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DePoy AN, King GM. Distribution and diversity of anaerobic thermophiles and putative anaerobic nickel-dependent carbon monoxide-oxidizing thermophiles in mesothermal soils and sediments. Front Microbiol 2023; 13:1096186. [PMID: 36699584 PMCID: PMC9868602 DOI: 10.3389/fmicb.2022.1096186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 12/15/2022] [Indexed: 01/11/2023] Open
Abstract
Even though thermophiles are best known from geothermal and other heated systems, numerous studies have demonstrated that they occur ubiquitously in mesothermal and permanently cold soils and sediments. Cultivation based studies of the latter have revealed that the thermophiles within them are mostly spore-forming members of the Firmicutes. Since the geographic distribution of spores is presumably unconstrained by transport through the atmosphere, similar communities (composition and diversity) of thermophiles might be expected to emerge in mesothermal habitats after they are heated. Alternatively, thermophiles might experience environmental selection before or after heating leading to divergent communities. After demonstrating the ubiquity of anaerobic thermophiles and CO uptake in a variety of mesothermal habitats and two hot springs, we used high throughput sequencing of 16S rRNA genes to assess the composition and diversity of populations that emerged after incubation at 60°C with or without headspace CO concentrations of 25%. Anaerobic Firmicutes dominated relative abundances at most sites but anaerobic thermophilic members of the Acidobacteria and Proteobacteria were also common. Nonetheless, compositions at the amplicon sequence variant (ASV) level varied among the sites with no convergence resulting from heating or CO addition as indicated by beta diversity analyses. The distinctions among thermophilic communities paralleled patterns observed for unheated "time zero" mesothermal soils and sediments. Occupancy analyses showed that the number of ASVs occupying each of n sites decreased unimodally with increasing n; no ASV occupied all 14 sites and only one each occupied 11 and 12 sites, while 69.3% of 1873 ASVs occupied just one site. Nonetheless, considerations of distances among the sites occupied by individual ASVs along with details of their distributions indicated that taxa were not dispersal limited but rather were constrained by environmental selection. This conclusion was supported by βMNTD and βNTI analyses, which showed dispersal limitation was only a minor contributor to taxon distributions.
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Yabe S, Muto K, Abe K, Yokota A, Staudigel H, Tebo BM. Vulcanimicrobium alpinus gen. nov. sp. nov., the first cultivated representative of the candidate phylum "Eremiobacterota", is a metabolically versatile aerobic anoxygenic phototroph. ISME COMMUNICATIONS 2022; 2:120. [PMID: 37749227 PMCID: PMC9758169 DOI: 10.1038/s43705-022-00201-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 11/07/2022] [Accepted: 11/10/2022] [Indexed: 09/27/2023]
Abstract
The previously uncultured phylum "Candidatus Eremiobacterota" is globally distributed and often abundant in oligotrophic environments. Although it includes lineages with the genetic potential for photosynthesis, one of the most important metabolic pathways on Earth, the absence of pure cultures has limited further insights into its ecological and physiological traits. We report the first successful isolation of a "Ca. Eremiobacterota" strain from a fumarolic ice cave on Mt. Erebus volcano (Antarctica). Polyphasic analysis revealed that this organism is an aerobic anoxygenic photoheterotrophic bacterium with a unique lifestyle, including bacteriochlorophyll a production, CO2 fixation, a high CO2 requirement, and phototactic motility using type IV-pili, all of which are highly adapted to polar and fumarolic environments. The cells are rods or filaments with a vesicular type intracytoplasmic membrane system. The genome encodes novel anoxygenic Type II photochemical reaction centers and bacteriochlorophyll synthesis proteins, forming a deeply branched monophyletic clade distinct from known phototrophs. The first cultured strain of the eighth phototrophic bacterial phylum which we name Vulcanimicrobium alpinus gen. nov., sp. nov. advances our understanding of ecology and evolution of photosynthesis.
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Affiliation(s)
- Shuhei Yabe
- Department of Microbial Resources, Graduate School of Agricultural Sciences, Tohoku University, Sendai, Miyagi, 980-0845, Japan.
- Hazaka Plant Research Center, Kennan Eisei Kogyo Co., Ltd., Sendai, Miyagi, 989-1311, Japan.
| | - Kiyoaki Muto
- Department of Microbial Resources, Graduate School of Agricultural Sciences, Tohoku University, Sendai, Miyagi, 980-0845, Japan
| | - Keietsu Abe
- Department of Microbial Resources, Graduate School of Agricultural Sciences, Tohoku University, Sendai, Miyagi, 980-0845, Japan
| | - Akira Yokota
- Department of Microbial Resources, Graduate School of Agricultural Sciences, Tohoku University, Sendai, Miyagi, 980-0845, Japan
| | - Hubert Staudigel
- Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, 92093, USA
| | - Bradley M Tebo
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195, USA
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