Comparative Study of Penicillin Production with Vegetative and Spore Inoculum of Penicillium chrysogenum1

In commercial penicillin production the fermentation medium is usually seeded with a mycelial (vegetative) inoculum of Penicillium chrysogenum prepared by the following transfers: spores -+ germinator tank -seed tank. However, depending on the fermentation conditions, the operation in the germinator tank can be successfully eliminated. Goldschmidt and Koffler (1950) used spore-inoculated fermentations in their study of the effect of surface active agents on penicillin yields. Rolinson and Lumb (1953) reported that the effect of high aeration on lactose utilization appeared to be peculiar to fermentations inoculated with spores. Crawford et al. (1952) obtained identical yields of cephalosporin P with both spore and vegetative inoculum. Backus and Stauffer (1955) used spores inoculated directly into the fermentation medium to test their mutant strains of P. chrysogenum. However, comparison of penicillin yield and the fermentation cycle (time taken to reach the maximal yield) between fermentations inoculated directly with spores and with vegetative inoculum has not been reported for the high yielding strains of P. chrysogenum. During the early days of penicillin fermentation with very low yielding strains, Foster, Woodruff, and McDaniels (1946) observed that in spore-inoculated fermentation in aerated and agitated laboratory fermentor, maximal titre (50 u per ml) was reached at 120 hr as compared to 72 hr with vegetative inoculum. The method of direct inoculation of spores, if successful under industrial fermentation conditions, would eliminate one of the major intermediate stages in penicillin fermentation with a consequent economy in operations. To be considered equally efficient, different fermentation conditions should yield the same amount of penicillin in the same fermentation cycle. This paper reports a comparative study of penicillin production in shake flask and agitated and aerated fermentors with spores and vegetative inoculum.