Ligilactobacillus ruminis

Ligilactobacillus ruminis is a species of Gram-positive, homofermentative, rod-shaped lactic acid bacteria in the genus Ligilactobacillus. First described from bovine rumen contents in 1973, it has since been identified in the gastrointestinal tracts of humans and other mammals.

Taxonomy

Originally classified as Lactobacillus ruminis, the species was reclassified to the genus Ligilactobacillus following a major taxonomic revision in 2020 that split the large polyphyletic genus Lactobacillus into multiple genera based on whole-genome phylogeny.

Morphology and physiology

Ligilactobacillus ruminis cells are rod-shaped and typically range from 2 to 4 μm in length. Most strains isolated from animals are motile due to the presence of peritrichous flagella, whereas human-derived strains are often non-motile.
The species is strictly anaerobic and ferments sugars primarily to lactic acid. Its genome encodes stress resistance mechanisms and possible probiotic traits, including bile salt hydrolase and bacteriocin production.

Ecology

Ligilactobacillus ruminis is a natural inhabitant of the gut microbiota of several mammalian hosts, including cattle, pigs, horses, and humans. Studies have shown host-associated phylogenetic clustering, with some strains more adapted to particular hosts.

Probiotic potential

Ligilactobacillus ruminis has attracted attention for potential use as a probiotic due to its ability to colonize the gut, produce lactic acid, resist bile and acid, and stimulate host immunity. Motility and flagellin expression may also confer competitive advantages in the intestinal environment.