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INFLUENCE OF STARVATION, TEMPERATURE, AND pH ON CULTURABILITY OF ESCHERICHIA COLI O157:H7
Author(s) -
ZHAO LIQIANG,
MATTHEWS KARL R.
Publication year - 2000
Publication title -
journal of food safety
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 43
eISSN - 1745-4565
pISSN - 0149-6085
DOI - 10.1111/j.1745-4565.2000.tb00297.x
Subject(s) - chlorine , escherichia coli , starvation , population , biology , microbiology and biotechnology , chemistry , food science , bacteria , biochemistry , genetics , demography , organic chemistry , sociology , gene , endocrinology
In farm and food processing environments Escherichia coli O157:H7 can survive for days to months. In this study, we investigated the influence of starvation, pH (pH 4 or 7), temperature (4, 10 and 22C), and exposure to chlorine (50, 100, 150, 200 ppm) on culturability of E. coli O157:H7. The culturable cell population in PBS decreased to an undetectable level at 4C and 10C, but not at 22C during the experimental period. Cells suspended in PBS adjusted to pH 4 lost culturability more rapidly than at pH 7. Culturable cells were not detectable after exposure to chlorine, however, viable cell populations in the range of 1 – 2 log remained stable for 5 days. During loss of culturability two distinct morphological cell populations emerged; typical rod shaped and coccoid shaped cells. In this study, independent of exposure to chlorine, conditions of low temperature and low pH had the greatest influence on entry of E. coli O157:H7 into a VNC state.