Ralstonia is a genus of Gram-negative, aerobic bacteria in the class Betaproteobacteria. While Wikipedia focuses on R. solanacearum (a plant pathogen), the WikiBiome-relevant species are R. pickettii and R. metallidurans (now Cupriavidus metallidurans) — organisms with extreme multi-metal tolerance that appear in human gut microbiome studies, particularly in metal-exposed populations.
Metal Resistance — The CzcCBA Paradigm
R. metallidurans is the reference organism for bacterial heavy metal resistance, harboring the CzcCBA efflux system — the best-characterized multi-metal efflux pump in biology:
- CzcCBA exports cobalt, cadmium, zinc, and nickel, conferring survival in heavily contaminated environments srivastava 2016 environmental resistance microbes review.
- This efflux system is the prototype for co-selection: the same CzcCBA operon that confers metal tolerance also provides resistance to multiple antibiotics, demonstrating how environmental metal pollution drives antibiotic resistance srivastava 2016 environmental resistance microbes review.
Cadmium-Responsive Enrichment
Ralstonia abundance increases in response to cadmium exposure in animal models:
- Enriched in the gut microbiota of cadmium-exposed rats, consistent with its metal tolerance providing a selective advantage when competing organisms are inhibited by cadmium liu 2023 environmental cadmium rat microbiota metabolome liu 2023 cadmium microbiota metabolome rats.
- The enrichment pattern suggests Ralstonia as a potential biomarker of environmental metal exposure in gut microbiome profiling.
Disease Associations
- CKD: Enriched in gut microbiota of CKD patients, where uremic toxin accumulation creates a metal-dysregulated environment liu 2023 changes gut microbial community ckd.
- ASD: Altered in gut microbiota of constipated ASD children he 2023 altered gut microbiota scfa constipated asd chinese.
- Infant metal exposure: Ralstonia abundance correlates with infant serum metal levels, suggesting early-life metal exposure shapes Ralstonia colonization yan 2025 infant serum metals gut microbiota.
- PCOS: Present in vaginal microbiome of PCOS patients zheng 2024 pcos obesity vaginal microbiome phages.
- Diabetes/MI: Part of gut microbiome shifts in diabetes with myocardial infarction zhang 2026 metagenomic gut microbiome diabetes mi.
Cross-References
- cadmium — Ralstonia enrichment under cadmium exposure
- co selection — CzcCBA paradigm for metal-antibiotic co-resistance
- antimicrobial resistance — metal efflux pumps conferring cross-resistance
- chronic kidney disease — enriched in CKD gut microbiota
- environmental metal exposure — Ralstonia as biomarker of metal contamination