Bioconversion of steroids by Cochliobolus lunatus--II. 11 beta-hydroxylation of 17 alpha, 21-dihydroxypregna-1,4-diene-3,20-dione 17-acetate in dependence of the inducer structure.

The 11 beta-hydroxylase of the filamentous fungus Cochliobolus lunatus m 118 was induced with the substrate 17 alpha, 21-dihydroxypregna-1,4-diene-3,20-dione 17-acetate (11 beta-deoxyprednisolone 17-acetate) itself, substrate analogues, different pregnane compounds, sterols, intermediates of microbial sterol side-chain degradation or bile acids, together with 24 different steroids in a standardized test system. The resulting 11 beta-hydroxylation rate, leading to prednisolone 17-acetate and prednisolone, respectively, was determined and compared with the hydroxylation rate of non-induced cultures. The transformation yield strongly depended on the inducer structure.