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Survival of S higa toxin‐producing E scherichia coli in broth as influenced by p H , water activity and temperature
Author(s) -
Balamurugan S.,
Ahmed R.,
Gao A.
Publication year - 2015
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/lam.12375
Subject(s) - escherichia coli , microbiology and biotechnology , shiga toxin , enterobacteriaceae , bacteria , toxin , biology , food science , chemistry , biochemistry , gene , genetics
This study examined the effects of and interactions between pH, a w and temperature on the survival of the top six non‐O157 STECs and Escherichia coli O157:H7. All variables significantly affected the survival of all STEC serotypes. However, a w bore the most significant effect, followed by temperature and then pH. Examination of the effect of the interaction between these variables revealed that the interaction between a w and temperature was the most significant followed by the interaction between pH and temperature and then a w and pH. Decrease in a w resulted in population reduction of all serotypes studied. This reduction in population was significantly increased with the increase in temperature and was further significantly enhanced with decreasing pH. Examination of the differences in the survival among the individual serotypes revealed that the response of each serotype to a w or temperature changes was significantly different, while their response to pH changes was similar. Analysis of the relative survival of individual non‐O157 STECs to O157:H7 revealed that the survival of O121 and O45 was not significantly different to O157:H7 while O103, O111, O145 and O26 showed less tolerance to the combined treatments, and their survival was significantly different from O157:H7. Significance and Impact of the Study Results of this study estimate the interaction between pH, a w and temperature on the survival of the top six non‐O157 STECs relative to Escherichia coli O157:H7 and provide important growth and no‐growth condition which will offer risk assessors a means of estimating the likelihood of these pathogens, if present, would grow in response to the interaction between the three variables assessed.