Transformation of chenodeoxycholic acid by thermophilic Geobacillus stearothermophilus

We performed a series of experiments with Geobacillus stearothermophilus , a thermophile isolated from oil‐contaminated soil in the Kuwaiti desert. The organism has a good potential for the transformation of a broad spectrum of organic molecules such as steroids, amino acids, and aromatic hydrocarbons. In the present study, we tested its potential for the transformation of a bile component, chenodeoxycholic acid (CDCA). Five transformed products, namely, cholic acid, methylcholate, methylchenodeoxycholate, 3α‐hydroxy‐7‐oxo‐5β‐cholanic acid, and 7α‐hydroxy‐3‐oxo‐5β‐cholanic acid, were the major transformation products catalyzed by G. stearothermophilus . Under aerobic conditions, no evidence of side chain degradation, ring cleavage, or dehydrogenation was found among the metabolites of CDCA. CDCA transformation by a thermophile is reported for the first time.