Genetic Determinants Associated with Persistence of Listeria Species and Background Microflora from a Dairy Processing Environment

Listeria monocytogenes is a persistent foodborne pathogen capable of surviving in food processing environments, often in association with diverse environmental microflora. This study examines genomic determinants of persistence, specifically stress adaptation and biofilm-associated traits, in environmental Listeria species and other environmental microflora from a dairy processing facility by analyzing whole-genome sequences of 6 environmental Listeria isolates, 4 ATCC reference strains, and 22 air and floor swab cultures, annotated using the RAST platform. Subsystem analysis revealed that Listeria isolates carried a defined set of genes linked to biofilm formation, antimicrobial resistance, and stress response, though in lower abundance than environmental cultures. Listeria exhibited fewer flagellar genes but greater consistency in core stress-related genes, including those for disinfectant and osmotic stress resistance, with SigB operon and RpoN genes highlighting strong stress tolerance. In contrast, environmental cultures exhibited broader transcriptional regulators (RpoE, RpoH) and greater diversity in acid and heat shock response genes, indicating distinct survival strategies. All examined Listeria species harbor biofilm and stress-resistance genes enabling independent survival, while environmental microbiota show greater genetic diversity that may promote persistence and multispecies biofilm formation. This study underscores the complex genetic landscape that may contribute to the persistence of Listeria and environmental microbiota in dairy processing environments, providing foundational insights for environmental cross contamination control strategies.