Methanogenesis in granular sludge exposed to oxygen

Mario T. Kato, Jim A. Field, Gatze Lettinga

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


Substrate competition between methanogenic and facultative bacteria under highly aerobic conditions was investigated in batch experiments. Natural mixed cultures of anaerobic bacteria immobilized in granular sludge were able to concurrently utilize oxygen and produce methane when supplied with ethanol as substrate. The most oxygen tolerant sludge converted 3 to 25% of substrate chemical oxygen demand to methane after 3 days while 23 to 2 mg 1-1 of dissolved oxygen were present in the media. The tolerance of methanogens to oxygen and their coexistence with facultative bacteria were evident even after long periods of oxygen exposure. Eventually, methane oxidizing bacteria developed in the co-culture. The consumption of oxygen by facultative bacteria, creating anaerobic microniches inside the granules, is hypothesized to protect the methanogens.

Original languageEnglish (US)
Pages (from-to)317-323
Number of pages7
JournalFEMS Microbiology Letters
Issue number3
StatePublished - Dec 15 1993


  • Anaerobic methanogenic and aerobic facultative bacteria
  • Co-culture
  • Methanogens
  • Substrate competition

ASJC Scopus subject areas

  • General Medicine


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