Table 1|.
Bacterial taxa contributing to bile acid metabolism in the human colon
| Enzymatic | Bacterial taxon | Substrate | Product | Refs. |
|---|---|---|---|---|
| Bile salt hydrolase or conjugase | Clostridia, Bacteroides, Enterococcuc. Bifidobacteria, Lactobacilli, methanogenic archaea | Conjugated bile acide or free bile acids | Unconjugated bile acide, MCBAs | 66–72 |
| C3-oxidation or epimerization (iso-pathway) | Ruminococcus spp., Eggerthella lenta, Baccillus coagulans, Clostridium inoculum, Lachnospira pectinoschiza, Peptoniphilus harei, Catenibacterium. Lactobacillus, Aldercreutzia equolifaciens, Dorea formicigenerans, Blautia hydrogenotrophica | CA, CDCA, DCA, LCA | 3-OxoCA, isoCA, 3-oxoCDCA, isoCDCA, 3-oxoDCA, isoDCA, 3-oxoLCA, isoLCA | 169 |
| C7-oxidation or epimerization (urso-pathway) | Escherichia coli, Clostridium sardiniense, Ruminococcus gnavus. Ruminococcus torques, Collinsella aerofaciens, Clostridium scindens, Bacteroides spp. | CDCA, CA | UDCA (from CDCA), UCA (from CA) | 205 |
| C12-oxidation or epimerization (epi-pathway) | C. scindens, Clostridium hytemonae, Peptacetobacter hiranonis, Clostridium leptum, Holdemania filiformis, Anaerostipes hadrus. Coprococcus comes. Bacteroides pectinophilus, Methanobrevibacter, Methanosphaera. Dorea sp., Clostridium paraputrificum, Eisenbergiella. Olsenella, Collinsella spp., Ruminococcus lactaris. E. lenta | CA, DCA | 12-OxoCDCA, 12-oxoLCA, epiCA, epiDCA (lagoDCA) | 169,181,182 |
| C7-dehydroxylation (Hylemon-Bjorkhem pathway) | C. scindens, C. hylemonae, P. hiranonis, Extibacter muris, Dorea sp., Proteocatella sphenisci, Faecalicatena contorta, C. leptum, Clostridium sordellii | CDCA, UDCA, CA | DCA, LCA | 37,129,136,143,206,207,214 |
| Bile acid fatty acid-conjugating enzymes | Unknown (mixed faecal bacteria) | 118 | ||
| Bile acid sulfatase | Clostridium spp., Pseudomonas aeruginosa | 3-Sulfo bile acids (for example, 3-sulfoCA) | Unconjugated bile acids (for example, CA) | 102,208,209 |
| C3-dehydroxylation | Clostridium sporogenes, Clostridium perfringens, C. paraputrificum, Clostridium sordellii | 3-SulfoLCA | 5β-cholanic acid, Δ3-cholenic acid, isoLCA | 157 |
| C12-dehydroxylation | Bacteroides spp., R. gnavus | CA, DCA | CDCA from CA, LCA from DCA | 168,169 |
| Allo-secondary bile acid pathways | C. scindens, C. hylemonae, Parabacteroides spp., Bacteroides spp., Holdmania hathewayi, Odoribacter sp., Alistipes spp. | DCA, LCA, isoDCA, isoLCA | alloDCA, alloLCA, isoDCA, isoLCA | 57,59 |
CA, cholic acid; CDCA, chenodeoxycholic acid; DCA, deoxycholic acid; LCA, lithocholic acid; MCBAs, microbially conjugated bile acids; UDCA, ursodeoxycholic acid.