Ruminococcus

Several species formerly classified in Ruminococcus have been transferred to other genera following phylogenetic analyses. Five former species were transferred to Blautia in 2008. Ruminococcus gnavus is now classified as Mediterraneibacter gnavus. In 2026, Ruminococcus albus was transferred to Hominimerdicola as Hominimerdicola alba.

An early coculture study demonstrated interspecies hydrogen transfer between the bacterium then known as Ruminococcus albus and Wolinella succinogenes.

Ruminococcus bromii is considered a keystone species for the degradation of resistant starch in the human colon.

Lower relative abundances of R. callidus and R. bromii have been reported in people with inflammatory bowel disease. Lower relative abundances of sequences classified as Ruminococcus have also been reported in cohorts with Parkinson's disease and amyotrophic lateral sclerosis.

Phylogeny

Phylogenomic analyses have demonstrated that species assigned to Ruminococcus do not form a monophyletic group. The reduced tree below shows the placement in Genome Taxonomic Database (GTDB) release R11-RS232.