: +82-42-870-6442; fax: +82-42-861-2057
    • Corporate R&D, LG Chem Research Park, 104-1 Moonji-dong, Yuseong-gu, Daejeon 305-380, Republic of Korea; telephone: +82-42-870-6442; fax: +82-42-861-2057.
    Search for more papers by this author
  • Sang Yup Lee

    Corresponding author
    1. Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical and Biomolecular Engineering (BK21 Program), Center for Systems and Synthetic Biotechnology, and Institute for the BioCentury, KAIST, 335 Gwahangno, Yuseong-gu, Daejeon 305-701, Republic of Korea; telephone: +82-42-350-3930; fax: +82-42-350-3910
    2. Department of Bio and Brain Engineering, Department of Biological Sciences, BioProcess Engineering Research Center, and Bioinformatics Research Center, KAIST, 335 Gwahangno, Yuseong-gu, Daejeon 305-701, Republic of Korea
    • Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical and Biomolecular Engineering (BK21 Program), Center for Systems and Synthetic Biotechnology, and Institute for the BioCentury, KAIST, 335 Gwahangno, Yuseong-gu, Daejeon 305-701, Republic of Korea; telephone: +82-42-350-3930; fax: +82-42-350-3910.
    Search for more papers by this author

Abstract

For the synthesis of polylactic acid (PLA) and its copolymers by one-step fermentation process, heterologous pathways involving Clostridium propionicum propionate CoA transferase (PctCp) and Pseudomonas sp. MBEL 6-19 polyhydroxyalkanoate (PHA) synthase 1 (PhaC1Ps6-19) were introduced into Escherichia coli for the generation of lactyl-CoA endogenously and incorporation of lactyl-CoA into the polymer, respectively. Since the wild-type PhaC1Ps6-19 did not efficiently accept lactyl-CoA as a substrate, site directed mutagenesis as well as saturation mutagenesis were performed to improve the enzyme. The wild-type PctCp was not able to efficiently convert lactate to lactyl-CoA and was found to exert inhibitory effect on cell growth, random mutagenesis by error-prone PCR was carried out. By employing engineered PhaC1Ps6-19 and PctCp, poly(3-hydroxybutyrate-co-lactate), P(3HB-co-LA), containing 20–49 mol% lactate could be produced up to 62 wt% from glucose and 3HB. By controlling the 3HB concentration in the medium, PLA homopolymer and P(3HB-co-LA) containing lactate as a major monomer unit could be synthesized. Also, P(3HB-co-LA) copolymers containing various lactate fractions could be produced from glucose alone by introducing the Cupriavidus necator β-ketothiolase and acetoacetyl-CoA reductase genes. Fed-batch cultures were performed to produce P(3HB-co-LA) copolymers having 9–64 mol% of lactate, and their molecular weights, thermal properties, and melt flow properties were determined. Biotechnol. Bioeng. 2010; 105: 150–160. © 2009 Wiley Periodicals, Inc.

Ancillary