Definition
Erysipelotrichia is a class of bacteria within the phylum Firmicutes (also referred to as Bacillota). Members of this class are Gram‑positive, predominantly anaerobic microorganisms that are commonly found in the gastrointestinal tracts of animals, including humans.
Overview
The class Erysipelotrichia comprises several orders, the most prominent being Erysipelotrichales. Taxonomically, the class includes families such as Erysipelotrichaceae and Coprobacillaceae. Species within this class have been isolated from a range of habitats, from the intestinal microbiota of mammals to environmental samples such as soil and water. Research has linked certain Erysipelotrichia members to alterations in host metabolism, immune modulation, and, in some cases, disease states such as inflammatory bowel disease and obesity, although causal relationships remain under investigation.
Etymology / Origin
The name Erysipelotrichia derives from the genus Erysipelothrix, itself named after “erysipelas,” a bacterial skin infection historically caused by Erysipelothrix rhusiopathiae. The suffix “‑trichia” is rooted in the Greek “trichos,” meaning “hair,” a reference historically used in bacterial nomenclature to denote filamentous or thread‑like morphology observed in early microscopy.
Characteristics
| Feature | Description |
|---|---|
| Cell wall | Thick peptidoglycan layer characteristic of Gram‑positive bacteria; lacks an outer membrane. |
| Morphology | Typically rod‑shaped (bacilli); some species exhibit short chains or occasional filamentous extensions. |
| Oxygen requirement | Predominantly obligate or facultative anaerobes; few are aerotolerant. |
| Metabolism | Fermentative metabolism with production of short‑chain fatty acids (e.g., acetate, butyrate) from carbohydrate substrates. |
| Genomic traits | Genomes range from 2.0 to 3.5 Mbp; contain genes for carbohydrate‐active enzymes (CAZymes) facilitating polysaccharide degradation. |
| Ecology | Core components of mammalian gut microbiota; also identified in animal skin, oral cavities, and environmental niches. |
| Clinical relevance | Certain taxa have been implicated in dysbiosis‑associated conditions; Erysipelothrix rhusiopathiae—though not a member of this class—is a known zoonotic pathogen causing erysipelas. |
Related Topics
- Firmicutes (Bacillota) – The broader phylum encompassing Erysipelotrichia and other Gram‑positive bacteria.
- Gut microbiome – The complex community of microorganisms in the gastrointestinal tract, of which Erysipelotrichia are a constituent.
- Erysipelothrix rhusiopathiae – A related genus historically associated with the name but classified in a different taxonomic group (class Erysipelotrichia is separate).
- Short‑chain fatty acids – Metabolic products of many Erysipelotrichia species that influence host energy balance and immune function.
- Dysbiosis – Imbalance in microbial communities; alterations in Erysipelotrichia abundance have been observed in several dysbiosis studies.
Note: While substantial research exists on the ecological and physiological roles of Erysipelotrichia, specific pathogenic mechanisms for most members remain under active investigation.