A shake flask containing a mineral growth medium with glucose was inoculated with spores of A. ochraceus and placed on a reciprocal shaker at 28° C. for 15 h. A stirred fermentor containing 5 l of medium was subsequently inoculated with 250 ml of germinated spore suspension. The used medium contained a glucose/yeast extract medium (glucose 40 g/l, yeast extract 10 g/l, pH ). The culture conditions were as follows: stirrer speed 750 rpm, airflow l/l/m, temp 28° C. Foaming was measured with an antifoam electrode and controlled by automatic addition of a silicon based antifoam agent. When the culture had a biomass concentration of at least 2 g/l a small portion of estr-4-ene-3,17-dione (1 g/l) was added to induce the synthesis of the hydroxylation enzymes. Three hours later higher concentrations of steroid were added to reach the desired concentrations as given in Table I. The steroid transformation was stopped when repeatedly no increase in conversion was observed.