Effect of Desiccation on Tolerance of<i>Salmonella enterica</i>to Multiple Stresses

<jats:title>ABSTRACT</jats:title><jats:p>Reducing the available water in food is a long-established method for controlling bacterial growth in the food industry. Nevertheless, food-borne outbreaks of salmonellosis due to consumption of dry foods have been continuously reported. Previous studies showed that dried<jats:italic>Salmonella</jats:italic>cells acquire high tolerance to heat and ethanol. In order to examine if dehydration also induces tolerance to other stressors, dried<jats:italic>Salmonella enterica</jats:italic>serotype Typhimurium cells were exposed to multiple stresses, and their viability was assessed. Indeed, desiccated<jats:italic>S</jats:italic>. Typhimurium acquired higher tolerance to multiple stressors than nondesiccated cells. The dried cells were significantly more resistant to most stressors, including ethanol (10 to 30%, 5 min), sodium hypochlorite (10 to 100 ppm, 10 min), didecyl dimethyl ammonium chloride (0.05 to 0.25%, 5 min), hydrogen peroxide (0.5 to 2.0%, 30 min), NaCl (0.1 to 1 M, 2 h), bile salts (1 to 10%, 2 h), dry heat (100°C, 1 h), and UV irradiation (125 μW/cm<jats:sup>2</jats:sup>, 25 min). In contrast, exposure of<jats:italic>Salmonella</jats:italic>to acetic and citric acids reduced the survival of the dried cells (1.5 log) compared to that of nondesiccated cells (0.5 log). Three other<jats:italic>S. enterica</jats:italic>serotypes,<jats:italic>S</jats:italic>. Enteritidis,<jats:italic>S</jats:italic>. Newport, and<jats:italic>S</jats:italic>. Infantis, had similar stress responses as<jats:italic>S</jats:italic>. Typhimurium, while<jats:italic>S</jats:italic>. Hadar was much more susceptible and gained tolerance to only a few stressors. Our findings indicate that dehydration induces cross-tolerance to multiple stresses in<jats:italic>S. enterica</jats:italic>, demonstrating the limitations of current chemical and physical treatments utilized by the food industry to inactivate food-borne pathogens.</jats:p>