Because of the problem of catabolite repression, a sign)ficant class of industrially important fermentations, e.g. enzyme and antibiotic production, are controlled by the fed-batch policy in which the catabolite concentration is maintained at a low, constant, and acceptable level. An improved policy, the pulsed batch policy, is proposed which takes advantage of the sign)ficantly accelerated production rates observed when a microorganism adapts from one environment to another. Experimental and modeling results are presented for the ,BETA galactosidase from Escherichia coli case.