Table 2.

Sulfidogenic and 7a-dehydroxylating organisms, substrates, and end products.

Group	Genotoxic/tumor promoting end product	Substrate	Example organism
Sulfate reducing bacteria	H2S	Inorganic sulfate Diet Organic sulfate Organosulfates Sulfomucins Sulfated bile acids Estrogen-3-sulfates	Desulfovibrio spp
Taurine respiring bacteria	H2s	Phenylsulfates Dietary Taurine Taurine conjugated bile acids	Bilophila wadsworthia
Cysteine fermenting bacteria	H2s	Dietary Cysteine Organosul fates Assimilatory sulfite reduction	Fusobacterium nucleatum
7a-dehydroxylating bacteria	Deoxycholic acid	Taurocholic acid Cholic acid	Clostridium scindens