Taxonomic revision of the genus Methanobrevibacter, description of Methanomonile shimae gen. nov. sp. nov., and proposal of Methanobrevibacteraceae fam. nov.

Recent phylogenomic analyses revealed that the genus Methanobrevibacter, which consists almost exclusively of representatives from the intestinal tract of animals, is severely underclassified. Based on the large relative evolutionary divergence between individual subclades, members of the genus Methanobrevibacter have been reclassified into eight novel genera as new combinations proposed under the rules of the Code of Nomenclature of Prokaryotes Described from Sequence Data. Here, we validly publish the new names for all taxa with type strains also under the rules of the International Code of Nomenclature of Prokaryotes. This includes members of the genera Methanacia, Methanobaculum, Methanobinarius, Methanocatella and Methanoflexus. Moreover, we propose to place Methanobrevibacter acididurans, whose genome was only recently sequenced, in the new genus Methanobotrus and describe a new isolate from the gut of a cockroach as Methanomonile shimae gen. nov. sp. nov. Based on the large evolutionary distance from the remaining members of Methanobacteriaceae, we propose to reclassify all genera within the radiation of Methanobrevibacter sensu lato into their own family, Methanobrevibacteraceae fam. nov. In addition, we reclassify Methanothermobacter tenebrarum as Methanothermobaculum tenebrarum gen. nov. comb. nov. into a new family, Methanothermobaculaceae (Methanobacteriales) and provide emended descriptions for the phylum Methanobacteriota and the classes Methanobacteria and Methanococci.