Influence of acid tolerance responses on survival, growth, and thermal cross-protection of Escherichia coli O157:H7 in acidified media and fruit juices.

摘要: Abstract A study was done to determine survival and growth characteristics of acid-adapted, acid-shocked, control cells Escherichia coli O157:H7 inoculated into tryptic soy broth (TSB) acidified with organic acids three commercial brands apple cider orange juice. The types behaved similarly in TSB acetic acid; however, (pH 3.9) lactic acid, acid-adapted were more tolerant than acid-shocked which, turn, cells. ability the grow after inoculation TSB, then plated on agar containing sodium chloride determined. Tolerance and, less markedly, diminished, compared pathogen showed extraordinary tolerance low pH juice held at 5 or 25°C for up 42 days. Growth occurred one brand 3.98) incubated 25°C. Regardless test parameters, there no indication that cell differed acidic environment Survival control, heated studied. Within each juice, D52°C-values considerably higher those cells, which indicates heat can be substantially enhanced by acid adaptation shock.