Some Effects of Preservatives on the Development of Bacterial Spores

Abstract

Summary The effects of preservatives on the development of spores of Bacillus subtilis have been examined using 2 indices of development sensitive to preservatives, namely, the swelling of spores prior to vegetative cell emergence and o.d. changes of spore suspensions during germination and outgrowth. The preservatives used fall into two categories: (1) inhibitors of germination (chlorocresol and mixed esters of p ‐hydroxybenzoic acid), and (2) inhibitors of postgerminative development (cetrimide, aminacrine and phenylmercuric nitrate). None of the preservatives prevented the initial phase of spore swelling and it is suggested that this is attributable to a nonmetabolic (inanimate) hydration. The inhibition of germination by a category 1 preservative (chlorocresol) is readily reversible by washing and to prevent germination the preservative must be added early in the process. The inhibition of postgerminative development by a category 2 preservative (aminacrine) cannot be reversed by washing treated spores.