The effects of differing concentrations of CO2 and O2 on the fermentative metabolism of the rumen fungi Neocallimastix patriciarum and Neocallimastix frontalis L2

Elizabeth M R Rees, David Lloyd, Alan G. Williams

    Research output: Contribution to journalArticle

    2 Citations (Scopus)

    Abstract

    The effects of decreasing the concentration of CO2 and introducing up to 10% O2 into the headspace gases on the fermentative metabolism of the rumen fungi Neocallimastix patriciarum and Neocallimastix frontalis L2 were investigated. The relative proportion of metabolites produced by both fungi depended on the concentration of CO2 in the headspace. Under lowered CO2 levels, both fungi produced increased acetate, lactate, and H2, whereas the production of ethanol, formate, and (in the case of N. frontalis L2) succinate decreased. Lowered CO2 concentrations also decreased the rate of glucose utilization and cumulative gas production by both fungal isolates. In addition, decreased CO2 levels resulted in decreases in NAD(P)H ferredoxin oxidoreductase and hydrogenase activities, whereas malate dehydrogenase and pyruvate ferredoxin oxidoreductase activities were increased. Both N. patriciarum and N. frontalis L2 required at least 7% CO2 in the gas phase for growth. Both isolates also showed a degree of aerotolerance as they grew when exposed to 5% O2; they also grew in media lacking a reducing agent, providing that O2 was initially <1% of the total headspace concentration.

    Original languageEnglish
    Pages (from-to)819-824
    Number of pages6
    JournalCanadian Journal of Microbiology
    Volume44
    Issue number9
    DOIs
    Publication statusPublished - 1998

    Keywords

    • Carbon dioxide
    • Metabolism
    • Neocallimastix
    • Oxygen
    • Rumen fungi

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