Type-species-anchored Selenomonas reconstruction with seven crescent-to-kidney bodies; two show limited concave-surface filament context. This genus plate is representative, variable, non-diagnostic, and not a micrograph.
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- Subject
- Selenomonastaxon · genus
- Identifiers
- NCBITaxon:970
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- Scientific basis
- Selenomonas — NCBI TaxonomySelenomonas — LPSNSelenomonas sputigena type strain — BacDiveSelenomonas morphology study
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- CC BY-SA 4.0Created
A genus of Gram-negative, crescent-shaped, strictly anaerobic bacteria found in both the oral cavity and the gastrointestinal tract.
Selenomonas species are characterized by their distinctive morphology—a curved rod with a tuft of flagella arising from the concave side—and their metabolic versatility, producing propionate and hydrogen sulfide (H2S) among other metabolites.
The genus occupies an unusual ecological position: it appears as a commensal in healthy gut and oral ecosystems but is consistently enriched in several disease states, suggesting context-dependent pathogenic behavior that may be driven by altered metal and metabolite environments.
Evidence map9 cited passagesInspect provenance +
Selenomonas is a normal resident of the human oral cavity, particularly in subgingival plaque. In schizophrenia, oral Selenomonas is among the H2S-producing bacteria enriched in patients with first-episode psychosis, correlating with neuroinflammation markers including CRP, IFN-gamma, TNF-alpha, IL-8, IL-1beta, and S100B (, cross-sectional). H2S can bind iro
In the gut, Selenomonas participates in saccharolytic fermentation. In a synbiotic intervention trial for chronic kidney disease (CKD stages IIIb-IV), Selenomonas unexpectedly increased with synbiotic treatment alongside the intended restoration of lachnospiraceae (, randomized-controlled-trial, n=50). This suggests Selenomonas may benefit from the saccharol
Selenomonas is consistently enriched in proximal (right-sided) colorectal tumors, distinguishing them from distal tumors where Fusobacterium and Escherichia-Shigella predominate (, cross-sectional, n=61). This anatomical specificity suggests Selenomonas colonization is influenced by the distinct metabolic and oxygen gradients of the proximal colon.
Colorectal cancer—Enriched specifically in proximal tumors; part of the "driver-passenger" model of CRC microbial ecology (, cross-sectional)
Schizophrenia—Enriched in first-episode psychosis oral microbiome as an H2S-producing bacterium; correlates with neuroinflammation (, cross-sectional)
Chronic kidney disease—Increased with synbiotic treatment, suggesting a role in saccharolytic fermentation (, RCT, n=50)
(cross-sectional, n=208)—Identifies Selenomonas among H2S-producing bacteria enriched in first-episode schizophrenia; correlates with neuroinflammation markers.
(cross-sectional, n=61)—Maps Selenomonas enrichment in proximal CRC tumors with PCA separation from distal tumors.
(RCT, n=50)—Documents unexpected Selenomonas enrichment during synbiotic-mediated metabolic shift in CKD.
Contents
1. Metal Dependencies2. Key Enzymes and Virulence Factors3. Ecological Role4. Conditions Associated5. Key Studies6. Cross-ReferencesMetal Dependencies#
Selenomonas species require Iron for their anaerobic metabolic machinery, including iron-sulfur cluster-dependent enzymes involved in propionate production. The genus is poorly characterized at the metallomic level compared to major pathogens—an important knowledge gap given its consistent appearance in disease-associated microbiome signatures.
Key Enzymes and Virulence Factors#
Propionate production enzymes—Selenomonas contributes to the succinate/propionate pathway, producing Propionic Acid as a major fermentation end product. H2S-producing enzymes—Generation of hydrogen sulfide, a gasotransmitter that at high concentrations damages colonocytes and binds metal cofactors in host enzymes.
Flagellar motility—Unusual lateral flagellation pattern enables movement through viscous mucosal environments.
Ecological Role#
In the Oral Cavity#
Selenomonas is a normal resident of the human oral cavity, particularly in subgingival plaque. In schizophrenia, oral Selenomonas is among the H2S-producing bacteria enriched in patients with first-episode psychosis, correlating with neuroinflammation markers including CRP, IFN-gamma, TNF-alpha, IL-8, IL-1beta, and S100B (,[1]Qing 2021 -- Salivary microbiome profiling reveals a dysbiotic schizophrenia-associated microbiotaYing Qing, Lihua Xu, Ganqing Cui et al. · 2021Open reference 1 ↓ cross-sectional).
H2S can bind Iron, Copper, and Zinc in metalloenzymes, potentially contributing to Mis-Metallation—a mechanism that links oral microbial metabolites to systemic metal homeostasis disruption.
In the Gut#
In the gut, Selenomonas participates in saccharolytic fermentation. In a synbiotic intervention trial for chronic kidney disease (CKD stages IIIb-IV), Selenomonas unexpectedly increased with synbiotic treatment alongside the intended restoration of Lachnospiraceae (,[2]Vacca et al. 2023 — Synbiotic Intervention in CKD Stage IIIb-IVVacca, Calabrese, Nesti et al. · 2023Open reference 2 ↓ randomized-controlled-trial, n=50).
This suggests Selenomonas may benefit from the saccharolytic environment created by prebiotic supplementation (FOS + inulin).
In Colorectal Cancer#
Selenomonas is consistently enriched in proximal (right-sided) colorectal tumors, distinguishing them from distal tumors where Fusobacterium and Escherichia-Shigella predominate (,[3]Microbiota disbiosis is associated with colorectal cancerZhiguang Gao, Bomin Guo, Renyuan Gao et al. · 2015Open reference 3 ↓ cross-sectional, n=61). This anatomical specificity suggests Selenomonas colonization is influenced by the distinct metabolic and oxygen gradients of the proximal colon.
Conditions Associated#
Colorectal cancer—Enriched specifically in proximal tumors; part of the "driver-passenger" model of CRC microbial ecology (,[3]Microbiota disbiosis is associated with colorectal cancerZhiguang Gao, Bomin Guo, Renyuan Gao et al. · 2015Open reference 3 ↓ cross-sectional).
Schizophrenia—Enriched in first-episode psychosis oral microbiome as an H2S-producing bacterium; correlates with neuroinflammation (,[1]Qing 2021 -- Salivary microbiome profiling reveals a dysbiotic schizophrenia-associated microbiotaYing Qing, Lihua Xu, Ganqing Cui et al. · 2021Open reference 1 ↓ cross-sectional). Chronic kidney disease—Increased with synbiotic treatment, suggesting a role in saccharolytic fermentation (,[2]Vacca et al. 2023 — Synbiotic Intervention in CKD Stage IIIb-IVVacca, Calabrese, Nesti et al. · 2023Open reference 2 ↓ RCT, n=50).
Key Studies#
[1]Qing 2021 -- Salivary microbiome profiling reveals a dysbiotic schizophrenia-associated microbiotaYing Qing, Lihua Xu, Ganqing Cui et al. · 2021Open reference 1 ↓ (cross-sectional, n=208)—Identifies Selenomonas among H2S-producing bacteria enriched in first-episode schizophrenia; correlates with neuroinflammation markers.[3]Microbiota disbiosis is associated with colorectal cancerZhiguang Gao, Bomin Guo, Renyuan Gao et al. · 2015Open reference 3 ↓ (cross-sectional, n=61)—Maps Selenomonas enrichment in proximal CRC tumors with PCA separation from distal tumors.
[2]Vacca et al. 2023 — Synbiotic Intervention in CKD Stage IIIb-IVVacca, Calabrese, Nesti et al. · 2023Open reference 2 ↓ (RCT, n=50)—Documents unexpected Selenomonas enrichment during synbiotic-mediated metabolic shift in CKD.
Cross-References#
- Colorectal Cancer—Proximal tumor enrichment in CRC
- Schizophrenia—Oral H2S-producing enrichment in first-episode psychosis
- Oral Microbiome—Native oral habitat; disease-associated enrichment patterns
- Propionic Acid—Major fermentation end product
- Dysbiosis—Context-dependent enrichment across multiple disease states
- Gut-Brain Axis—H2S production as potential mediator of neuroinflammation
References 7
Numbered by first appearance in the article, then reconciled with its declared source list.
- 1
Ying Qing, Lihua Xu, Ganqing Cui et al. (2021). Qing 2021 -- Salivary microbiome profiling reveals a dysbiotic schizophrenia-associated microbiota. npj Schizophrenia.
- 2
Vacca, Calabrese, Nesti et al. (2023). Vacca et al. 2023 — Synbiotic Intervention in CKD Stage IIIb-IV. Frontiers in Nutrition.
- 3
Zhiguang Gao, Bomin Guo, Renyuan Gao et al. (2015). Microbiota disbiosis is associated with colorectal cancer. Frontiers in Microbiology.
- 4
Gong W, Jin G, Bao Y et al. (2025). Characteristics and potential diagnostic value of gut microbiota in ovarian tumor patients. Scientific Reports.
- 5
Choi S, Chung J, Cho ML et al. (2021). Analysis of Changes in Microbiome Compositions Related to the Prognosis of Colorectal Cancer Patients Based on Tissue-Derived 16S rRNA Sequences. Journal of Translational Medicine.
- 6
Liang T, Liu F, Liu L et al. (2021). Effects of Helicobacter pylori Infection on the Oral Microbiota of Reflux Esophagitis Patients. Frontiers in Cellular and Infection Microbiology.
- 7
Jessica Roelands, Peter J. K. Kuppen, Eiman I. Ahmed et al. (2023). An integrated tumor, immune and microbiome atlas of colon cancer. Nature Medicine.
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