Definition
Muribaculum is a genus of Gram‑negative, obligately anaerobic bacteria within the family Muribaculaceae (order Bacteroidales). The type species, Muribaculum intestinale, was isolated from the intestinal tract of laboratory mice.
Overview
The genus was formally described in 2016 following cultivation efforts that targeted the previously uncultured bacterial lineage designated S24‑7, a dominant component of the murine gut microbiota. Species of Muribaculum are rod‑shaped, non‑spore‑forming, and display fermentative metabolism, producing short‑chain fatty acids such as acetate and propionate from carbohydrate substrates. Phylogenetic analyses based on 16S rRNA gene sequences place Muribaculum within the phylum Bacteroidota, and comparative genomics indicate a genome size of approximately 2.4–2.6 Mbp with a GC content around 45 mol%.
Ecologically, members of this genus are considered commensal bacteria adapted to the intestinal environment of mice and other rodents. Their abundance correlates with diet composition and health status, and they have been implicated in the modulation of host immune responses, although the precise functional roles remain under investigation.
Etymology / Origin
The name Muribaculum derives from the Latin mus (mouse) and baculum (rod), reflecting its isolation from the mouse gut and its rod‑shaped morphology.
Characteristics
| Feature | Description |
|---|---|
| Cell morphology | Straight or slightly curved rods, 0.5–1.0 µm in width and 2–5 µm in length; no flagella observed. |
| Gram stain | Negative. |
| Oxygen requirement | Obligate anaerobe; growth only under strict anaerobic conditions. |
| Metabolism | Ferments a range of mono‑ and oligosaccharides; produces acetate, propionate, and succinate as major end‑products. |
| Growth media | Isolates grow on rich, anaerobic media such as brain‑heart infusion supplemented with hemin and vitamin K. |
| Genome | Single circular chromosome; ~2.5 Mbp; encodes enzymes for polysaccharide breakdown and carbohydrate transporters typical of gut Bacteroidales. |
| Ecological niche | Predominantly the gastrointestinal tract of mice; detectable in fecal samples and intestinal mucosa. |
| Clinical relevance | Not known to be pathogenic; regarded as a commensal constituent of the murine microbiome. |
Related Topics
- Muribaculaceae – The bacterial family containing Muribaculum and related genera, many of which are abundant in rodent guts.
- S24‑7 lineage – The former taxonomic placeholder for a large, uncultured clade of Bacteroidales bacteria later resolved into Muribaculaceae.
- Gut microbiota of mice – The complex community of microorganisms inhabiting the murine gastrointestinal tract, wherein Muribaculum is a prevalent member.
- Short‑chain fatty acids – Metabolic products of fermentative gut bacteria that influence host physiology.
- Anaerobic cultivation techniques – Methods employed to isolate obligate anaerobes such as Muribaculum from environmental or host samples.