Biotransformation of various natural sterols to androstenones by Mycobacterium sp. and some steroid-converting microbial strains

Abstract

The selected standard bacterial strains ( Arthrobacter citreus TISTR 820, Bacillus sphaericus ATCC 13805, Bacilllus stearothermophilus TISTR 329, Corynebacterium aquaticum TISTR 823, Pseudomonas acidovorans TISTR 356, Streptomyces peucetius TISTR 3355) and fungal strains ( Aspergillus niger TISTR 3254, Aspergillus terreus TISTR 3109, Cunninghemella elegans TISTR 3370, Curvularia lunata TISTR 3292, Penicillin siamensis TISTR 1253, Rhizopus arrhizus TISTR 3188) were screened for sterol side-chain cleavage activity using β-sitosterol as a model substrate. In various solubility conditions, the main predicted products, 4-androstene-3,17-dione (AD), 1,4-androstadiene-3,17-dione (ADD) and testosterone (TS) were not obtained in all screening species. Both of Mycobacterium sp. NRRL B-3683 and Mycobacterium sp. NRRL B-3805 were able to convert β-sitosterol to AD and ADD. The principal product from Mycobacterium sp. NRRL B-3683 was AD, meanwhile Mycobacterium sp. NRRL B-3805 was ADD. Structural feature of sterol substrates affected to androstenone production. Compared to all tested sterols, β-sitosterol was higher converted into total androstenones in yield of 75.87 and 83.86% by Mycobacterium sp. NRRL B-3683 and Mycobacterium sp. NRRL B-3805, respectively. Almost equivalent of maximum AD and ADD with total conversion of 81.83% was observed in mixed cultures of both strains.