Isolation of key methanogens for global methane emission from rice paddy fields: A novel isolate affiliated with the clone cluster rice cluster

Sanae Sakai, Hiroyuki Imachi, Yuji Sekiguchi, Akiyoshi Ohashi, Hideki Harada, Yoichi Kamagata

Research output: Contribution to journalArticlepeer-review

85 Citations (Scopus)

Abstract

Despite the fact that rice paddy fields (RPFs) are contributing 10 to 25% of global methane emissions, the organisms responsible for methane production in RPFs have remained uncultivated and thus uncharacterized. Here we report the isolation of a methanogen (strain SANAE) belonging to an abundant and ubiquitous group of methanogens called rice cluster I (RC-I) previously identified as an ecologically important microbial component via culture-independent analyses. To enrich the RC-I methanogens from rice paddy samples, we attempted to mimic the in situ conditions of RC-I on the basis of the idea that methanogens in such ecosystems should thrive by receiving low concentrations of substrate (H 2) continuously provided by heterotrophic H2-producing bacteria. For this purpose, we developed a coculture method using an indirect substrate (propionate) in defined medium and a propionate-oxidizing, H 2-producing syntroph, Syntrophobacter fumaroxidans, as the H 2 supplier. By doing so, we significantly enriched the RC-I methanogens and eventually obtained a methanogen within the RC-I group in pure culture. This is the first report on the isolation of a methanogen within RC-I.

Original languageEnglish
Pages (from-to)4326-4331
Number of pages6
JournalApplied and environmental microbiology
Volume73
Issue number13
DOIs
Publication statusPublished - 2007 Jul

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

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