TWEEN 80 ALTERS THE PRODUCTION RATIO OF PHARMACEUTICALLY IMPORTANT STEROID INTERMEDIATES, 4-AD AND ADD DURING BIOTRANSFORMATION OF SOY STEROL BY MYCOBACTERIUM SP. NRRL B-3805

4-androstene-3, 17-dione (4-AD) and androsta-1,4-diene-3,17-dione (ADD) are pharmaceutically important steroid intermediates produced by steroid biotransformation. Non-pathogenic mutants of saprophytic Mycobacterium have been used for production of 4-AD and ADD. Being an intracellular process, the substrate entry is the rate limiting step for 4-AD and ADD production. This biotransformation is also limited by hydrophobic nature of sterol substrates. Uniform dispersion of sterol substrates in aqueous biotransformation medium is desired for efficient 4-AD and ADD production. Tween 80, a non ionic detergent is a promising agent to improve dispersion of hydrophobic substrates. In this study, besides the biotransformation, effects of tween 80 on growth, aggregation, cell wall fluidity and mycolic acid contents of Mycobacterium sp. NRRL B-3805 were estimated. Presence of 20g/L tween 80 led to 380 % increase in biomass. No toxic effect on biomass accumulation was evident at any of the tested concentrations (0.31 to 20g/l). In presence of 1.24 g/L tween 80, biotransformation was shifted towards ADD, resulting in 121 % more ADD production. The ratio of 4 – AD and ADD was changed from 12:1 (control) to 5:1. In presence of 5 g/L tween 80, ~50% reduction in mycolic acid was recorded. Presence of tween 80, significantly enhanced the biomass accumulation and altered the 4 – AD and ADD accumulation ratio by Mycobacterium sp. NRRL B-3805. Decrease in cell wall mycolic acid content could be correlated with increased ADD production.