%0 Journal Article
%T Hyperactive nanobacteria with host-dependent traits pervade Omnitrophota.
%A Seymour CO
%A Palmer M
%A Becraft ED
%A Stepanauskas R
%A Friel AD
%A Schulz F
%A Woyke T
%A Eloe-Fadrosh E
%A Lai D
%A Jiao JY
%A Hua ZS
%A Liu L
%A Lian ZH
%A Li WJ
%A Chuvochina M
%A Finley BK
%A Koch BJ
%A Schwartz E
%A Dijkstra P
%A Moser DP
%A Hungate BA
%A Hedlund BP
%J Nat Microbiol
%V 8
%N 4
%D 04 2023
%M 36928026
%F 30.964
%R 10.1038/s41564-022-01319-1
%X Candidate bacterial phylum Omnitrophota has not been isolated and is poorly understood. We analysed 72 newly sequenced and 349 existing Omnitrophota genomes representing 6 classes and 276 species, along with Earth Microbiome Project data to evaluate habitat, metabolic traits and lifestyles. We applied fluorescence-activated cell sorting and differential size filtration, and showed that most Omnitrophota are ultra-small (~0.2 μm) cells that are found in water, sediments and soils. Omnitrophota genomes in 6 classes are reduced, but maintain major biosynthetic and energy conservation pathways, including acetogenesis (with or without the Wood-Ljungdahl pathway) and diverse respirations. At least 64% of Omnitrophota genomes encode gene clusters typical of bacterial symbionts, suggesting host-associated lifestyles. We repurposed quantitative stable-isotope probing data from soils dominated by andesite, basalt or granite weathering and identified 3 families with high isotope uptake consistent with obligate bacterial predators. We propose that most Omnitrophota inhabit various ecosystems as predators or parasites.