Low- p H Activation of Bacillus cereus Spores

Abstract

Heat activation of bacterial spores at low pH was investigated in detail. Unlike activation of spores in distilled water at a neutral pH, activation at low pH involves two superimposed processes: enhanced activation and death. Low-pH-activated spores failed to germinate in D-alanine, in contrast to spores activated at neutral pH, owing to the abolition of alanine-racemase activity. Morphological and permeability changes such as release and partial disruption of spores were dipicolinic acidobserved during low-pH activation. The kinetics pattern of low-pH activation, as well as the change in properties of the spores thereafter, suggest that the mechanism of low-pH activation differs from that of other kinds of heat-activation.

Unlocking the Sporicidal Potential of Ethanol: Induced Sporicidal Activity of Ethanol against Clostridium difficile and Bacillus Spores under Altered Physical and Chemical Conditions

“…Dormant spores are resistant to temperatures up to 80°C for over an hour [ 20 – 22 , 25 ]. To determine the effect of elevated temperature on the sporicidal efficacy of ethanol, ten microliters of spores (~10 6 CFU) were incubated in one mL of 70% ethanol or deionized water at ~22°C (room temperature), 55°C or 80°C.…”

“…Gould et al demonstrated that Bacillus cereus spores became susceptible to killing by lysozyme after exposure to reducing agents that damage the disulfide bonds in proteins [ 24 ]. Similarly, exposure to low pH has been shown to reduce the resistance of Bacillus cereus spores to sub-lethal heat treatments [ 25 ].…”