Acid stress, starvation, and cold stress affect poststress behavior of Escherichia coli O157:H7 and nonpathogenic Escherichia coli.
The effects of acid shock, acid adaptation, starvation, and cold stress of Escherichia coli O157:H7 (ATCC 43895), an rpoS mutant (FRIK 816-3), and nonpathogenic E. coli (ATCC 25922) on poststress heat resistance and freeze-thaw resistance were investigated. Following stress, heat tolerance at 56 degrees C and freeze-thaw resistance at -20 to 21 degrees C were determined. Heat and freeze-thaw resistance of E. coli O157:H7 and nonpathogenic E. coli was enhanced after acid adaptation and starvation. Following cold stress, heat resistance of E. coli O157:H7 and nonpathogenic E. coli was decreased, while freeze-thaw resistance was increased. Heat and freeze-thaw resistance of the rpoS mutant was enhanced only after acid adaptation. Increased or decreased tolerance of acid-adapted, starved, or cold-stressed E. coli O157:H7 cells to heat or freeze-thaw processes should be considered when processing minimally processed or extended shelf-life foods.
Leenanon
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B
Department of Food Science and Technology, Southeast Dairy Foods Research Center, Mississippi State University, Mississippi State 39762-9805, USA.
Drake
M A
MA
D000222:Adaptation, Physiological; D015169:Colony Count, Microbial; D004926:Escherichia coli / Q000254:growth & development / Q000502:physiology*; D019453:Escherichia coli O157 / Q000254:growth & development / Q000502:physiology*; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D005615:Freezing; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D013217:Starvation; D013696:Temperature; D013997:Time Factors