Stress Response of Acid-shocked Cronobacter sakazakii against Subsequent Acidic pH, Mild Heat, and Organic Acids

Abstract

This study was conducted to determine the resistance of acid-shocked Cronobacter sakazakii to environmental stresses. C. sakazakii pre-exposed to various pH levels was treated with acid stress (pH 3.06), heat stress (55 degrees C), and organic acid stress, respectively. Overall, higher D-values were obtained in samples pre-exposed to acidic pH conditions (pH 3.06, 4.00, and 5.02) compared to a control (pH 7.20) when the samples were subsequently stressed. For 0.1 M acetic acid, the D-values of non-adapted C. sakazakii ATCC 29004 and ATCC 29544 were 19.69 and 15.49 h, respectively, whereas the D-values of acid-shocked C. sakazakii ATCC 29004 and ATCC 29544 by pre-exposure to pH 4.0 were 34.59 and 24.25 h, respectively. Acid adaptation of C. sakazakii by pre-exposure to acidic pH can enhance the resistance of cells against subsequent environmental stresses such as acidic pH, heat, and organic acids.