Selenomonad
| Selenomonad | |
|---|---|
Scientific classification  | |
| Domain: | Bacteria |
| Kingdom: | Bacillati |
| Phylum: | Bacillota |
| Class: | Negativicutes |
| Order: | Selenomonadales |
| Family: | Selenomonadaceae |
| Genus: | Selenomonas von Prowazek 1913[1] |
| Type species | |
| Selenomonas sputigena (Flügge 1886) Boskamp 1922 | |
| Species[2] | |
| Selenomonad | |
|---|---|
| Scientific classification | |
| Domain: | Bacteria |
| Kingdom: | Bacillati |
| Phylum: | Bacillota |
| Class: | Negativicutes |
| Order: | Selenomonadales |
| Family: | Selenomonadaceae |
| Genus: | Selenomonas von Prowazek 1913 (Approved Lists 1980)[3] |
| Type species | |
| Selenomonas sputigena (Flügge 1886) Boskamp 1922 (Approved Lists 1980) | |
| Species[2] | |
Selenomonas is a genus of Gram-negative, anaerobic, non-spore-forming bacteria in the family Selenomonadaceae. Cells are rod-shaped and may be curved or crescent-shaped; motile crescent-shaped forms are commonly called selenomonads.[4]
Cell envelope and classification
[edit]Although most members of the phylum Bacillota stain Gram-positive, members of the class Negativicutes possess an outer membrane and stain Gram-negative.[5] Selenomonas is classified in the family Selenomonadaceae within the order Selenomonadales.[6][2]
Etymology
[edit]The name Selenomonas combines the Ancient Greek word selḗnē (σελήνη), meaning "moon", with monas, meaning "monad". It refers to the crescent-shaped appearance of the cells and is unrelated to the chemical element selenium.[2]
History of classification
[edit]Crescent-shaped, motile microorganisms from the human mouth were recorded in early microscopy, including observations reported by Antonie van Leeuwenhoek in 1683. Morphologically similar organisms were subsequently assigned to several protozoological and bacteriological genera, and the limits of Selenomonas remained uncertain for much of the twentieth century.[7][8]
The rumen bacterium formerly known as Selenomonas ruminantium was originally named "Ancyromonas ruminantium".[9] It was transferred to Pseudoselenomonas as Pseudoselenomonas ruminantium in the reassessment of the family Selenomonadaceae.[4] Consequently, many older descriptions of rumen “selenomonads” do not concern species retained in the current circumscription of Selenomonas.
Early light-microscopic studies described conspicuous motility and flagella arising from the concave surface of crescent-shaped cells.[10][11] Electron microscopy later showed that the conspicuous motility structure in the rumen organism then called S. ruminantium consisted of bundles of bacterial flagella and documented different patterns of flagellar insertion among large and small crescent-shaped forms.[12][8] These studies helped resolve earlier proposals that some forms were protozoa and demonstrated that similar crescent-shaped morphology did not necessarily indicate close taxonomic relationship.[8]
Taxonomy and phylogeny
[edit]A phylogenetic and comparative-genomic reassessment substantially narrowed the circumscription of Selenomonas. Sixteen species or subspecies formerly assigned to the genus were transferred to Centipeda, Dongibacter, Pseudoselenomonas, Schleiferibacter, Wylensekiella, or "Candidatus Dighea".[4] Under the nomenclature followed by the List of Prokaryotic names with Standing in Nomenclature (LPSN), four species remain in Selenomonas: S. felix, S. lipolytica, S. oralis, and the type species S. sputigena.[13]
See also
[edit]References
[edit]- ↑ Von Prowazek, S. (1913). "Zur Parasitologie von Westafrika" [Parasitology of West Africa]. Zentralblatt für Bakteriologie, Parasitenkunde, Infektionskrankheiten und Hygiene, Abteilung I. 7 (1/2): 32–36.
- 1 2 3 4 Selenomonas in LPSN; Freese, H. M.; Meier-Kolthoff, J. P.; Sardà Carbasse, J.; Afolayan, A. O.; Göker, M. (29 October 2025). "TYGS and LPSN in 2025: a Global Core Biodata Resource for genome-based classification and nomenclature of prokaryotes within DSMZ Digital Diversity". Nucleic Acids Research. 53: D1–D12. doi:10.1093/nar/gkaf1110.
- ↑ von Prowazek, Stanislaus (1913). "Zur Parasitologie von Westafrika" [Parasitology of West Africa]. Zentralblatt für Bakteriologie, Parasitenkunde, Infektionskrankheiten und Hygiene, Abteilung I. 70: 32–36.
- 1 2 3 Heng, Yu Chyuan; Kittelmann, Sandra (28 May 2026). "Taxonomic reclassification and expansion of the family Selenomonadaceae". International Journal of Systematic and Evolutionary Microbiology. 76 (5) 007178. doi:10.1099/ijsem.0.007178. PMC 13218424. PMID 42207170.
- ↑ Marchandin, H.; Teyssier, C.; Campos, J.; Jean-Pierre, H.; Roger, F.; Gay, B.; Carlier, J.-P.; Jumas-Bilak, E. (2010). "Negativicoccus succinicivorans gen. nov., sp. nov., isolated from human clinical samples, emended description of the family Veillonellaceae and description of Negativicutes classis nov., Selenomonadales ord. nov. and Acidaminococcaceae fam. nov. in the bacterial phylum Firmicutes". International Journal of Systematic and Evolutionary Microbiology. 60 (6): 1271–1279. Bibcode:2010IJSEM..60.1271M. doi:10.1099/ijs.0.013102-0. PMID 19667386.
- ↑ Campbell, Chantal; Adeolu, Mobolaji; Gupta, Radhey S. (2015). "Genome-based taxonomic framework for the class Negativicutes: division of the class Negativicutes into the orders Selenomonadales emend., Acidaminococcales ord. nov. and Veillonellales ord. nov". International Journal of Systematic and Evolutionary Microbiology. 65 (Pt 9): 3203–3215. doi:10.1099/ijs.0.000347. PMID 25999592.
- ↑ Dobell, Clifford (1932). Antony van Leeuwenhoek and His "Little Animals". New York: Harcourt, Brace and Company.
- 1 2 3 Kingsley, V. V.; Hoeniger, J. F. M. (1973). "Growth, structure, and classification of Selenomonas". Bacteriological Reviews. 37 (4): 479–521. doi:10.1128/MMBR.37.4.479-521.1973. PMC 413832. PMID 4129090.
- ↑ "Species: Selenomonas ruminantium". List of Prokaryotic names with Standing in Nomenclature. Leibniz Institute DSMZ. Retrieved 29 July 2026.
- ↑ Lessel, E. F. Jr.; Breed, R. S. (1954). "Selenomonas Boskamp, 1922; a genus that includes species showing an unusual type of flagellation". Bacteriological Reviews. 18 (3): 165–169. doi:10.1128/MMBR.18.3.165-169.1954. PMC 180798. PMID 13189856.
- ↑ MacDonald, J. B.; Madlener, E. M.; Socransky, S. S. (1959). "Observations on Spirillum sputigenum and its relationship to Selenomonas species with special reference to flagellation". Journal of Bacteriology. 77 (5): 559–565. doi:10.1128/JB.77.5.559-565.1959. PMC 290421. PMID 13654218.
- ↑ Chalcroft, J. P.; Bullivant, S.; Howard, B. H. (1973). "Ultrastructural studies on Selenomonas ruminantium from the sheep rumen". Journal of General Microbiology. 79 (1): 135–146. doi:10.1099/00221287-79-1-135. PMID 4773919.
- ↑ "Genus: Selenomonas". List of Prokaryotic names with Standing in Nomenclature. Leibniz Institute DSMZ. Retrieved 29 July 2026.