Failure of Cronobacter sakazakii to acquire direct and cross-protection against lethal stresses after exposure to sublethal ethanol

Abstract

Abstract Cronobacter sakazakii may encounter subinhibitory concentrations of ethanol stress over its lifecycle. Bacterial tolerance to homologous or heterologous stress agents may be altered as a result of ethanol adaptive responses. Therefore, the tolerance of ethanol-exposed and control cells to subsequent lethal stresses was evaluated in the current work. It was discovered that sublethal ethanol exposure increased the susceptibility to lethal ethanol stress in C. sakazakii as determined by the Weibull model. Furthermore, sublethal ethanol concentration exposure in C. sakazakii did not lead to any cross-tolerance against other stressors such as benzalkonium chloride (120 mg/L), heat (55 °C), cold (4 °C), simulated gastric fluid (pH 3.0), osmotic stress (sorbitol, 0.75 g/mL), and desiccation stress. Analysis of zeta potential, scanning electron microscope, and surface-enhanced Raman spectroscopy spectra revealed that cellular injury and changes in cellular chemical composition may contribute to the reduced resistance of C. sakazakii after ethanol exposure. Furthermore, sublethal ethanol exposure resulted in an elevated proportion of unsaturated fatty acids (USFA), while reducing the proportion of saturated fatty acids (SFA) and the ratio of SFA to USFA. The developed inactivation models can serve as a valuable source of data to support quantitative microbial risk assessment. Moreover, a better understanding of the response of C. sakazakii to sublethal ethanol exposure may provide valuable insights into the prevention and control of C. sakazakii.