Identification and Overexpression of a Bifunctional Aldehyde/Alcohol Dehydrogenase Responsible for Ethanol Production in Thermoanaerobacter mathranii

Shuo Yao, Marie Just Mikkelsen

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    Thermoanaerobacter mathranii contains four genes, adhA, adhB, bdhA and adhE, predicted to code for alcohol dehydrogenases involved in ethanol metabolism. These alcohol dehydrogenases were characterized as NADP(H)-dependent primary alcohol dehydrogenase (AdhA), secondary alcohol dehydrogenase (AdhB), butanol dehydrogenase (BdhA) and NAD(H)-dependent bifunctional aldehyde/alcohol dehydrogenase (AdhE), respectively. Here we observed that AdhE is an important enzyme responsible for ethanol production in T. mathranii based on the constructed adh knockout strains. An adhE knockout strain fails to produce ethanol as a fermentation product, while other adh knockout strains showed no significant difference from the wild type. Further analysis revealed that the ΔadhE strain was defective in aldehyde dehydrogenase activity, but still maintained alcohol dehydrogenase activity. This showed that AdhE is the major aldehyde dehydrogenase in the cell and functions predominantly in the acetyl-CoA reduction to acetaldehyde in the ethanol formation pathway. Finally, AdhE was conditionally expressed from a xylose-induced promoter in a recombinant strain (BG1E1) with a concomitant deletion of a lactate dehydrogenase. Overexpressions of AdhE in strain BG1E1 with xylose as a substrate facilitate the production of ethanol at an increased yield. Copyright © 2010 S. Karger AG, Basel
    Original languageEnglish
    JournalJournal of Molecular Microbiology and Biotechnology
    Volume19
    Issue number3
    Pages (from-to)123-133
    ISSN1464-1801
    DOIs
    Publication statusPublished - 2010

    Keywords

    • Bio refinery
    • Bio systems

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