Lactic acid production by Candida sonorensis

Kari Koivuranta, Marja Ilmen, P. Suominen, Aristos Aristidou, V. Rajgarhia, Laura Ruohonen, Merja Penttilä

    Research output: Chapter in Book/Report/Conference proceedingConference abstract in proceedingsScientific

    Abstract

    C. sonorensis readily ferments glucose to ethanol, utilizes several carbon sources other than glucose, and is tolerant to acidic conditions. C. sonorensis was engineered for lactate production by individually expressing different lactate dehydrogenase genes in pyruvate decarboxylase positive and negative strain backgrounds to generate strains with distinctive characteristics. Production of lactate and ethanol from glucose was strongly affected by the deletions of the two pyruvate decarboxylase genes PDC1 and PDC2, the properties of the LDH enzymes, and by LDH enzyme activity which varied with LDH gene copy number. C. sonorensis LDH strains were also shown to ferment xylose to lactic acid efficiently via the endogenous xylose pathway enzymes, e.g. via xylose reductase and xylitol dehydrogenase. An alternative xylose fermentation pathway was introduced into C. sonorensis by expressing the XYLA gene from Piromyces sp. encoding xylose isomerase, and xylose was also shown to be metabolized via this pathway. Co-expression of the XKS1 gene from Saccharomyces cerevisiae encoding xylulokinase with the XYLA gene enhanced fermentation relative to expression of XYLA alone. Deletion of the endogenous reductase and xylitol dehydrogenase genes from a strain expressing xylose isomerase had a positive effect on lactate production from xylose.
    Original languageEnglish
    Title of host publication3rd European Federation of Biotechnology Conference
    Subtitle of host publicationPhysiology of Yeasts and Filamentous Fungi PYFF3
    Place of PublicationEspoo
    PublisherVTT Technical Research Centre of Finland
    Pages48
    ISBN (Electronic)978-951-38-6314-2
    ISBN (Print)978-951-38-6313-5
    Publication statusPublished - 2007
    Event3rd European Federation of Biotechnology Conference : Physiology of Yeasts and Filamentous Fungi - Helsinki, Finland
    Duration: 13 Jun 200716 Jun 2007

    Publication series

    SeriesVTT Symposium
    Number245
    ISSN0357-9387

    Conference

    Conference3rd European Federation of Biotechnology Conference
    Abbreviated titlePYFF3
    CountryFinland
    CityHelsinki
    Period13/06/0716/06/07

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