Objective: Permeability of hydrophobic steroid substrates across cell membrane is a critical factor during microbial bioconversion. To increase substrate intake, the feasibility of some organic solvents and emulsifiers as a substrate carrier on the bioconversion of 6-methylene androstenedione (6-MeAD) to exemestane was assessed.Methods: AD, a commonly available steroid precursor, was chemically converted 6-MeAD. The time course of exemestane accumulation was estimated after addition of 6-MeAD dissolved in some organic solvents or dispersed with emulsifiers by growing and immobilized cells of Arthrobacter simplex NCIM 2449 in shake flask cultures. Results Conclusion:The use of substrate carriers for addition of 6-MeAD increased the permeability of substrate and may be used to increase the yield of exemestane and reduce incubation time.

Objective: The present study was aimed at developing a rapid, cost effective and accurate method for quantification of exemestane using thin layer chromatography (TLC) separation followed by image analysis and to test it for monitoring the accumulation of exemestane during microbial bioconversion. Methods:After microbial bioconversion and TLC separation of products formed, exemestane was quantified using ImageQuant TL v2003 image analysis software and the results were compared with high performance liquid chromatography (HPLC) analysis. Results:The percentage error between TLC and HPLC analyses was ranged from (-) 5.18 to (+) 5.51. Bacterial strains Arthrobacter simplex IAM 1660, Nocardia sp. MTCC 1534, Pseudomonas putida MTCC 1194 and Rhodococcus rhodochorus MTCC 291 respectively yielded 79.7 (72 h), 63.9 (72 h), 69.8 (96 h) and 83.2 (96 h) mole percent bioconversion of 6-methylene androstenedione to exemestane. Conclusion:Rhodococcus rhodochorus MTCC 291 was found to be the most suitable organism for the bioconversion and may be used to develop an eco-friendly route to replace chemical synthesis that eliminates the use of toxic chemicals and side products.