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Abstract

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. INTRODUCTION: Steroid biotransformation is an important microbial process for production of pharmaceutically important intermediates 1-3. Steroid biotransformation is placed amongst the important and highly valuable fermentations along with antibiotics and Vitamins. Production of 4androstene-3, 17-dione (4-AD) and androsta-1,4diene-3,17-dione (ADD) is dependent on biotransformation of easily available steroid precursors, mainly plant sterols 4-7 .

Biotransformation of Phytosterols into Androstenedione—A Technological Prospecting Study

“…Documents from the “process improvement” category addressed the increase in phytosterol bioconversion to AD by increasing steroid solubility [ 18 , 38 , 44 , 48 , 49 , 52 , 78 , 103 , 106 , 115 ], using several substances (D,L-norleucine, m-fluorophenialanine [ 106 ], ionic liquids [ 38 , 52 , 114 ], surfactants [ 40 , 78 , 103 , 112 ], and organic solvents [ 18 , 44 , 48 , 49 , 78 ]). This category also addresses the process variables involved in AD production, such as oxygenation control [ 59 ], agitation [ 23 ], temperature [ 54 , 64 , 112 ], substrate concentration [ 22 , 36 , 54 , 80 , 112 ], etc.…”

Multi-Level Optimization and Strategies in Microbial Biotransformation of Nature Products

“…Deep eutectic solvents (DESs), β -cyclodextrins derivatives (CDs), tween 80, Ionic liquids (ILs), and hydroxypropyl- β -cyclodextrin (HP- β -CD) are new classes of promising green solvents to overcome many drawbacks associated with organic solvents. In the process of the microbial transformation of steroids, they can promote the solubility of steroids, reduce product inhibition, enhance biocompatibility, and increase cell membrane permeability [ 65 , 66 , 67 , 68 , 69 , 70 ]. For example, Mucor circinelloides lusitanicus isolated from soil can introduce a 7a-hydroxyl group into substrates 1–5(5-en-3 β -ol steroids), but substrates 6–7 (cholesteriol and diosgenin) cannot be transformed because C-17 has a special side chain.…”