Temperature, pH, and Spore Load Effects on the Ability of Nisin to Prevent the Outgrowth of Clostridium botulinum Spores

Abstract

ABSTRACTThe effectiveness of nisin in preventing the outgrowth of spores of Clostridium botulinum types A, B, and E in TPYG broth was profoundly affected by pH, temperature of heat‐shocking, length of the heat‐shocking period, and spore load. Nisin was considerably more effective at pH 6 than at either pH 7 or pH 8 in limiting the outgrowth of all six tested strains. Heat‐damaged spores were also more sensitive to nisin. Both higher heat‐shocking temperatures in the range 20‐30°C higher than the optimal heat‐shocking temperatures for the particular strain and longer heat‐shocking periods served to lower the levels of nisin required to inhibit spore outgrowth. Nisin was more effective against spore loads of 102spores/ml. than higher spore loads of 103 or 104 spores/ml with all of these variables taken into consideration, the order of sensitivity of the spores of the various strains of C. botulinum was strain 56A < strain 69A < strain 113 B = strain 213 B < strain Beluga E < strain Minnesota E