Penicillium camemberti AM83 strain is able to carry out effective Baeyer-Villiger type oxidation of DHEA, pregnenolone, androstenedione and progesterone to testololactone. Pregnenolone and DHEA underwent oxidation to testololactone via two routes: through 4-en-3-ketones (progesterone and/or androstenedione respectively) or through 3beta-hydroxy-17a-oxa-d-homo-androst-5-en-17-one. Analysis of transformation progress of studied substrates as function of time indicates that the 17beta-side chain cleavage and oxidation of 17-ketones to d-lactones are catalyzed by two different, substrate-induced, BVMOs. In the presence of a C-21 substrate (pregnenolone or progesterone) induction of the enzyme catalyzing cleavage at 17beta-acetyl chain was observed, whereas DHEA and androstenedione induced activity of the BVMO responsible for the ring-D oxidation; 5-en-3beta-alcohol was a more effective inducer that the respective 4-en-3-ketone.