Pseudoselenomonas ruminantium is a species of obligately anaerobic, Gram-negative, motile bacteria in the family Selenomonadaceae. Its cells are curved or crescent-shaped rods, and it was originally isolated from the bovine rumen. The type strain is GA192, also deposited as ATCC 12561 and DSM 2150.
Taxonomy The organism was originally described as "Ancyromonas ruminantium" in 1889 and was later classified as Selenomonas ruminantium. The former species included the subspecies S. ruminantium subsp. ruminantium and S. ruminantium subsp. lactilytica.
Phylogenetic and comparative genomic analyses published in 2026 placed the type-bearing taxon in the new genus Pseudoselenomonas as Pseudoselenomonas ruminantium. The former subspecies S. ruminantium subsp. lactilytica was recognized as a separate species, Pseudoselenomonas lactilytica.
Characteristics and metabolism Strain GA192 ferments glucose and produces L-lactate but does not ferment lactate. Under glucose-limited continuous culture, it produces predominantly propionate and acetate at lower growth rates, with proportionally greater lactate production at higher growth rates.
GA192 can use arabinose, xylose, and xylo-oligosaccharides ranging from xylobiose to xylopentaose, as well as larger xylo-oligosaccharides. In coculture, the strain can consume soluble xylo-oligosaccharides released during the degradation of xylan by Butyrivibrio fibrisolvens, demonstrating metabolic cross-feeding between rumen bacteria.
A bifunctional glycoside hydrolase family 43 β-D-xylosidase/α-L-arabinofuranosidase from the species has been characterized biochemically and by X-ray crystallography.
References
External links Type strain of Pseudoselenomonas ruminantium at BacDive