Synthesis of 9 alpha-hydroxysteroids by a Rhodococcus sp

9 alpha-Hydroxylation of delta 5-3 beta-hydroxysteroids (of androstane, pregnane, 24-nor- and 21,24-bisnorcholane groups) was carried out by a Rhodococcus sp., isolated from a petroleum-containing soil sample. A large number of the investigated steroids was transformed into 9 alpha-hydroxy-delta 4-3-ketones in satisfactory yields (50-90%) at high initial concentrations of the substrates (0.5-5.0 g/L). The influence of some structural features of the steroid molecule on the progress and effectiveness of the microbial transformation was also shown.