Data to: Host-associated fitness determinants support Salmonella Choleraesuis persistence on fresh-cut onions

Citation: Beck, Maximilian and Führer, Laura and Porwollik, Steffen and Chu, Weiping and Hohenester, Verena and Sah, Irmak and McClelland, Michael and Guldimann, Claudia and Esteban-Cuesta, Irene: Data to: Host-associated fitness determinants support Salmonella Choleraesuis persistence on fresh-cut onions. 18. September 2026. Open Data LMU. 10.5282/ubm/data.839

Abstract

Fresh diced onions are increasingly consumed as ready-to-eat ingredients in the growing convenience food market. Because in this context onions do not undergo heat treatment, understanding the genetic mechanisms controlling Salmonella persistence on this food matrix is critical for developing precision food safety strategies. In this study, a barcoded transposon mutant library comprising 35,432 unique insertion mutants in a plant-derived S. enterica serovar Choleraesuis strain was used to identify genetic mechanisms contributing to fitness on onions during cold storage at 8°C. Insertions in 350 insertion mutants resulted in negative fitness effects, including 138 located in intergenic regions, 42 hypothetical proteins and 170 genes with assigned functions, 42 of which are classically associated with host-infection or virulence. Competitive fitness assays confirmed food matrix-specific fitness effects for mutants with disruptions in ail_1, encoding a cell attachment and invasion protein, and spaP_1, a key type III secretion system component. Furthermore, no growth was observed for mutants with insertions in acrB_1, encoding an acridine efflux pump component, and spaQ_1, also involved in the type III secretion system. Polar effects were identified for four genes (oxyR_1, csgD, mnmG, and yciF), where fitness impact depended on the insertion orientation. Our study highlights how onions provide an environment that elicits mechanisms similar to those encountered during host infection. Comparative analysis reveals shared pathways with S. Enteritidis but limited overlap with S. Typhimurium, underscoring serovar-specific variations in their environmental adaptive response. These insights support the identification of control targets for precision food safety interventions along the production and storage chain.

Uncontrolled Keywords

transposon insertion sequencing, salmonellosis, microbial contamination, transposon library, food safety

• Item Type: Data
• Contact Person: Beck, Maximilian and Esteban-Cuesta, Irene
• E-Mail of Contact: M.Beck at ls.vetmed.uni-muenchen.de, Irene.Esteban at ls.vetmed.uni-muenchen.de
• Subjects: Veterinary Medicine
• Dewey Decimal Classification: 500 Natural sciences and mathematics > 570 Life sciences