title: Persistence of Salmonella enterica during dehydration and subsequent cold storage.
abstract: Despite the fact that Salmonella enterica serotype Typhimurium SL 1344 has served as a model pathogen in many studies, information regarding its desiccation response is still scarce. In this study, we investigated environmental conditions that affect Salmonella survival following dehydration and subsequent cold storage, using a 96-well polystyrene plate model. The SL 1344 strain exhibited high survival compared with other Typhimurium isolates and S. enterica serotypes. Further characterization of desiccation tolerance in this strain revealed that temperature, stationary-phase of growth, solid medium, and the presence of increasing NaCl concentrations (0.5-5.0%) in the growth medium enhanced desiccation tolerance. Dehydration at basic pHs (8-10), or in trehalose, sucrose, but not in glycine-betaine, improved bacterial persistence. Dehydrated Salmonella survived over 100 weeks at 4 °C with a ∼5-log reduction in numbers. However, viability staining revealed only a ∼50% reduction in viable cells, suggesting bacterial transition into a viable-but-not-cultivable state (VBNC). Addition of chloramphenicol reduced bacterial survival implying that adaptation to desiccation stress requires de-novo protein synthesis. Consistent with this finding, shortening the dehydration time resulted in lower survival. This study emphasizes the impact of environmental conditions on the fate of dried Salmonella in the food chain and highlights the potential transition of the pathogen to the VBNC state.
authors.affiliation: Microbial Food-Safety Research Unit, Department of Food Quality and Safety, Institute for Postharvest and Food Sciences, Agricultural Research Organization (ARO), The Volcani Center, POB 6, Beth-Dagan 50250, Israel.
authors.forename: Nadia
authors.initials: N
authors.lastname: Gruzdev
authors.forename: Riky
authors.initials: R
authors.lastname: Pinto
authors.forename: Shlomo
authors.initials: S
authors.lastname: Sela Saldinger
mesh_terms: D000818:Animals; D001715:Bird Diseases / Q000382:microbiology; D001717:Birds; D003080:Cold Temperature; D003890:Desiccation; D006801:Humans; D050296:Microbial Viability; D012480:Salmonella Infections / Q000382:microbiology; D012481:Salmonella Infections, Animal / Q000382:microbiology; D012486:Salmonella typhimurium / Q000737:chemistry / Q000254:growth & development* / Q000302:isolation & purification