title: Phylogeny: are methanogens a third class of life?
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000378:metabolism; D001483:Base Sequence; D008697:Methane / Q000378:metabolism*; D010802:Phylogeny; D012329:RNA, Bacterial / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism
chemical_list: D012329:RNA, Bacterial; D012343:RNA, Transfer; D008697:Methane