Optimization of the 11α-hydroxylation of steroid DHEA by solvent-adapted Beauveria bassiana

To extend the use of Beauveria bassiana for commercial applications, the optimization of reaction conditions and accurate prediction of biotransformation products are necessary. This work enhances the selective hydroxylation capacity of strain ATCC 7159, resulting in a cost effective and eco-friendly process for the synthesis of valuable 11α-hydroxy steroids. Our work establishes the biochemical pathway of DHEA to hydroxylated intermediates with strain ATCC 7159, and distinguishes the optimum conditions for reactor arrangements, substrate concentration, reaction temperature, and pH. Higher substrate conversion, selectivity, and yield of desired product was achieved with “resting cells.” Addition of higher volumes of growing medium relative to reaction buffer increases the reaction rate. When a diluted amount of substrate is used, a higher yield of 11α-hydroxy steroids is achieved. Also, reactions at 26 °C with pH ranges between 6.0 and 7.0 result in the highest conversion (70%) and the higher product yield (45.8%). B. bassiana has the capacity to metabolize DHEA and similar steroids in different reaction schemes, and has a promising future as biocatalyst to be used in the production of drug metabolites.