Formation of hydroxysteroid derivatives from androst-4-en-3,17-dione by the filamentous fungus Mucor racemosus

This study describes the transformation of androst-4-en-3,17-dione (I) into six different hydroxysteroid derivatives by the filamentous fungus Mucor racemosus after a 5-day incubation period. The microbial products were purified chromatographically and identified on the basis of their spectral data as 14α-hydroxyandrost-4-en-3,17-dione (II), 7α-hydroxyandrost-4-en-3,17-dione (III), 14α,17β-dihydroxyandrost-4-en-3-one (IV), 6β,14α-dihydroxyandrost-4-en-3,17-dione (V), 7β,14α,17β-trihydroxyandrost-4-en-3-one (VI), and 6β,11α,17β-trihydroxyandrost-4-en-3-one (VII). Observed modifications include hydroxylation at C-6β, C-7α, C-7β, C-11α, C-14α positions and 17-carbonyl reduction. The best fermentation condition was found to be 25 °C and pH 6 for 120 h with a substrate concentration of 1.0 g/L. In substrate concentrations above 6.0 g/L, the biotransformation was completely inhibited.