Biotransformation of bile acids by pathogenic actinomycetes Nocardia otitidiscaviarum and Amycolatopsis sp. strains.

Three sterol-type compounds (compounds 4, 5 and 6) were isolated from culture broth of pathogenic Nocardia otitidiscaviarum IFM 0988 and Amycolatopsis sp. IFM 0703 strains which were isolated from Japanese patients. The structures of the compounds were determined by NMR and mass spectrometric analyses. The structural studies indicated that compound 4 is a biotransformation product from cholic acid derivative in a nutrient culture medium constituent by a reductase-type enzyme, and the remaining two compounds 5 and 6 are also biotransformation ones by oxidase-type enzymes.