Microbial transformations of steroids

The absolute substrate specificity was found in studying transformations of steroids by the 663 strain ofBeauveria bassiana. The presence of hydroxyl in 17α - position is critical for the direction of transformation. Pregnene steroids are above all hydroxylated in 11α-position. The 11α - derivative originated from 17α - derivatives is the main and end metabolite. Two more mutually independent reactions occur after 11α-hydroxylation of 17α-nonhydroxylated derivatives, splitting of the side chain on C₁₇ resulting in 11α - hydroxytestosterone as a main metabolite and hydroxylation in 6β -position to respective 6 β, 11 α-di-hydroxy-4-pregnene derivative. Hydroxylation in 6 β-position of androstene steroids was not found. Steroids substituted both in positions C₁₁ and C₁₇ are not transformed at all.