Applied Microbiology and Biotechnology

, Volume 93, Issue 1, pp 273–283

Biosynthesis of polyhydroxyalkanoates containing 2-hydroxybutyrate from unrelated carbon source by metabolically engineered Escherichia coli

  • Si Jae Park
  • Tae Woo Lee
  • Sung-Chul Lim
  • Tae Wan Kim
  • Hyuk Lee
  • Min Kyung Kim
  • Seung Hwan Lee
  • Bong Keun Song
  • Sang Yup Lee
Applied genetics and molecular biotechnology

DOI: 10.1007/s00253-011-3530-x

Cite this article as:
Park, S.J., Lee, T.W., Lim, SC. et al. Appl Microbiol Biotechnol (2012) 93: 273. doi:10.1007/s00253-011-3530-x

Abstract

We have previously reported in vivo biosynthesis of polylactic acid (PLA) and poly(3-hydroxybutyrate-co-lactate) [P(3HB-co-LA)] employing metabolically engineered Escherichia coli strains by the introduction of evolved Clostridium propionicum propionyl-CoA transferase (PctCp) and Pseudomonas sp. MBEL 6-19 polyhydroxyalkanoate (PHA) synthase 1 (PhaC1Ps6-19). Using this in vivo PLA biosynthesis system, we presently report the biosynthesis of PHAs containing 2-hydroxybutyrate (2HB) monomer by direct fermentation of a metabolically engineered E. coli strain. The recombinant E. coli ldhA mutant XLdh strain expressing PhaC1Ps6-19 and PctCp was developed and cultured in a chemically defined medium containing 20 g/L of glucose and varying concentrations of 2HB and 3HB. PHAs consisting of 2HB, 3HB, and a small fraction of lactate were synthesized. Their monomer compositions were dependent on the concentrations of 2HB and 3HB added to the culture medium. Even though the ldhA gene was completely deleted in the chromosome of E. coli, up to 6 mol% of lactate was found to be incorporated into the polymer depending on the culture condition. In order to synthesize PHAs containing 2HB monomer without feeding 2HB into the culture medium, a heterologous metabolic pathway for the generation of 2HB from glucose was constructed via the citramalate pathway, in which 2-ketobutyrate is synthesized directly from pyruvate and acetyl-CoA. Introduction of the Lactococcus lactis subsp. lactis Il1403 2HB dehydrogenase gene (panE) into E. coli allowed in vivo conversion of 2-ketobutyrate to 2HB. The metabolically engineered E. coli XLdh strain expressing the phaC1437, pct540, cimA3.7, and leuBCD genes together with the L. lactis Il1403 panE gene successfully produced PHAs consisting of 2HB, 3HB, and a small fraction of lactate by varying the 3HB concentration in the culture medium. As the 3HB concentration in the medium increased the 3HB monomer fraction in the polymer, the polymer content increased. When Ralstonia eutropha phaAB genes were additionally expressed in this recombinant E. coli XLdh strain, P(2HB-co-3HB-co-LA) having small amounts of 2HB and LA monomers could also be produced from glucose as a sole carbon source. The metabolic engineering strategy reported here should be useful for the production of PHAs containing 2HB monomer.

Keywords

Polyhydroxyalkanoate (PHA)2-hydroxybutyrate (2HB)PHA synthaseRecombinant E. coli

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Si Jae Park
    • 1
  • Tae Woo Lee
    • 2
  • Sung-Chul Lim
    • 4
  • Tae Wan Kim
    • 5
  • Hyuk Lee
    • 6
  • Min Kyung Kim
    • 2
  • Seung Hwan Lee
    • 1
  • Bong Keun Song
    • 1
  • Sang Yup Lee
    • 2
    • 3
  1. 1.Chemical Biotechnology Research CenterKorea Research Institute of Chemical TechnologyDaejeonRepublic of Korea
  2. 2.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 BioCenturyDaejeonRepublic of Korea
  3. 3.Department of Bio and Brain Engineering, Department of Biological SciencesBioProcess Engineering Research Center and Bioinformatics Research CenterDaejeonRepublic of Korea
  4. 4.Corporate R&D, LG Chem Research ParkDaejeonRepublic of Korea
  5. 5.Marine Biotechnology Research CenterKorea Ocean Research & Development InstituteAnsanRepublic of Korea
  6. 6.Medicinal Chemistry Research CenterKorea Research Institute of Chemical TechnologyDaejeonRepublic of Korea