Bacterial strains with altered metabolism of bile acids and their use.

Strains of bacteria characterized by exhibiting: (a) a 7O-dehydroxylase activity of less than 50%, and (b) a bile acid deconjugation activity of less than 50%, and descendants, mutants and derivatives thereof preserving activities (a) and (b); and a pharmaceutical composition comprising one or more of such strains and useful of same for preventing and treating deseases associated with or caused by an altered metabolism of bile acids.