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Salmonella enterica Serovar Typhimurium 14028s Genomic Regions Required for Colonization of Lettuce Leaves
Year:
2020
Source of publication :
Frontiers in Microbiology
Authors :
סלע, שלמה
;
.
Volume :
11
Co-Authors:

Montano, J., Department of Plant Sciences, University of California, Davis, Davis, CA, United States, Plant Pathology Graduate Group, University of California, Davis, Davis, CA, United States; Rossidivito, G., Department of Plant Sciences, University of California, Davis, Davis, CA, United States, Plant Biology Graduate Group, University of California, Davis, Davis, CA, United States; Torreano, J., Department of Plant Sciences, University of California, Davis, Davis, CA, United States; Porwollik, S., Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, United States; McClelland, M., Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, United States; Melotto, M., Department of Plant Sciences, University of California, Davis, Davis, CA, United States

Facilitators :
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Total pages:
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Abstract:

Contamination of edible produce leaves with human bacterial pathogens has been associated with serious disease outbreaks and has become a major public health concern affecting all aspects of the market, from farmers to consumers. While pathogen populations residing on the surface of ready-to-eat produce can be potentially removed through thorough washing, there is no disinfection technology available that effectively eliminates internal bacterial populations. By screening 303 multi-gene deletion (MGD) mutants of Salmonella enterica serovar Typhimurium (STm) 14028s, we were able to identify ten genomic regions that play a role in opening the stomatal pore of lettuce leaves. The major metabolic functions of the deleted regions are associated with sensing the environment, bacterium movement, transport through the bacterial membrane, and biosynthesis of surface appendages. Interestingly, at 21 days post inoculation, seven of these mutants showed increased population titers inside the leaf, two mutants showed similar titers as the wild type bacterium, whereas one mutant with a large deletion that includes the Salmonella pathogenicity island 2 (SPI-2) showed significantly impaired persistence in the leaf apoplast. These findings suggest that not all the genomic regions required for initiation of leaf colonization (i.e., epiphytic behavior and tissue penetration) are essential for continuing bacterial survival as an endophyte. We also observed that mutants lacking either SPI-1 (Mut3) or SPI-2 (Mut9) induce callose deposition levels comparable to those of the wild type STm 14028s; therefore, these islands do not seem to affect this lettuce defense mechanism. However, the growth of Mut9, but not Mut3, was significantly impaired in the leaf apoplastic wash fluid (AWF) suggesting that the STm persistence in the apoplast may be linked to nutrient acquisition capabilities or overall bacterial fitness in this niche, which are dependent on the gene(s) deleted in the Mut9 strain. The genetic basis of STm colonization of leaves investigated in this study provides a foundation from which to develop mitigation tactics to enhance food safety. © Copyright © 2020 Montano, Rossidivito, Torreano, Porwollik, Sela Saldinger, McClelland and Melotto.

Note:
Related Files :
bacterial persistence
food safety
leafy vegetable
lettuce stress response
Salmonella mutant screen
עוד תגיות
תוכן קשור
More details
DOI :
10.3389/fmicb.2020.00006
Article number:
6
Affiliations:
Database:
סקופוס
Publication Type:
מאמר
;
.
Language:
אנגלית
Editors' remarks:
ID:
46217
Last updated date:
02/03/2022 17:27
Creation date:
18/02/2020 10:56
Scientific Publication
Salmonella enterica Serovar Typhimurium 14028s Genomic Regions Required for Colonization of Lettuce Leaves
11

Montano, J., Department of Plant Sciences, University of California, Davis, Davis, CA, United States, Plant Pathology Graduate Group, University of California, Davis, Davis, CA, United States; Rossidivito, G., Department of Plant Sciences, University of California, Davis, Davis, CA, United States, Plant Biology Graduate Group, University of California, Davis, Davis, CA, United States; Torreano, J., Department of Plant Sciences, University of California, Davis, Davis, CA, United States; Porwollik, S., Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, United States; McClelland, M., Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, United States; Melotto, M., Department of Plant Sciences, University of California, Davis, Davis, CA, United States

Salmonella enterica Serovar Typhimurium 14028s Genomic Regions Required for Colonization of Lettuce Leaves

Contamination of edible produce leaves with human bacterial pathogens has been associated with serious disease outbreaks and has become a major public health concern affecting all aspects of the market, from farmers to consumers. While pathogen populations residing on the surface of ready-to-eat produce can be potentially removed through thorough washing, there is no disinfection technology available that effectively eliminates internal bacterial populations. By screening 303 multi-gene deletion (MGD) mutants of Salmonella enterica serovar Typhimurium (STm) 14028s, we were able to identify ten genomic regions that play a role in opening the stomatal pore of lettuce leaves. The major metabolic functions of the deleted regions are associated with sensing the environment, bacterium movement, transport through the bacterial membrane, and biosynthesis of surface appendages. Interestingly, at 21 days post inoculation, seven of these mutants showed increased population titers inside the leaf, two mutants showed similar titers as the wild type bacterium, whereas one mutant with a large deletion that includes the Salmonella pathogenicity island 2 (SPI-2) showed significantly impaired persistence in the leaf apoplast. These findings suggest that not all the genomic regions required for initiation of leaf colonization (i.e., epiphytic behavior and tissue penetration) are essential for continuing bacterial survival as an endophyte. We also observed that mutants lacking either SPI-1 (Mut3) or SPI-2 (Mut9) induce callose deposition levels comparable to those of the wild type STm 14028s; therefore, these islands do not seem to affect this lettuce defense mechanism. However, the growth of Mut9, but not Mut3, was significantly impaired in the leaf apoplastic wash fluid (AWF) suggesting that the STm persistence in the apoplast may be linked to nutrient acquisition capabilities or overall bacterial fitness in this niche, which are dependent on the gene(s) deleted in the Mut9 strain. The genetic basis of STm colonization of leaves investigated in this study provides a foundation from which to develop mitigation tactics to enhance food safety. © Copyright © 2020 Montano, Rossidivito, Torreano, Porwollik, Sela Saldinger, McClelland and Melotto.

Scientific Publication
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