title: Induction of Viable but Nonculturable Salmonella in Exponentially Grown Cells by Exposure to a Low-Humidity Environment and Their Resuscitation by Catalase.
abstract: Salmonella is a major cause of foodborne disease that sometimes occurs in massive outbreaks around the world. This pathogen is tolerant of low-humidity conditions. We previously described a method for induction of viable but nonculturable (VBNC) Salmonella enterica serovar Enteritidis by treatment with hydrogen peroxide (H2O2) and subsequent resuscitation with 0.3 mM sodium pyruvate. Here, we report a new method for the induction of the VBNC state in Salmonella Enteritidis cells, one involving dehydration. Exposure of Salmonella Enteritidis cells to dehydration stress under poor nutritional conditions (0.9% [wt/vol] NaCl) and 10 to 20% relative humidity at room temperature decreased the presence of culturable population to 0.0067%, but respiratory and glucose uptake active populations were maintained at 0.46 and 1.12%, respectively, meaning that approximately 1% may have entered the VBNC state. Furthermore, these VBNC cells could be resuscitated to acquire culturability by incubation with catalase in M9 minimal medium without glucose in a manner dependent on the dose of catalase but not sodium pyruvate. These results suggest that a low-humidity environment could cause Salmonella Enteritidis cells to enter the VBNC state and the cells could then be resuscitated for growth by treatment with catalase, suggesting a potential risk of Salmonella Enteritidis to survive in low water activity foods in the VBNC state and to start regrowth for foodborne illness.
authors.affiliation: Laboratory of Biodefense and Regulation, Osaka University of Pharmaceutical Sciences, Nasahara, Takatsuki, Osaka 569-1094, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Morishige
authors.affiliation: Laboratory of Biodefense and Regulation, Osaka University of Pharmaceutical Sciences, Nasahara, Takatsuki, Osaka 569-1094, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Koike
authors.affiliation: Laboratory of Biodefense and Regulation, Osaka University of Pharmaceutical Sciences, Nasahara, Takatsuki, Osaka 569-1094, Japan.
authors.forename: Ai
authors.initials: A
authors.lastname: Tamura-Ueyama
authors.affiliation: Laboratory of Biodefense and Regulation, Osaka University of Pharmaceutical Sciences, Nasahara, Takatsuki, Osaka 569-1094, Japan.
authors.forename: Fumio
authors.initials: F
authors.lastname: Amano
mesh_terms: D002374:Catalase; D004777:Environment; D006801:Humans; D006813:Humidity; D006861:Hydrogen Peroxide; D012477:Salmonella enteritidis
chemical_list: D006861:Hydrogen Peroxide; D002374:Catalase
keywords: Catalase; Low-humidity resistance; Salmonella; Viable but nonculturable