The effects of high pressure processing and slightly acidic electrolysed water on the structure of Bacillus cereus spores

The aim of this study was to investigate the effects of high pressure processing (HPP) and slightly acidic electrolysed water (SAEW) on the structure of B. cereus spores in order to understand the inactivation mechanism. The physiological response of spores was studied by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), dipicolinic acid (DPA) release, su­per-res­o­lu­tion mul­ti­pho­ton con­fo­cal mi­cro­scope (SMCM), and flow cytometry (FCM). The morphology of B. cereus spores treated with HPP-SAEW exhibited a large fraction damage, and also an incomplete exosporium. Furthermore, spores treated with HPP-SAEW had an irregular surface bumps, and even a critical distortion. Approximately 90% of DPA was released in the groups of treated by HPP-SAEW, and 80% of DPA was released in single HPP treatment groups. The SMCM and FCM results indicated that HPP-SAEW methods was not mainly depended on germination, but directly killed. The mechanism of HPP-SAEW possibly was that one of the proteins was particularly susceptible to SAEW under HPP conditions.