Improved L-lysine production with Corynebacterium glutamicum and systemic insight into citrate synthase flux and activity

Authors

  • Jan van Ooyen,

    1. Institute of Bio- and Geosciences, Biotechnology, Systemic Microbiology, Forschungszentrum Jülich GmbH, Jülich, Germany; telephone: +49-2461-61-5132; fax: +49-2461-61-5132
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  • Stephan Noack,

    1. Institute of Bio- and Geosciences, Biotechnology, Systems Biotechnology, Forschungszentrum Jülich GmbH, Jülich, Germany
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  • Michael Bott,

    1. Institute of Bio- and Geosciences, Biotechnology, Systemic Microbiology, Forschungszentrum Jülich GmbH, Jülich, Germany; telephone: +49-2461-61-5132; fax: +49-2461-61-5132
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  • Alexander Reth,

    1. Evonik Degussa GmbH, Halle/Westphalia, Germany
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  • Lothar Eggeling

    Corresponding author
    1. Institute of Bio- and Geosciences, Biotechnology, Systemic Microbiology, Forschungszentrum Jülich GmbH, Jülich, Germany; telephone: +49-2461-61-5132; fax: +49-2461-61-5132
    • Institute of Bio- and Geosciences, Biotechnology, Systemic Microbiology, Forschungszentrum Jülich GmbH, Jülich, Germany; telephone: +49-2461-61-5132; fax: +49-2461-61-5132.
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  • Jan van Ooyen and Stephan Noack have contributed equally to this work.

  • The authors have no conflict of interest to declare.

Abstract

We here developed a series of Corynebacterium glutamicum strains with gradual decreased specific citrate synthase (CS) activity and quantified in a multifaceted approach the consequences of residual activity on the transcriptome, metabolome, and fluxome level as well as on L-lysine formation and growth. We achieved an intended gradual L-lysine yield increase and recognized and overcame further new limitations in the L-lysine biosynthesis pathway to result in a strain with the highest yield reported so far when assayed under comparable conditions. As a non-intended outcome, a detailed flux analysis revealed an almost constant flux through CS at 10% remaining CS activity, whereas the metabolome data revealed an increase in the oxaloacetate and acetyl-CoA concentrations. Hence reduced CS activity is apparently efficiently buffered by increased concentrations of CS substrates, implying a certain robustness of the central metabolism in response of the imposed gene expressions. Biotechnol. Bioeng. 2012; 109:2070–2081. © 2012 Wiley Periodicals, Inc.

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