Microbial conversion of bilirubin to urobilins in vitro and in vivo.
No urobilins are formed from bilirubin in germ-free rats. To isolate and investigate the strains of intestinal microorganisms responsible for this transformation, a suitable test medium was adopted. The strength of the medium and a rather high initial pH were found to be of importance. In this medium, suspensions of rat faeces and a single strain, Cl. ramosum (G62), converted bilirubin to urobilins. Cultivations of Cl. ramosum (G62) together with E. coli significantly enhanced the conversion, whereas addition of 4 other bacterial strains was without the influence. The highest in vitro formation of the urobilins was about 10% of the bilirubin present. When the 6 strains investigated in vitro were established in EXG rats, the in vivo conversion of bilirubin to urobilins was found to be about 15%, compared to 70% in CONV rats.
D000818:Animals; D001663:Bilirubin / Q000378:metabolism*; D003013:Clostridium / Q000378:metabolism*; D003470:Culture Media; D004926:Escherichia coli / Q000378:metabolism; D005856:Germ-Free Life; D066298:In Vitro Techniques; D051381:Rats; D011919:Rats, Inbred Strains / Q000382:microbiology; D014557:Urobilin / Q000096:biosynthesis*
D003470:Culture Media; D014557:Urobilin; D001663:Bilirubin