Tushar Banerjee

Mixed Culture Bioconversion of 16-Dehydropregnenolone Acetate to Androsta-1,4-diene-3,17-dione: Optimization of Parameters

Bioconversion of 16‐dehydropregnenolone acetate (16‐DPA) to androsta‐1,4‐diene‐3,17‐dione (ADD), an intermediate for the production of female sex hormones, by mixed culture of Pseudomonas diminuta MTCC 3361 and Comamonas acidovorans MTCC 3362 is reported. Various physicochemical parameters for the bioconversion of 16‐DPA to ADD have been optimized in shake flask cultures. Nutrient broth inoculated with actively growing co‐culture proved ideal for bacterial growth and bioconversion. A temperature range of 35–40 °C was most suitable; higher or lower temperatures adversely affected the bioconversion. Dimethylformamide below 2% concentration was the most suitable carrier solvent. Maximum conversion was recorded at 0.5 mg mL−1 16‐DPA. A pH of 5.0 yielded a peak conversion of 62 mol % in 120 h incubation period. Addition of 9α‐hydroxylase inhibitors failed to prevent further breakdown of ADD to nonsteroidal products. 16‐DPA conversion in a 5 L fermenter followed a similar trend.

Bioconversion of 16-dehydropregnenolone Acetate to Exclusively 4-androstene-3,17-dione by Delftia acidovorans MTCC 3363

Delftia acidovorans MTCC 3363 was found to convert 16-dehydropregnenolone acetate (16-DPA) exclusively to 4-androstene-3, 17-dione (AD). Addition of 9α-hydroxylase inhibitors was not required for preventing the accumulation of byproducts. The effect of pH, temperature, substrate concentration, surfactants and carrier solvents on this bioconversion has been studied. 16-DPA was maximally converted in buffered medium at pH 7.0, at temperature 30°C and 0.5 mg ml-1 substrate concentration. Detergent addition and temperature above 35°C had deleterious effect on bioconversion. Dioxan was found to be the best carrier solvent for biotransformation of 16-DPA to AD.