Analysis of Intracellular pH in Escherichia coli O157:H7 to Determine the Effect of Chlorine Dioxide Decontamination

Abstract

The aim of this study was to investigate the response of Escherichia coli O157:H7 when exposed to different concentrations of sanitation agent chlorine dioxide (ClO2) by determining intracellular pH (pH(i)). For this purpose, fluorescence ratio imaging microscopy was used together with pH-sensitive, ratiometric green fluorescent protein that was introduced in E. coli O157:H7 cells. Along with pH(i), colony counts were determined during the treatment with ClO2. Results revealed several post-treatment subpopulations with different physiological states, as judged by their pH(i). The fraction of cells with no pH gradient increased, and the colony count decreased as the concentration of ClO2 increased.