Efficient Biotransformation of Phytosterols to Dehydroepiandrosterone by Mycobacterium sp.

In this study, a method for the efficient production of dehydroepiandrosterone (DHEA) from phytosterols in a vegetable oil/aqueous two-phase system by Mycobacterium sp . was developed. After the 3-hydroxyl group of phytosterols was protected, they could be converted into DHEA with high yield and productivity by Mycobacterium sp . NRRL B-3683. In a shake flask biotransformation, 15.05 g l −1 of DHEA and a DHEA yield of 85.39% (mol mol −1 ) were attained after 7 days with an initial substrate concentration of 25 g l −1 . When biotransformation was carried out in a 30-l stirred bioreactor with 25 g l −1 substrate, the DHEA concentration and yield was 16.33 g l −1 and 92.65% (mol mol −1 ) after 7 days, respectively. The results of this study suggest that inexpensive phytosterols could be utilized for the efficient production of DHEA.