BACTERIAL OXIDATION OF CHOLIC-ACID BY ARTHROBACTER SP

Some bacteria possess the ability to convert cholic acid (CA) to pharm acologically important chenodeoxycholic acid (CDCA) or to its precurso r 3 alpha,7 alpha-dihydroxy-12-oxo-5 beta-cholan-24-ic acid (12-oxo-CD CA). The ability of several bacterial strains to convert CA to 12-oxo- CDCA was tested in our work. The highest conversion was reached by one strain of Arthrobacter sp. which converted up to 61 % CA to 12-oxo-CD CA in a complex medium containing 4 % (W/V) CA under aerobic condition s. 12-Oxo-CDCA was further oxidized to 3,12-dioxo-7i-hydroxy-5 beta-ch olan-24-ic acid (3,12-dioxo-7-OHCA) that represented up to 10 % of tot al bile acids in the cultivation medium after a 1-d cultivation. The c oncentration of 12-oxo-CDCA increased rapidly during the first hours o f cultivation, maximal yields were achieved between 20 and 24 h of cul tivation and they decreased after that due to further bacterial oxidat ion.