Onset of new catalytic activity in immobilized spores of Aspergillus ochraceus TS due to in situ germination: C17-C20 lysis accompanies 11 alpha-hydroxylation of steroid.

The change in product pattern during transformation of progesterone by calcium alginate entrapped spores of Aspergillus ochraceus TS (A. ochraceus TS) due to germination in situ is reported. While progesterone was transformed exclusively to its 11 alpha-hydroxy derivative by both free and immobilized spores of A. ochraceus TS, the latter germinated in situ by yeast extract furnished 11 alpha-hydroxyprogesterone and C19 steroids during transformation under identical conditions. The characterization of metabolite(s) and the pathway proposed demonstrated that delta 1-dehydrogenation and lysis of C17-C20 bond are apparently two independent reactions. The change in product profile due to activation of immobilized spores is believed to be caused by accumulation of compatible solutes in the biocatalyst which had relatively low water content.