Formation of hyodeoxycholic acid from muricholic acid and hyocholic acid by an unidentified gram-positive rod termed HDCA-1 isolated from rat intestinal microflora

A gram-positive rod bacterium, called HDCA-1, that does not belong to a known genomic species, was isolated from the rat intestinal microflora. It is able to convert the 3alpha,6beta,7beta-trihydroxy bile acid beta-muricholic acid into hydodeoxycholic acid by dehydroxylation of the 7beta-hydroxy group and epimerization of the 6beta-hydroxy group into a 6alpha-hydroxy group. The strain HDCA-1 could not be grown unless a nonconjugated 7-hydroxylated bile acid and an unidentified growth factor produced by a Ruminucoccus productus strain that was also isolated from the intestinal microflora were added to the culture medium.