Effect of nisin against Clostridium botulinum during spore-to-cell transformation.

摘要

Effects of nisin on vegetative cells and spores of Clostridium botulinum ATCC 25763 were investigated. Nisin was added at various stages of spore-to-vegetative cell transition and changes in sensitivity to the bacteriocin were observed. Different nisin preparations (Nisaplin or pure nisin) were compared for their activity against different stages of spore transformation of C. botulinum. Germination was measured by determining loss of heat resistance and observing phase darkening of spores under phase-contrast microscopy. Nisin acted bactericidally against vegetative cells and sporostatically against spores at the same concn. The bactericidal and sporostatic action of nisin was concn. dependent. Presence of nisin during spore activation by heating increased subsequent phase darkening and germination rates. However, nisin inhibited germination and outgrowth when added after the heat activation stage. Results suggest that the time of nisin addition is very important for effective control of spores when foods are heated. In addition, it may be possible to apply nisin at a stage of heating that coincides with the most sensitive stage of spore transformation.