Skip to main content
ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Agroecosystems Management Research » Research » Publications at this Location » Publication #419136
Research Project: Physiological, Microbiological, and Nutritional Mechanisms to Maintain Animal Productivity in the Absence of Antibiotics

Location: Agroecosystems Management Research

Title: Localization of the origin of transfer for Salmonella genomic island 4 from Salmonella enterica serovar I 4,[5],12:i:-

Author
item NEUPANE, DURGA - Oak Ridge Institute For Science And Education (ORISE)
item Bearson, Bradley
item Bearson, Shawn

Submitted to: DNA Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2025
Publication Date: 9/15/2025
Citation: Neupane, D., Bearson, B.L., Bearson, S.M. 2025. Localization of the origin of transfer for Salmonella genomic island 4 from Salmonella enterica serovar I 4,[5],12:i:-. DNA Research. https://doi.org/10.1093/dnares/dsaf023.
DOI: https://doi.org/10.1093/dnares/dsaf023

Interpretive Summary: Salmonella enterica which frequently lives in the intestine of livestock and poultry is a known source of foodborne infection in humans. A common Salmonella strain (serovar I 4,[5],12:i:-) contains multiple antimicrobial resistance genes and is associated with food-animal production globally. This bacterial strain often contains a mobile DNA element in its chromosome that has metal tolerance genes for copper, silver, and arsenic. Previous studies have shown that the metal tolerance island can move from this strain to other bacteria, resulting in increased metal tolerance for the recipient strains. The DNA region that is required for movement of the island to other bacteria is unknown. In this study, the region containing the origin of transfer was identified by cloning a piece of DNA into an individual DNA element and demonstrating transfer to another bacteria. We confirmed the role of this DNA segment in the movement from one bacterium to another. These findings enhance our understanding of a DNA region involved in bacterial transfer of a metal tolerance island in one of the most frequent antimicrobial resistant Salmonella strains. These results can be used as a model system to investigate and understand the movement of metal tolerance genes in the food-animal production environment. This information will help scientists determine whether this DNA region is present in other bacteria.

Technical Abstract: Salmonella enterica serovar I 4,[5],12:i:- (serovar I 4,[5],12:i:-) is one of the most frequent multidrug-resistant (MDR) Salmonella serovars associated with food–animal production globally, and strains often contain Salmonella genomic island-4 (SGI-4), an integrative conjugative element (ICE) encoding metal tolerance for copper, silver, and arsenic. Horizontal gene transfer (HGT) of SGI-4 from serovar I 4,[5],12:i:- to recipient bacteria results in enhanced metal tolerance for the transconjugants; however, the origin of transfer (oriT) for SGI-4 mobilization is unknown. In this study, the oriT within SGI-4 of MDR serovar I 4,[5],12:i:- strain USDA15WA-1 was identified by (i) cloning an internal region of SGI-4 into a non-mobilizable plasmid and demonstrating HGT to a bacterial recipient, and (ii) deleting the predicted oriT region of SGI-4 from strain USDA15WA-1 and abolishing SGI-4 transfer. Sequence similarity to oriTSGI-4 was identified in other Enterobacteriaceae, and conjugation of SGI-4 occurred from USDA15WA-1 to Salmonella serovars from Serogroups C–E as well as Escherichia coli and Citrobacter. Localization of the SGI-4 oriT enhances our understanding of a DNA region involved in HGT of an ICE in a frequent MDR Salmonella serovar, thereby providing a model to investigate HGT of SGI-4 and dissemination of metal tolerance genes in the food–animal production environment.