(265e) Optimization of Valuable Intermediates By 11-Alpha-Hydroxylation of Steroid DHEA By Solvent-Enhanced Beauveria Bassiana

Authors: 
González, R., University of Iowa
Peeples, T. L., University of Iowa

This research evaluates the oxidative capacity of fungus Beauveria bassiana; a versatile whole-cell biocatalyst used in the biotransformation of chemicals. The goal of this research is to standardize, control and optimize the biocatalysis capacity of B. bassiana in the biotransformation of DHEA. To extend use of B. bassiana to 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 metabolic pathway of DHEA and defines the optimum reactor arrangement, substrate concentration, reaction temperature and pH. NMR and LC-MS analysis were performed to characterize reaction products. Higher substrate conversion, selectivity and yield of desired product was achieved in a “Resting Cells” arrangement. As well, higher volumes of growing medium compared to reaction buffer, increase the activity of the biocatalyst. The apparent rate of reaction fits a Michaelis-Menten kinetics model with a maximum reaction rate of 4.45mM-day. Interestingly, 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 resulted 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 set-ups and has a promising future as biocatalyst to be used in the production of drug metabolites.