Cascade Biotransformation of Phytosterol to Testosterone by Mycolicibacterium neoaurum VKM Ас-1815D and Nocardioides simplex VKM Ас-2033D Strains.

New methods for testosterone production from phytosterol were developed based on its cascade two-stage transformation by actinobacteria Mycolicibacterium neoaurum VKM Ac-1815D and Nocardioides simplex VKM Ac-2033D. Efficient oxidation of the phytosterol side chain by M. neoaurum resulted in formation of the main and side products: androst-4-en-3,20-dione (AD) and androsta-1,4-dien-3,20-dione (ADD), respectively, which were subsequently converted to testosterone by N. simplex. The latter reaction was reversible and catalyzed by the membrane-associated 17β-hydroxysteroid dehydrogenase (17β-HSD) capable of both oxidation and reduction of androstendione at C17. Addition of glucose and limited aeration were found to be the key factors providing for a shift of the 17β-HSD activity towards reduction in whole N. simplex cells. Testosterone production from phytosterol was realized using two approaches: (i) based on M. neoaurum cells inactivation after phytosterol conversion and application of the resting N. simplex biomass for androstenedione reduction and (ii) based on sequential application of the two living cultures. Under optimized conditions, the total yield of testosterone from phytosterol (10 g/L) reached 53 mol %. The results exceeded those reported so far for cascade phytosterol bioconversion to testosterone and may be used as a basis for development of new biotechnologies for production of the valuable steroid compounds, intermediates in the synthesis of modern medical preparations. [ABSTRACT FROM AUTHOR]