Bioconversion of Hydrocortisone to Prednisolone by Immobilized Bacterial Cells in a Two-LiquidPhase System

Bioconversion of Hydrocortisone to Prednisolone by Immobilized Bacterial Cells in a Two-LiquidPhase System

Bioconversion of Hydrocortisone to Prednisolone by Immobilized Bacterial Cells in a Two-LiquidPhase System

Abstract

Bioconversion of hydrocortisone to prednisolone by free, immobilized
and reused immobilized cells of three bacterial strains (Bacillus sphaericus ATCC
13805, Bacillus sphaericus SRP III and Arthrobacter simplex 6946) in an aqueous
and a two-liquid-phase system using di†erent organic solvents was investigated.
The experiments were carried out in a 125 cm3 shake Ñask at 27^2¡C, 220 rpm
for 96 h. The contents of prednisolone and hydrocortisone in samples taken at 0,
3, 6, 24, 48, 72, 96 and 144 h were determined by HPLC analysis. The immobilized bacterial cells showed higher prednisolone yield than the free form in an
aqueous system. In the two-phase systems, the butyl acetate to aqueous media
ratio of 1 : 30 for all three bacterial strains in immobilized forms gave the highest
prednisolone yields, at an incubation time of 144 h, of 87É6, 70É6 and 88É3%
respectively. For an n-decane to aqueous ratio of 1 : 6, moderate prednisolone
yields of 81É8, 47É9 and 71É4% were obtained with shorter incubation times of 72,
96 and 6 h respectively. For cyclohexane and other alcohols, the organisms produced low yields of prednisolone (0È30%). Single reuse of all three immobilized
bacterial cells gave a 3È20% lower yield of prednisolone than the non-reused
cells. The increase in hydrocortisone concentration decreased the prednisolone
production whereas increasing the n-decane to aqueous ratio from 1 : 6 to 1 : 3
caused no signiÐcant change in the productivity.

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