(A) study on carbon vatabolite regulation of penicillin production using penicillium chrysogenum

Abstract

I. It has been produced that penicillin production in a batch fermentation process is affected by carbon catabolite regulation. The controlling mechanism, however, is still not clear enough if it involves catabolite inhibition or repression effect. This carbon catabolite regulation was studied for a better understanding of regulatory mechanism in penicillin production with Penicillium chrysogenum. Various carbon substrates were tested and corresponding penicillin productivities were analyzed in terms of volumetric penicillin production, specific penicillin production, and specific activity of penicillin synthesizing enzyme complex(penicillin synthetase) in mycelia. Specific activity of penicillin synthetase was greatly affected by cell age and kind of carbon substrates employed. High specific activity of penicillin synthetase was observed in a early phase of fermentation in case of more rapidly assimilated carbon substrates (glucose \& sucrose), although specific penicillin production was relatively low. However, in case of more slowly assimilated carbon substrate (lactose), the appearance of the synthetase activity was significantly delayed and the specific penicillin production increased slightly with specific synthetase activity. Furthermore, low specific penicillin production was observed when the residual glucose concentration in the broth was high, although the specific synthetase activity in mycelia remained almost constant. These findings confirm that the controlling mechanism of penicillin production by P.chrysogenum is catabolite inhibition rather catabolite repression, which has been vaguely suggested by other researchers. II. Process variables have studied for the ultimate purpose of the process optimization of semicontinous fermentation with filtration. As the medium optimization in this system, the concentration of com steep liquer and $MgSO_4$ was ltudied, and germination time for inoculum preparation was studied. As the preliminary culture of co...