Transformation of cholesterol to testosterone byMycobacterium sp.

The production of testosterone from cholesterol via a single-step microbial transformation process was investigated. A supplement of44% glucose and 1% peptone into a synthetic medium, pH control at 6.0 and continuous feeding of cholesterol were the most important parameters. Under optimal conditions, the maximum molar conversion rate of testosterone from cholesterol was up to 42.68% in 2.5-L surface-aerated fermentor after 100 h cultivation. The reduction of androst-4-ene-3.17-dione, an intermediate product, to testosterone was catalyzed by 17β-hydroxysteroid dehydrogenase inMycobacterium sp. Testosterone was isolated from the fermentation broth by the addition of Amberlite XAD-7 resin and was further purified by flash chromatography on a silica gel column. After crystallization in acetone, testosterone could be obtained as needle crystals.