Engineering the pentose phosphate pathway to improve hydrogen yield in recombinant Escherichia coli

Authors

  • Young Mi Kim,

    1. School of Environmental Science and Engineering, Pohang University of Science and Technology, San 31, Hyoja-Dong, Pohang 790-784, Korea; telephone: +82 54 279 2275; fax: +82 54 279 8299
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  • Han-Saem Cho,

    1. Department of Chemical Engineering, Pohang University of Science and Technology, San 31, Hyoja-Dong, Pohang 790-784, Korea; telephone: +82 54 279 2391; fax: +82 54 279 2699
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  • Gyoo Yeol Jung,

    Corresponding author
    1. Department of Chemical Engineering, Pohang University of Science and Technology, San 31, Hyoja-Dong, Pohang 790-784, Korea; telephone: +82 54 279 2391; fax: +82 54 279 2699
    2. School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, San 31, Hyoja-Dong, Pohang 790-784, Korea
    • Department of Chemical Engineering, Pohang University of Science and Technology, San 31, Hyoja-Dong, Pohang 790-784, Korea; telephone: +82 54 279 2391; fax: +82 54 279 2699.
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  • Jong Moon Park

    Corresponding author
    1. School of Environmental Science and Engineering, Pohang University of Science and Technology, San 31, Hyoja-Dong, Pohang 790-784, Korea; telephone: +82 54 279 2275; fax: +82 54 279 8299
    2. Department of Chemical Engineering, Pohang University of Science and Technology, San 31, Hyoja-Dong, Pohang 790-784, Korea; telephone: +82 54 279 2391; fax: +82 54 279 2699
    3. Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, San 31, Hyoja-Dong, Pohang 790-784, Korea
    • School of Environmental Science and Engineering, Pohang University of Science and Technology, San 31, Hyoja-Dong, Pohang 790-784, Korea; telephone: +82 54 279 2275; fax: +82 54 279 8299.
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Abstract

Among various routes for the biological hydrogen production, the NAD(P)H-dependent pentose phosphate (PP) pathway is the most efficient for the dark fermentation. Few studies, however, have focused on the glucose-6-phosphate 1-dehydrogenase, encoded by zwf, as a key enzyme activating the PP pathway. Although the gluconeogenic activity is essential for activating the PP pathway, it is difficult to enhance the NADPH production by regulating only this activity because the gluconeogenesis is robust and highly sensitive to concentrations of glucose and AMP inside the cell. In this study, the FBPase II (encoded by glpX), a regulation-insensitive enzyme in the gluconeogenic pathway, was activated. Physiological studies of several recombinant, ferredoxin-dependent hydrogenase system-containing Escherichia coli BL21(DE3) strains showed that overexpression of glpX alone could increase the hydrogen yield by 1.48-fold compared to a strain with the ferredoxin-dependent hydrogenase system only; the co-overexpression of glpX with zwf increased the hydrogen yield further to 2.32-fold. These results indicate that activation of the PP pathway by glpX overexpression-enhanced gluconeogenic flux is crucial for the increase of NAD(P)H-dependent hydrogen production in E. coli BL21(DE3). Biotechnol. Bioeng. 2011;108: 2941–2946. © 2011 Wiley Periodicals, Inc.

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