NADH reoxidation does not control glycolytic flux during exposure of respiring Saccharomyces cerevisiae cultures to glucose excess

Authors

  • L Brambilla,

    1. Dipartimento di Fisiologia e Biochimica Generali, Sezione Biochimica Comparata, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
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  • D Bolzani,

    1. Dipartimento di Fisiologia e Biochimica Generali, Sezione Biochimica Comparata, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
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  • C Compagno,

    1. Dipartimento di Fisiologia e Biochimica Generali, Sezione Biochimica Comparata, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
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  • V Carrera,

    1. Dipartimento di Fisiologia e Biochimica Generali, Sezione Biochimica Comparata, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
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  • J.P van Dijken,

    1. Kluyver Laboratory of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
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  • J.T Pronk,

    1. Kluyver Laboratory of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
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  • B.M Ranzi,

    1. Dipartimento di Fisiologia e Biochimica Generali, Sezione Biochimica Comparata, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
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  • L Alberghina,

    1. Dipartimento di Fisiologia e Biochimica Generali, Sezione Biochimica Comparata, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
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  • D Porro

    Corresponding author
    1. Dipartimento di Fisiologia e Biochimica Generali, Sezione Biochimica Comparata, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
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*Corresponding author. Tel.: +39 (2) 70644801; Fax: +39 (2) 70632811; E-mail: porrod@imiucca.csi.unimi.it

Abstract

Introduction of the Lactobacillus casei lactate dehydrogenase (LDH) gene into Saccharomyces cerevisiae under the control of the TPI1 promoter yielded high LDH levels in batch and chemostat cultures. LDH expression did not affect the dilution rate above which respiro-fermentative metabolism occurred (Dc) in aerobic, glucose-limited chemostats. Above Dc, the LDH-expressing strain produced both ethanol and lactate, but its overall fermentation rate was the same as in wild-type cultures. Exposure of respiring, LDH-expressing cultures to glucose excess triggered simultaneous ethanol and lactate production. However, the specific glucose consumption rate was not affected, indicating that NADH reoxidation does not control glycolytic flux under these conditions.

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