Glucose metabolism in Lactococcus lactis MG1363 under different aeration conditions: Requirement of acetate to sustain growth under microaerobic conditions

Mikkel Nordkvist, N.B.S. Jensen, John Villadsen

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    Lactococcus lactis subsp. lactis MG1363 was grown in batch cultures on a defined medium with glucose as the energy source under different aeration conditions, namely, anaerobic conditions, aerobic conditions, and microaerobic conditions with a dissolved oxygen tension of 5% (when saturation with air was used as the reference). The maximum specific growth rate was high (0.78 to 0.91 h(-1)) under all aeration conditions but decreased with increasing aeration, and more than 90% of the glucose was converted to lactate. However, a shift in by-product formation was observed. Increasing aeration resulted in acetate, CO2, and acetoin replacing formate and ethanol as end products. Under microaerobic conditions, growth came to a gradual halt, although more than 60% of the glucose was still left. A decline in growth was not observed during microaerobic cultivation when acetate was added to the medium. We hypothesize that the decline in growth was due to a lack of acetyl coenzyme A (acetyl-CoA) needed for fatty acid synthesis since acetyl-CoA can be synthesized from acetate by means of acetate kinase and phosphotransacetylase activities.
    Original languageEnglish
    JournalApplied and Environmental Microbiology
    Volume69
    Issue number6
    Pages (from-to)3462-3468
    ISSN0099-2240
    Publication statusPublished - 2003

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