Escherichia coli W as a new platform strain for the enhanced production of L-Valine by systems metabolic engineering

Authors

  • Jin Hwan Park,

    1. Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical and Biomolecular Engineering (BK21 Program), KAIST, Daejeon 305-701, Republic of Korea; tel.: +82-42-869-3930; fax: +82-42-869-3910,
    2. Center for Systems and Synthetic Biotechnology, Institute for the BioCentury, KAIST, Daejeon 305-701, Republic of Korea
    3. BioProcess Engineering Research Center, KAIST, Daejeon 305-701, Republic of Korea
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  • Yu-Sin Jang,

    1. Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical and Biomolecular Engineering (BK21 Program), KAIST, Daejeon 305-701, Republic of Korea; tel.: +82-42-869-3930; fax: +82-42-869-3910,
    2. Center for Systems and Synthetic Biotechnology, Institute for the BioCentury, KAIST, Daejeon 305-701, Republic of Korea
    3. BioProcess Engineering Research Center, KAIST, Daejeon 305-701, Republic of Korea
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  • Jeong Wook Lee,

    1. Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical and Biomolecular Engineering (BK21 Program), KAIST, Daejeon 305-701, Republic of Korea; tel.: +82-42-869-3930; fax: +82-42-869-3910,
    2. Center for Systems and Synthetic Biotechnology, Institute for the BioCentury, KAIST, Daejeon 305-701, Republic of Korea
    3. BioProcess Engineering Research Center, KAIST, Daejeon 305-701, Republic of Korea
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  • Sang Yup Lee

    1. Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical and Biomolecular Engineering (BK21 Program), KAIST, Daejeon 305-701, Republic of Korea; tel.: +82-42-869-3930; fax: +82-42-869-3910,
    2. Center for Systems and Synthetic Biotechnology, Institute for the BioCentury, KAIST, Daejeon 305-701, Republic of Korea
    3. BioProcess Engineering Research Center, KAIST, Daejeon 305-701, Republic of Korea
    4. Department of Bio and Brain Engineering, KAIST, Daejeon 305-701, Republic of Korea
    5. Department of Biological Sciences, and Bioinformatics Research Center, KAIST, Daejeon 305-701, Republic of Korea
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Abstract

A less frequently employed Escherichia coli strain W, yet possessing useful metabolic characteristics such as less acetic acid production and high L-valine tolerance, was metabolically engineered for the production of L-valine. The ilvA gene was deleted to make more pyruvate, a key precursor for L-valine, available for enhanced L-valine biosynthesis. The lacI gene was deleted to allow constitutive expression of genes under the tac or trc promoter. The ilvBNmut genes encoding feedback-resistant acetohydroxy acid synthase (AHAS) I and the L-valine biosynthetic ilvCED genes encoding acetohydroxy acid isomeroreductase, dihydroxy acid dehydratase, and branched chain amino acid aminotransferase, respectively, were amplified by plasmid-based overexpression. The global regulator Lrp and L-valine exporter YgaZH were also amplified by plasmid-based overexpression. The engineered E. coli W (ΔlacI ΔilvA) strain overexpressing the ilvBNmut, ilvCED, ygaZH, and lrp genes was able to produce an impressively high concentration of 60.7 g/L L-valine by fed-batch culture in 29.5 h, resulting in a high volumetric productivity of 2.06 g/L/h. The most notable finding is that there was no other byproduct produced during L-valine production. The results obtained in this study suggest that E. coli W can be a good alternative to Corynebacterium glutamicum and E. coli K-12, which have so far been the most efficient L-valine producer. Furthermore, it is expected that various bioproducts including other amino acids might be more efficiently produced by this revisited platform strain of E. coli. Bioeng. 2011; 108:1140–1147. © 2010 Wiley Periodicals, Inc.

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