Diversity and taxonomic revision of methanogens and other archaea in the intestinal tract of terrestrial arthropods

• DOI: 10.3389/fmicb.2023.1281628
• Publication Date: 2023-11-15T09:51:37Z
• Authors: Evgenii Protasov; James O. Nonoh; Joana M. Kästle S...; Undine S. Mies; Vincent Hervé; Carsten Dietrich; Kristina Lang; Lena Mikulski; Katja Platt; Anja Poehlein; Tim Köhler-Ramm; Edouard Miambi; Hamadi I. Boga; Christopher Felde...; David K. Ngugi; Rudy Plarre; David Sillam-Dussès; Jan Šobotník; Rolf Daniel; Andreas Brune
• Keywords: Methanomicrobiales; Candidatus; Monophyly

Methane emission by terrestrial invertebrates is restricted to millipedes, termites, cockroaches, and scarab beetles. The arthropod-associated archaea known date belong the orders Methanobacteriales, Methanomassiliicoccales, Methanomicrobiales, Methanosarcinales, in a few cases also non-methanogenic Nitrososphaerales Bathyarchaeales. However, all major host groups are severely undersampled, taxonomy of existing lineages not well developed. Full-length 16S rRNA gene sequences genomes scarce, reference databases lack resolution, names many taxa either validly published or under-classified require revision. Here, we investigated diversity wide range methane-emitting arthropods, combining phylogenomic analysis isolates metagenome-assembled (MAGs) with amplicon sequencing full-length genes. Our results allowed us describe numerous new species hitherto undescribed among Methanobacteriales (Methanacia, Methanarmilla, Methanobaculum, Methanobinarius, Methanocatella, Methanoflexus, Methanorudis, Methanovirga, gen. nova), Methanomicrobiales (Methanofilum Methanorbis, both Methanosarcinales (Methanofrustulum Methanolapillus, Methanomassiliicoccales (Methanomethylophilaceae fam. nov., Methanarcanum, Methanogranum, Methanomethylophilus, Methanomicula, Methanoplasma, Methanoprimaticola, family Bathycorpusculaceae (Bathycorpusculum nov.). Reclassification libraries from this previous studies using taxonomic framework revealed that arthropods harbor only CO2 methyl-reducing hydrogenotrophic methanogens. Numerous genus-level appear be present exclusively suggesting long evolutionary trajectories their termite, cockroach, millipede hosts, radiation into various microhabitats ecological niches provided digestive tracts (e.g., hindgut compartments, gut wall, anaerobic protists). distribution patterns different often complex, indicating mixed mode transmission parallel evolution invertebrate vertebrate-associated lineages.