Lactobacillus murinus - mucosal-immunology-lab/bacterial-database GitHub Wiki
| Bacterial Information | Value |
|---|---|
| Taxonomy level | Species |
| NCBI Taxonomy ID | 1622 |
| Phylum | Firmicutes |
| Family | Lactobacillaceae |
| Genus | Lactobacillus |
| Gram stain | Gram-positive |
| Oxygen requirements | Aerotolerant anaerobic or microaerophilic |
| Spore-forming | No |
| Motile | No |
| Image |  |
L. murinus strains are non-motile rods which slowly ferment ribose and arabinose. L-lactate dehydrogenase (L-LDH) is activated by fructose-1,6-diphosphate (FDP) and Mn2+(Zheng 2020). They do not hydrolyse urea and Hippurate; they decarboxylate malate. Riboflavin is a required growth factor (Hemme 1980).
The genome size of the type-strain is 2.20 Mbp. The G+C content of DNA is 40.1 mol%.
Downregulates IL-8 production, improves gut barrier, and lowers inflammation.
In a model of caloric restriction, L. murinus was identified as more likely to be enriched in mice with a normal feeding rhythm, and simultaneously, the mice exhibited a better metabolic status than those who ate during the day (abnormal feeding rhythm)(Zhang 2021). The most abundant OTU was isolated from mouse faeces and was found to downregulate IL-8 production in TNFα-stimulated Caco-2 colonic epithelial cells (Zhang 2021).
Interestingly, they also significantly increased the lifespan and brood size of the nematode Caenorhabditis elegans. In gnotobiotic mice colonised with the gut microbiome from old mice, L. murinus decreased the intestinal permeability and serum endotoxin load, which consequently attenuated the inflammation induced by the old microbiota (Zhang 2021). Overall, L. murinus contributed to the protection of the gut barrier and the attenuation of chronic systemic inflammation.
Intranasal administration can increase lung Th17 cells and RORγt+ T regulatory cells.
In a murine model of Mycobacterium tuberculosis infection, intranasal (but not intragastric) administration of L. murinus (strain CNCM I-5314) increased the presence of lung Th17 cells and of a regulator T cells (Treg) subset known as RORγt+ Tregs (Bernard-Raichon 2021). In particular, L. murinus increased the expansion of these lung leukocytes, suggesting a local rather than systemic effect. Resident Th17 and RORγt+ Tregs display an immunosuppressive phenotype that is accentuated by L. murinus. Despite the well-known ability of M. tuberculosis to module lung immunity, the immunomodulatory effect of L. murinus was dominant, as both Th17 and RORγt+ Tregs cells were still highly increased in the lung at 42 days post-infection. Importantly, L. murinus resulted in reduction of pulmonary inflammation without increasing M. tuberculosis burden (Bernard-Raichon 2021).