title: Genome of Rice Cluster I archaea--the key methane producers in the rice rhizosphere.
abstract: Rice fields are a global source of the greenhouse gas methane, which is produced by methanogenic archaea, and by methanogens of Rice Cluster I (RC-I) in particular. RC-I methanogens are not yet available in pure culture, and the mechanistic reasons for their prevalence in rice fields are unknown. We reconstructed a complete RC-I genome (3.18 megabases) using a metagenomic approach. Sequence analysis demonstrated an aerotolerant, H2/CO2-dependent lifestyle and enzymatic capacities for carbohydrate metabolism and assimilatory sulfate reduction, hitherto unknown among methanogens. These capacities and a unique set of antioxidant enzymes and DNA repair mechanisms as well as oxygen-insensitive enzymes provide RC-I with a selective advantage over other methanogens in its habitats, thereby explaining the prevalence of RC-I methanogens in the rice rhizosphere.
authors.affiliation: Max-Planck-Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse, 35043 Marburg, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Erkel
authors.forename: Michael
authors.initials: M
authors.lastname: Kube
authors.forename: Richard
authors.initials: R
authors.lastname: Reinhardt
authors.forename: Werner
authors.initials: W
authors.lastname: Liesack
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000096:biosynthesis / Q000378:metabolism; D050260:Carbohydrate Metabolism; D004260:DNA Repair; D019605:Euryarchaeota / Q000145:classification / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D020745:Genome, Archaeal; D023281:Genomics; D006019:Glycolysis; D008697:Methane / Q000096:biosynthesis*; D017018:Methanomicrobiales / Q000145:classification / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D019640:Methanosarcinales / Q000145:classification / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D008969:Molecular Sequence Data; D012275:Oryza / Q000382:microbiology*; D018384:Oxidative Stress; D019289:Pyruvic Acid / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D013431:Sulfates / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism
chemical_list: D000596:Amino Acids; D013431:Sulfates; D013455:Sulfur; D019289:Pyruvic Acid; D008697:Methane