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United States Department of Agriculture

Agricultural Research Service

Research Project: Biology and Control of Human Pathogens on Fresh Produce

Location: Produce Safety and Microbiology Research

Title: Identification of Salmonella enterica genes with a role in persistence on lettuce leaves during cold storage by recombinase-based in vivo expression technology

Authors
item Kroupitski, Yulia -
item Brandl, Maria
item Pinto, R -
item Belausov, E -
item Tamir-Ariel, D -
item Burdman, S -
item Sela, Shlomo -

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 7, 2013
Publication Date: March 19, 2013
Repository URL: http://dx.doi.org/10.1094/PHYTO-10-12-0254-FI
Citation: Kroupitski, Y., Brandl, M., Pinto, R., Belausov, E., Tamir-Ariel, D., Burdman, S., Sela, S. 2013. Identification of Salmonella enterica genes with a role in persistence on lettuce leaves during cold storage by recombinase-based in vivo expression technology. Phytopathology. 103:362-372.

Interpretive Summary: In light of the recurring outbreaks of food-borne illness linked to produce, there is an urgent need to understand the various plant and bacterial factors that enable the persistence of enteric pathogens on plant surfaces. In the present study we aimed at identifying Salmonella enterica Typhimurium genes required for its survival on lettuce leaves during cold storage. Using recombinase-based in vivo technology, we identified 37 S. Typhimurium loci that were induced on lettuce leaves during storage at 8C for seven days in four separate experiments. S. Typhimurium deletion mutants in four of the above loci, namely stfC, bcsA, yidR and misL were impaired in survival in our model system. stfC, bcsA, yidR and misL encode a fimbrial outer membrane usher, a protein cellulose synthase catalytic subunit, an autotransporter and a hypothetical protein, respectively. BcsA-, MisL- and YidR-minus mutants were impaired also in attachment to lettuce and biofilm formation, suggesting that these functions are required for survival on lettuce.

Technical Abstract: The lack of effective means to decontaminate fruits and vegetables and the continuous occurrence of outbreaks related to fresh produce, emphasize the need to understand the molecular basis of the persistence of human pathogens on fresh produce. In the present study we aimed at identifying Salmonella enterica Typhimurium genes required for persistence on lettuce leaves during cold storage using recombinase-based in vivo technology. A total of 37 potentially induced loci were identified in four distinct screenings. Knockout mutations in eight up-regulated genes revealed that four were necessary for persistence of the pathogen in this model system. These genes include stfC, bcsA, yidR and misL encoding a fimbrial outer membrane usher, a protein cellulose synthase catalytic subunit, an autotransporter and a hypothetical protein, respectively. Three mutants (BcsA-, MisL- and YidR-minus) were impaired also in attachment to lettuce and biofilm formation, suggesting that these functions are required for survival on lettuce. This is the first report that MisL, which has a role in Salmonella binding to fibronectin in animal hosts, is involved also in adhesion to plant tissue. Hence, our study uncovered a new plant attachment factor in Salmonella and demonstrates that RIVET is an effective approach also for investigating human pathogen-plant interactions in a post-harvest leafy vegetable.

Last Modified: 12/26/2014
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