Enhancement of enterohemorrhagic Escherichia�coli O157:H7 stress tolerance via pre-heating

Abstract

Abstract. Enterohemorrhagic Escherichia coli O157:H7 infection causes several hundred cases of food poisoning every year in Japan. In severe cases, this type of food poisoning can be fatal. In the present study, we examined the induction of HSP70 in E. coli O157:H7 cells at various temperatures and the thermotolerance of E. coli O157:H7 cells alone and in contaminated food following pre-heating. We evaluated the possibility that thermotolerance by E. coli O157:H7 increases the likelihood of food poisoning. E. coli O157:H7 cells were heated at 43-51˚C, and the survival rate was examined. The temperature of highest induction of HSP70 was used as the pre-heating temperature. We measured the thermotolerance of E. coli O157:H7 cells following pre-heating as the survival after heating at 53˚C (lethal temperature). Additionally, we evaluated the thermotolerance of E. coli O157:H7 cells in ground beef following pre-heating. Heating at 47˚C for 30 min caused the highest induction of HSP70 and this temperature was selected as the pre-heating temperature. The survival rate was significantly higher for 0-90 min compared to that in cultures incubated at 53˚C without pre-heating indicating thermotolerance. Additionally, in ground beef, thermotolerance in E. coli O157:H7 cells was induced by pre-heating. We showed that E. coli O157:H7 cells acquired thermotolerance after pre-heating, which significantly increased survival after a lethal temperature, and increased the likelihood of food poisoning.

Study on Some Enteropathogens of Street Vended Meat Meals

“…The recorded data in Table (5 Heating food at high temperature 51ºC decrease the survival of E. coli cells after 10 min. and no colonies were observed after heating for 180 minute, viable E. coli were not found after at 53 ºC for 60 min (Nakano et al, 2012).…”