Elevation of the activity of rate limiting enzyme
Cephalosporium acremonium strains are used for the production of cephalosporin C. However, penicillin N, which is an intermediate product in biosynthesis of cephalosporin C, accumulates. Thus the activity of enzyme (encoded in gene cefEF) responsible for converting penicillin N limits the rate of overall pathway. Expression of cefEF was elevated through increased gene dosage, and the recombinant C. acremonium exhibited IS-fold reduction in penicillin N concentration and 15% increase in the production of cephalosporin C.