11b-Hydroxylation of cortexolone (Reichstein’s compound S) to hydrocortisone using immobilized Cunninghamella elegans spores

Two steps bioconversion of cortexolone (Reichstein’s compound S) to its
1-dehydro-11b-hydroxy derivatives and prednisolone, was successfully performed by the use of C. elegans for the production of cortisol and prednisolone from cortexolone. The combinations of sequential reactions, 11b-hydroxylation and
1-dehydrogenation were performed by immobilized spores of Cunninghamella elegans. The immobilization technique was carried by either entrapment in sodium alginate or by adsorption on silver, 8 micron glass wool method. Maximum production of cortisol and prednisolone were obtained after 72 h transformation period using immobilized spores of C. elegans of concentration 2 x 107 spores/mL for both entrapment and adsorption. The highest transformation efficiency was recorded on using 1.6% w/v glass wool (92%) compared to that when the fungal spores were entrapped in 3% alginate (84%). Each immobilized microbial system was stable and could be used for the sequential reactions repeatedly (operational period, 18 days using entrapped C. elegans in alginate beads and 45 days using adsorbed spores on glass wool).