Caldifarciminota is a phylum of bacteria from the kingdom Pseudomonadati, closely related to Cloacimonadota.[1] This lineage was identified as the candidate phylum WOR-3, based on metagenome-assembled genomes of samples from various environments. The earliest report of WOR-3 dates back to 1994.[2] The type species Caldifarcimen microaerophilum was isolated and described in 2026.[3]
| Caldifarciminota | |
|---|---|
Scientific classification  | |
| Domain: | Bacteria |
| Kingdom: | Pseudomonadati |
| Phylum: | Caldifarciminota Mori et al. 2026 |
| Type genus | |
| Caldifarcimen Mori et al. 2026 | |
| Classes | |
| Synonyms | |
| |
It is widely distributed in various environments, including hot springs, marine ecosystems, and hydrothermal vents, yet its ecological roles and metabolic capabilities remain poorly understood.[2]
Nomenclature
editThree candidate phylum names have been proposed for the WOR-3 lineage: the phylum "Candidatus Pyropristinus" was proposed for the MAG sequence of "Candidatus Caldipriscus" sp. T1.2 from the Bechler Spring microbial filament in Yellowstone National Park in 2016, the phylum "Candidatus Hydrothermae" was named after the representative MAG sequence of "Candidatus Hydrothermae pacifica" JdFR-72 retrieved from a Juan de Fuca Ridge flank subsurface fluid in 2017, and the phylum "Candidatus Stahlbacteria" was proposed for several MAG sequences belonging to the WOR-3 lineage in the absence of representatives in 2017.[4]
According to the International Code of Nomenclature of Prokaryotes these three candidate phylum names were later corrected to "Candidatus Caldipriscota", "Candidatus Hydrothermota", and "Candidatus Stahliibacteriota".[5]
The validly published name Caldifarciminota is based on the name of the species Caldifarcimen microaerophilum, a facultatively anaerobic, thermophilic, Gram-negative bacterium isolated from a deep-sea hydrothermal field in 2026.[6]
Etymology: The Latin adjective caldus means hot, the Latin neutrum farcimen means a sausage.[6]
Systematics
editThe currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN).[6]
The phylum Caldifarciminota includes two monotypic classes:
- class Caldifarciminia Mori et al. 2026 (synonym "Candidatus Hydrothermia" Chuvochina et al. 2023)
- order Caldifarciminales Mori et al. 2026
- family Caldifarciminaceae Mori et al. 2026
- genera Caldifarcimen Mori et al. 2026, "Candidatus Caldipriscus" Colman et al. 2016, "Candidatus Hydrothermus" Chuvochina et al. 2019, "Candidatus Thermoproauctor" Colman et al. 2016
- family Caldifarciminaceae Mori et al. 2026
- order Caldifarciminales Mori et al. 2026
- class "Candidatus Tepidihabitantia" Slobodkina et al. 2025
- order "Candidatus Tepidihabitantales" Slobodkina et al. 2025
- family "Candidatus Tepidihabitantaceae" Slobodkina et al. 2025
- genus "Candidatus Tepidihabitans" Slobodkina et al. 2025
- family "Candidatus Tepidihabitantaceae" Slobodkina et al. 2025
- order "Candidatus Tepidihabitantales" Slobodkina et al. 2025
References
edit- ↑ D. Parks; P. Chaumeil; A. Mussig. "GTDB Release 11-RS232 (15th April 2026). Species labels tree". GTDB. Australian Centre for Ecogenomics. Retrieved 2026-07-16.
- 1 2 Zeng, Jianxiong; Hu, Wenzhe; Chang, Licao; Hua, Zhengshuang; Wu, Geng; Fang, Yun; Wang, Guowei; Xiao, Chunqiao; Liu, Jun (22 October 2025). "Genome-resolved insights into the bacterial phylum WOR-3: hydrogenotrophic metabolism and unique carbon fixation via archaeal form III RuBisCO". mSystems. 10 (10) e01178-25. doi:10.1128/msystems.01178-25. PMC 12542636. PMID 41036842.
- ↑ Mori, Koji; Hidaka, Kohei; Tamazawa, Satoshi; Hosoyama, Akira; Tamaki, Hideyuki; Kakegawa, Takeshi; Hanada, Satoshi (3 July 2026). "Caldifarcimen microaerophilum gen. nov., sp. nov., a facultatively anaerobic, thermophilic bacterium of a novel bacterial phylum, Caldifarciminota phyl. nov., formerly called candidate phylum WOR-3, description of Caldifarciminaceae fam. nov., Caldifarciminales ord. nov. and Caldifarciminia classis nov". International Journal of Systematic and Evolutionary Microbiology. 76 (7). doi:10.1099/ijsem.0.007229. PMID 42397696.
- ↑ Mori, Koji; Hidaka, Kohei; Tamazawa, Satoshi; Hosoyama, Akira; Tamaki, Hideyuki; Kakegawa, Takeshi; Hanada, Satoshi (23 July 2025). "Isolation and characterization of a bacterium affiliated with the hitherto uncultured candidate phylum WOR-3 from a deep-sea hydrothermal fluid". Applied and Environmental Microbiology. 91 (7) e00188-25. Bibcode:2025ApEnM..91E.188M. doi:10.1128/aem.00188-25. PMC 12285271. PMID 40492738.
- ↑ Oren, Aharon; Göker, Markus (9 May 2023). "Candidatus List. Lists of names of prokaryotic Candidatus phyla". International Journal of Systematic and Evolutionary Microbiology. 73 (5). doi:10.1099/ijsem.0.005821. PMID 37159402.
- 1 2 3 J.P. Euzéby. "Caldifarciminota". List of Prokaryotic names with Standing in Nomenclature (LPSN). Retrieved 2026-07-16.
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