BIOCONVERSION OF A HYDROCORTISONE DERIVATIVE IN AN ORGANIC-AQUEOUS 2-LIQUID-PHASE SYSTEM

The Delta(1)-dehydrogenation of 6-alpha-methyl-hydrocortisone-21-aceta te in an organic-aqueous two-liquid-phase system using free Arthrobact er simplex cells was studied. Chloroform, toluene, and n-octan-1-ol we re assayed for steroid solubility and biocompatibility, the latter eme rging as the most appropriate solvent. Addition of surfactants (a comm ercial-grade lecithin, phosphatidylcholine, and phosphatidyl-ethanolam ine) led to increased initial reaction rates but did not significantly change the final conversion yields. First-order apparent kinetics was observed in a menadione-saturated system for global substrate concent rations under 10 mM. Maintenance stability was considerably increased when the temperature was lowered from 30 to 25 degrees C. However, ope rational stability levels were unsufficient for biocatalyst reuse in t he rested reactional conditions.