(A) studies on the process optimization of penicillin fermentation

Abstract

Penicillin fermentation was performed in the various scale of fermentation vessels using the mutant strain of $\mbox{\underline{Penicillium}}$ $\mbox{\underline{chrysogenum}}$, originally ATCC 12690, which had been obtained by treatments of Methyl-bis (β -chloroethyl) amine and U.V. light. In this thesis, process variables have been studied for the ultimate purpose of the process optimization of penicillin fermentation. As the most important variables, sugar consumption rate, specific consumption rate of sugar, dissolved oxygen, and optimal concentration of precursor were selected, and the applicability of soybean meal and soybean flour as main nitrogen sources was evaluated. The optimal concentration of precursor and the applicability of soybean meal and soybean flour as main nitrogen sources were studied with shake-flask fermentation, and sugar consumption rate, specific consumption rate of sugar and dissolved oxygen with 20 liter fermentor. The optimal concentration of precursor was found to be 0.250.50% and both the soybean meal and soybean flour equally effective as compared with corn steep liquor in penicillin production. In batch fermentation with lactose, mean sugar consumption rate during the first 120 hours varied 0.67-1.3g lactose equivalent sugar per liter per hour, specific consumption rate of sugar for maintenance energy, 0.03-0.06g lactose equivalent sugar per g-dry weight per hour, and dissolved oxygen in the phase of penicillin production was maintained at the level of 65% saturation. In batch fermentation with sucrose feeding, specific consumption rate of sugar for maintenance energy varied 0.02-0.04g sucrose equivalent sugar per g-dry weight per hour, and oxygen supply was an important factor in this type of fermentation. In batch fermentation with glucose feeding for $p^H$ to be maintained at a level lower than 8.0, the maximum potency of pennicillin was one half of that with sucrose feeding, and twice as high as that with shake-flask fermen...