The Broad Ecological Range of Salmonella enterica Serotype Typhimurium Is Associated With Genomic Diversification.

Swine-derived Salmonella enterica serotype Typhimurium shows the most open pangenome and the highest prevalence of antimicrobial resistance genes, linked to mobile genetic elements, especially plasmids.

• Why it matters: Understanding how S. Typhimurium adapts across hosts and environments requires identifying genomic features that differ by food-animal source and predict ecological breadth.
• What they did: The study analyzed 595 genomes from bovine, swine, and poultry (food animals) and wild birds (non-food), comparing pangenome openness, ARG content, mobile genetic elements, and positive selection in core and accessory genomes, then using machine learning to find source-predictive variants.
• The result: Source-specific positive selection patterns in the core genome and source-predictive stress-response variants were detected, suggesting accessory gene turnover and core-gene selection support differential adaptation across sources.

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