Archives of Microbiology

, Volume 109, Issue 1–2, pp 147–151 | Cite as

The acetylene reduction technique as an assay for nitrogenase activity in the methane oxidizing bacterium Methylococcus capsulatus strain bath

  • Howard Dalton
  • Roger Whittenbury


The use of acetylene as a convenient assay substrate for nitrogenase in methane oxidising bacteria is complicated by the observation that it is a potent inhibitor of the methane monooxygenase enzyme in both whole cells and cell-free extracts. If the cells were provided with alternative oxidisable carbon substrates other than methane then nitrogen fixing cells would reduce acetylene to ethylene. Hydrogen gas also served as an oxidisable substrate in the assay. Nitrous oxide, which is reduced by nitrogenase to N2 and H2O, was not an inhibitor of methane monooxygenase function and could be used as a convenient assay substrate for nitrogenase. Reduction of both substrates by whole cells showed similar response to oxygen in the assay system and in this respect Methylococcus resembles other free living nitrogen fixing aerobes.

Key words

Acetylene reduction Methane monooxygenase Inhibition by acetylene Oxygen sensitivity Methylococcus capsulatus 


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Copyright information

© Springer-Verlag 1976

Authors and Affiliations

  • Howard Dalton
    • 1
  • Roger Whittenbury
    • 1
  1. 1.Department of Biological SciencesUniversity of WarwickCoventryEngland

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