Sublethal sanitizer stress and adaptive response of Escherichia coli O157 : H7

The effect of sublethal exposure to peroxyacetic acid (PAA) sanitizer on ad aptation to peroxidative stress and development of thermal cross-resistance was investigated in Escherichia coli O157:H7. Acute sublethal PAA sanitize r exposure was used to represent a contact scenario. Cultures were grown in Trypticase soy-yeast extract broth. Acute treatment cultures were pretreat ed with 0.1% PAA, then all cultures were challenged at either 80 mM H2O2 Or 54 degreesC. Acute and peroxide control cultures showed substantially incr eased peroxidative tolerance (D-80mM > 2 h) versus negative control culture s not exposed to sanitizer (D-80mM = 0.19 +/- 0.03 h). The inactivation rat e of the acetic acid control (D-80mM = 0.21 +/- 0.05 h) was similar to the negative control rate. Acute (D-54 degreesC = 0.55 +/- 0.07 h) cultures did not exhibit increased thermal resistance versus the control (D-54 degreesC = 0.54 +/- 0.07 h). Thermal injury was determined as difference in D-54 de greesC value (DeltaD(54 degreesC)) Obtained on pyruvate and deoxycholate me dia. Thermal-induced injury was not observed in either control (DeltaD(54 d egreesC) = 0.04 h) Or acute (DeltaD(54 degreesC) = 0.05 h) cultures.