The effect of nisin‐sodium chloride interactions on the outgrowth of Bacillus licheniformis spores

Abstract

The effect of salt (NaCl) on the efficacy of nisin in preventing outgrowth of Bacillus licheniformis spores was determined in Plate Count Agar (PCA). An equivalent liquid medium was used for heat activation. Nisin and salt were added to the heat‐activation medium, the PCA, or both. The spores were extremely sensitive to nisin; outgrowth were completely inhibited in salt‐free media when 10 iu/ml of nisin was present in both the heat‐activation and the growth media or when 100 iu/ml nisin was present in either the heat‐activation and the growth medium. In media supplemented with 1% salt, outgrowth occurred from 1% of spores exposed to 100 iu/ml nisin in either the heat‐activation or the growth medium. A 3% salt supplement was necessary before detectable outgrowth occurred when both the heat‐activation and the growth media contained 100 iu/ml nisin. Salt appears to antagonize the sporicidal action of nisin by interfering with nisin adsorption onto the spore.