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Aims: To investigate the effect of the oxidative stress of ozone on microbial inactivation, cell membrane integrity, membrane permeability and morphology changes of Escherichia coli during ozone treatment.
Methods and Results: E. coli BW 25113 and its isogenic mutants in soxR, soxS, oxyR, rpoS, dnaK genes were treated with ozone at a concentration of 6 µg mL-1 for a period up to 4 min. A significant effect of ozone exposure on microbial inactivation was observed. After ozonation, minor effects on the cell membrane integrity and permeability were observed. Scanning Electron Microscopy (SEM) analysis showed slightly altered cell surface structure.
Conclusions: The results of this study suggest that cell lysis was not the major mechanism of microbial inactivation. The deletion of oxidative stress-related genes resulted in increased susceptibility of E. coli cells to ozone treatment, implying that they play an important role for protection against the radicals produced by ozone. However, DnaK which has previously been shown to protect against oxidative stress did not protect against ozone treatment in this study. Furthermore, RpoS was important for survival against ozone through as of yet unidentified mechanism.
Significance and impact of the study: This study provides important information about the role of oxidative stress related proteins in E. coli survival during ozonation
Bourke, P. et al. (2011) Assessing the Microbial Oxidative Stress of Ozone: Significant Role of the Oxidative Stress Proteins in the Survival of E. coli in Ozone Treatment. Journal of Applied Microbiology, vol.111 (1), 2011, p.136- 44.doi:10.1111/j.1365-2672.2011.05021.x DOI:10.1111/j.1365-2672.2011.05021.x
National Development Plan, Dept of Agriculture, Food & Fisheries