biostudies-literatureUnknown37(4)Kuroda KTo identify novel cross-domain symbiosis between Candidatus Patescibacteria and Archaea, we performed fluorescence in situ hybridization (FISH) on enrichment cultures derived from methanogenic bioreactor sludge with the newly designed 32-520-1066 probe targeting the family-level uncultured clade 32-520/UBA5633 lineage in the class Ca. Paceibacteria. All FISH-detectable 32-520/UBA5633 cells were attached to Methanospirillum, indicating high host specificity. Transmission electron microscopy observations revealed 32-520/UBA5633-like cells that were specifically adherent to the plug structure of Methanospirillum-like rod-shaped cells. The metagenome-assembled genomes of 32-520/UBA5633 encoded unique gene clusters comprising pilin signal peptides and type IV pilins. These results provide novel insights into unseen symbiosis between Ca. Patescibacteria and Archaea.Microbes and environmentshttps://www.ebi.ac.uk/biostudies/studies/S-EPMC9763046biostudies-literatureNovel Cross-domain Symbiosis between Candidatus Patescibacteria and Hydrogenotrophic Methanogenic Archaea Methanospirillum Discovered in a Methanogenic Ecosystem.PMC9763046Nobu MKKubota KYamamoto KHirakata YKagemasa SKuroda KNarihiro TNakai RfalseNovel Cross-domain Symbiosis between Candidatus Patescibacteria and Hydrogenotrophic Methanogenic Archaea Methanospirillum Discovered in a Methanogenic Ecosystem.To identify novel cross-domain symbiosis between Candidatus Patescibacteria and Archaea, we performed fluorescence in situ hybridization (FISH) on enrichment cultures derived from methanogenic bioreactor sludge with the newly designed 32-520-1066 probe targeting the family-level uncultured clade 32-520/UBA5633 lineage in the class Ca. Paceibacteria. All FISH-detectable 32-520/UBA5633 cells were attached to Methanospirillum, indicating high host specificity. Transmission electron microscopy observations revealed 32-520/UBA5633-like cells that were specifically adherent to the plug structure of Methanospirillum-like rod-shaped cells. The metagenome-assembled genomes of 32-520/UBA5633 encoded unique gene clusters comprising pilin signal peptides and type IV pilins. These results provide novel insights into unseen symbiosis between Ca. Patescibacteria and Archaea.2022-01-01T00:00:00Z20222025-04-05T12:09:30.782Z2025-04-05T12:09:30.782ZS-EPMC97630463637243210.1264/jsme2.ME22063