Studies in the production of penicillin, respiration and growth of penicillium chrysogenum in submerged culture, in relation to agitation and oxygen transfer

The submerged‐culture process for the production of penicillin by Penicillium chrysogeman was investigated in the laboratory. An attempt was made to determine whether there was any rigid relationship between the growth and respiration of the mould and the yield of penicillin, and whether the rate of transfer of oxygen to the liquid phase always limited the yield of penicillin. With these objects in view fermentations were carried out with different types of fermenter, concentrations of medium and strains of the mould. The results indicated that there was no rigid relationship between the various processes. This view was supported by a study of the effect of temperature on the different reactions. With any particular set of conditions, however, changes in the speed of stirring produced effects on growth, respiration and yield of penicillin which appeared to be related. This was doubtless due to the effect of changes in agitation on parallel but relatively independent processes. Our results suggest that the yield of penicillin depends mainly on the suitability of the agitation for its particular enzyme system, and that at present improvements can best be sought by empirical means. Fermenters and fermentation‐systems will show different responses to changes in conditions depending on which part of the enzyme system producing penicillin is limiting its production.