STUDIES OF A PELLETED GROWTH FORM OF RHIZOPUS NIGRICANS AS A BIOCATALYST FOR PROGESTERONE 11-ALPHA-HYDROXYLATION

The noncoagulative type of pellet formation can be induced in submerge d cultivation of the filamentous fungus Rhizopus nigricans. The size a nd constitution of the hyphal agglomerates obtained varied with change s in inoculum size and agitation speed for given media composition and cultivation conditions. The physiological state of mycelium, used for a further process of biotransformation, was estimated by following th e growth kinetics, pH value and substrate utilization during submerged cultivation. Namely, differences in pellet morphology and physiology affect the ability of R. nigricans to hydroxylate progesterone at the 11 alpha position. A repeated batch procedure revealed the best mainte nance of biotransformation capacity for pellets, obtained from the gro wth phase of cultivation at high agitation speed and with low inoculum size. (C) 1998 Elsevier Science B.V. All rights reserved.