Isolation of key methanogens for global methane emission from rice paddy fields: a novel isolate affiliated with the clone cluster rice cluster I.
Appl Environ Microbiol, 2007/7;73(13):4326-31.
Sakai S[1], Imachi H, Sekiguchi Y, Ohashi A, Harada H, Kamagata Y
Affiliations
PMID: 17483259
Impact factor: 5.005
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 H(2)-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.
MeSH terms
Archaea; Base Sequence; DNA, Archaeal; Ecosystem; Hydrogen; Methane; Molecular Sequence Data; Oryza; Phylogeny; RNA, Archaeal; RNA, Ribosomal, 16S; Soil Microbiology
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