Abstract: | Resting cell suspensions of Sepedonium ampullosporum have been used successfully in the pilot plant, transformation of 9β 10α-pregna-4, 6-dien-3, 20-dione to its 16α-hydroxy derivative. The resting cell enzyme system acted as a stable respiratory unit up to 150 hr after resuspension in water. Semicontinuous addition of substrate to the same cell suspension reduced overall conversion lime by 67%. Aeration and agitation were important factors affecting conversion rates. The hydroxylating system had a critical oxygen concentration above 90% saturation of air in water. Hydroxylase activity was inhibited by cyanide an d totally inhibited by the respiratory inhibitor antimycin A at concentrations much less that that concentration required to block normal respiration. |