title: Assessing the microbial oxidative stress mechanism of ozone treatment through the responses of Escherichia coli mutants.
abstract: OBJECTIVE
  To investigate the effect of the oxidative stress of ozone on the microbial inactivation, cell membrane integrity and permeability and morphology changes of Escherichia coli.
  
  
  RESULTS
  Escherichia coli BW 25113 and its isogenic mutants in soxR, soxS, oxyR, rpoS and dnaK genes were treated with ozone at a concentration of 6 μg ml⁻¹ for a period up to 240 s. A significant effect of ozone exposure on microbial inactivation was observed. After ozonation, minor effects on the cell membrane integrity and permeability were observed, while scanning electron microscopy 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 that has previously been shown to protect against oxidative stress did not protect against ozone treatment in this study. Furthermore, RpoS was important for the survival against ozone.
  
  
  CONCLUSIONS
  This study provides important information about the role of oxidative stress in the responses of E. coli during ozonation.
authors: School of Food Science and Environmental Health, Dublin Institute of Technology, Dublin, Ireland.
authors: S
authors: S
authors: Patil
authors: V P
authors: VP
authors: Valdramidis
authors: K A G
authors: KA
authors: Karatzas
authors: P J
authors: PJ
authors: Cullen
authors: P
authors: P
authors: Bourke
mesh_terms: D002462:Cell Membrane / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000648:ultrastructure; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D050296:Microbial Viability / Q000187:drug effects*; D009154:Mutation; D018384:Oxidative Stress; D010126:Ozone / Q000494:pharmacology*
chemical_list: D029968:Escherichia coli Proteins; D010126:Ozone