Heat shock in Cronobacter sakazakii induces direct protection and cross-protection against simulated gastric fluid stress. (May 2022)

• Record Type: Journal Article
• Authors: Niu, Hongmei; MingzheYang, ; Qi, Yonghua; Liu, Yangtai; Wang, Xiang; Dong, Qingli
• Is Part Of: Food microbiology. Volume 103(2022)
• Publication Date: 2022-05
• Subjects: Cronobacter sakazakii -- Heat shock response -- Inactivation model -- Survival mechanisms; Food Microbiology -- Periodicals; Aliments -- Microbiologie -- Périodiques; Food -- Microbiology; Periodicals; Food -- Microbiology -- Periodicals; Food contamination -- Periodicals; 664.001579
• DOI: 10.1016/j.fm.2021.103948
• Languages: English
• ISSNs: 0740-0020

Abstract

Abstract: The bacterial heat shock response in foodborne pathogens is caused by exposure to higher temperatures which poses a great threat to food safety because it can undermine food processing interventions and host defense. The study assessed the heat and acid resistance of Cronobacter sakazakii following heat shock (53 °C for 15min). Inactivation curves of the heat-shocked and non-shocked C. sakazakii cells at four temperatures (56, 58, 60, and 62 °C) and simulated gastric fluid (SGF, pH 3.0) were examined and fitted with the log-linear model and the Weibull model. The inactivation parameters obtained on the basis of the Weibull model showed that heat shock significantly ( p < 0.05) increased the values of δ (time to reach 1 log reduction) and t 3d (time to reach 3 log reduction) under thermal and acid inactivation. The results proved that heat shock provided C. sakazakii direct protection from a more adverse heat challenge and cross-protection from SGF, i.e. there was a heat shock response . Results of sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) revealed that seven protein species showed enhanced expression, while four protein species showed decreased expression in the heat-shocked compared to the non-heat-shocked C. sakazakii cells. Quantitative real-time reverse transcriptase PCR (RT-qPCR) revealed upregulation of six stress related genes, ibpA, ibpB (both encoding molecular chaperons), Hsp15 (encoding heat shock protein), Hsp20 (encoding small heat-shock protein), HspQ (encoding proteases) and rpoS (encoding stationary phase sigma factor), following heat shock treatment. In addition, heat shock induced an increase proportion of saturated fatty acids (SFA), cyclic fatty acids (CFA) and the ratio of saturated fatty acids to unsaturated fatty acids (SFA/USFA), whereas reducing the proportion of unsaturated fatty acids (USFA). Consequently, establishment of inactivation models of C. sakazakii could provide data support for quantitative microbial risk assessment (QMRA). Exploration of enhanced resistance mechanisms might provide clues for prevention and control of contamination by heat-shocked C. sakazakii . Highlights: Survival curves of heat-shocked and non-shocked C. sakazakii cells could be described with the Weibull model. Heat-shock treatment greatly increased thermal resistance of C. sakazakii. Heat-shock cross-protected C. sakazakii against simulated gastric fluid (pH 3.0). Heat-shock altered the protein profile, stress-related gene expression and fatty acids composition of C. sakazakii.