Abstract: Benzalkonium chloride (BAC) is a quaternary ammonium disinfectant widely applied in food processing and environmental sanitation. Repeated exposure to sub-inhibitory residue levels of BAC induces adaptive responses in foodborne pathogens and reshapes their virulence phenotype across multiple aspects. Existing studies indicate that BAC-adapted strains exhibit diverse alterations in key virulence traits, including biofilm formation, toxin production, hemolytic activity, adhesiveness, invasiveness, and host lethality, most of which are enhanced to varying extents. These phenotypic shifts are underpinned by multi-layered mechanisms, such as modulation of virulence gene expression, genetic mutations and horizontal gene transfer, remodeling of membrane composition, activation of efflux pumps, enhancement of quorum-sensing signals, and induction of viable but non-culturable states. Such adaptive responses not only enhance bacterial persistence along the food chain but also potentially elevate pathogenicity in hosts, posing potential food safety risks. This paper systematically summarizes the correlation between BAC adaptation and changes in typical virulence factors of foodborne pathogens. It helps to reveal the evolutionary patterns of pathogen virulence driven by disinfectant residues, providing a theoretical basis and technical references for optimizing disinfectant usage strategies, developing targeted inhibitors, and improving microbial risk assessment frameworks.

Key words: benzalkonium chloride; foodborne pathogens; virulence alterations; adaptive mechanism; food safety