Genomic insights into the evolution and adaptation of Listeria monocytogenes in poultry production systems

Authors: ZHANG, LI - Mississippi State University; SATOSHI, ISHII - University Of Minnesota; Rothrock Jr, Michael; Oladeinde, Adelumola; LI, XIANG - University Of Tennessee

Submitted to: Food Research International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/9/2026
Publication Date: 3/12/2026
Citation: Zhang, L., Satoshi, I., Rothrock Jr, M.J., Oladeinde, A.A., Li, X. 2026. Genomic insights into the evolution and adaptation of Listeria monocytogenes in poultry production systems. Food Research International. https://doi.org/10.1016/j.foodres.2026.118941.
DOI: https://doi.org/10.1016/j.foodres.2026.118941

Interpretive Summary: In this study, we investigated how Listeria monocytogenes, a bacterium that can cause serious foodborne illness, has changed and adapted within poultry production over the past century. By analyzing the genomes of nearly 1,800 isolates collected between 1940 and 2024, we were able to trace how this pathogen responded to major shifts in food production. We found that Listeria populations expanded rapidly during the growth of industrial poultry farming in the mid-1900s, then declined after new food safety measures were put in place. We also discovered that the bacterium’s genetic makeup is highly flexible, allowing it to adapt to many environments, from chicken and eggs to pet food. Interestingly, while Listeria continues to adapt to different niches, the major genes that make it capable of causing disease remain unchanged. This means the threat of illness from Listeria has not diminished, even as the food system has evolved. Our findings highlight how large-scale changes in agriculture and food safety policies can shape the evolution of pathogens, and exemplify the value of using genomic tools for ongoing surveillance to better protect public health.

Technical Abstract: Listeria monocytogenes (Lm) is a significant foodborne pathogen whose evolution has been shaped by the expansion of industrial food systems. To investigate these adaptive dynamics, we conducted a comprehensive genomic analysis of 1,788 poultry-associated Lm isolates collected between 1940 and 2024. We integrated phylogenomic, demographic modeling, and pangenome analyses to reconstruct the pathogen’s evolutionary history in response to anthropogenic pressures. Our pangenome analysis revealed an open pangenome with an extensive accessory genome (65.17% cloud genes), indicating remarkable genomic plasticity. Demographic reconstruction identified a five-fold increase in effective population size from 1940 to a peak around 1980, coinciding with the industrialization of poultry production. This expansion was followed by a sharp decline, likely reflecting the implementation of modern food safety interventions. Genome-wide association studies identified distinct sets of accessory genes significantly associated with specific isolation sources, including chicken, egg, and pet food, with pet food isolates showing exceptional genetic distinctiveness. Despite this extensive environmental adaptation, core virulence determinants were highly conserved across all isolates, confirming the maintenance of pathogenic potential. Collectively, these findings demonstrate that industrial food systems are the primary driver of Lm evolution, promoting niche specialization while preserving virulence. This research underscores the necessity of integrating pangenome-based surveillance into food safety frameworks to better anticipate and mitigate risks.