EFFECT OF THICKENING AGENTS ON THE PENICILLIN FERMENTATION

The effects of thickening agents (polyethylene glycol [PEG] 20000 and carboxymethylcellulose [CMC]) on the penicillin fermentation by Penici llium chrysogenum were investigated. By adding the thickening agents t o the fermentation medium, the growth form of the mold can be manipula ted. Depending on the amount of thicking agent added, the change in mo rphology is from compact smooth pellets to various intermediate forms, and finally to filamentous mycelia. It was found that better penicill in production was obtained when the mold was in small, fluffy, loose p ellets. The penicillin fermentation is not only affected by the thicke ning agents, but also the status of inoculum and agitation. Under the condition that the mold will otherwise grow in large pellets (e.g., un der a low level of spore inoculum), the enhancement in the penicillin production through addition of the thickening agents may be more signi ficant. In tank fermentation, the thickening agent was introduced in t he stage of preculture, rather than main culture. The increase in the broth viscosity caused by addition of the thickening agent resulted in a decrease in dissolved oxygen level, which could be compensated in t he case of PEG 20000.