Comparison of prednisolone production from cortexolone by free and immobilized isolated and standard collection strains using mixed culture techniques

The bioconversion of cortexolone (Reichstein's Compound S) to hydrocortison e or hydrocortisone to prednisolone by reference and isolated fungi and bac teria were investigated, The reference strains Cunninghamella echinulata AT CC 8688a and Bacillus sphaericus ATCC 13805, and the isolates C echinulata SRP III and B sphaericus SRP III were used as free or immobilized farms in single or mixed cultures by either sequential or concomitant mixing. In sin gle cultures, immobilized fungi C echinulata ATCC 8688a and C echinulata SR P III showed less hydrocortisone yield than the free form, whereas immobili zed B sphaericus ATCC 13805 and B sphaericus SRP III gave higher prednisolo ne yield than the free form. In mixed cultures, free fungi with immobilized bacteria of both isolated and standard strains showed the highest predniso lone yield both by concomitant and sequential mixing. The highest prednisol one yield of 72.5 +/- 0.78% with a bioconversion rate of 0.76% h(-1) by seq uential mixing was obtained with free C echinulata ATCC 8688a with immobili zed B sphaericus ATCC 13805 at 96 h, whereas the free C echinulata SRP III with immobilized B sphaericus ATCC 13805 and the free C echinulata SRP III with immobilized B sphaericus SRP III gave 63.4 +/- 0.74% and 47.7 +/- 0.44 % at 120 h with bioconversion rates of 0.53 and 0.40% h(-1) respectively. F ree C echinulata SRP III with immobilized B sphaericus SRP III gave a maxim um yield of 52.8 +/- 0.82% with a bioconversion rate of 0.44% h(-1) at 120 h which was comparable to 59.2 +/- 0.44% with a bioconversion rate of 0.49% h(-1) obtained by free C echinulata ATCC 8688a with immobilized B sphaeric us ATCC 13805 using concomitant mixing. This study indicated high biotransf ormation activity of free fungal and immobilized bacterial isolates which s howed comparable steroidal productivity to the standard strains both in sin gle and mixed cultures by the concomitant mixing technique. (C) 1999 Societ y of Chemical Industry.