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.

During food processing and storage, the food industry often uses various stress technologies such as low-temperature refrigeration, acidification treatment, and chemical disinfection to inhibit the growth of microorganisms. Listeria monocytogenes is a psychrophilic bacterium with extremely strong tolerance to adverse environments, enabling it to persist for a long time in the processing environment, facilities and food products. The bacterial cell membrane serves as a structural barrier between the external environment and the cytoplasm, being a key target for bacterial adaptation to environmental stress. Fatty acids, the major components of the bacterial cytoplasmic membrane, not only participate in the assembly of membrane structures but also play a crucial role in the adaptive regulation of cells in response to environmental stress. This paper provides a systematic review of the current status of research on the adaptation of membrane lipids of L. monocytogenes to environmental stresses with a focus on low-temperature stress treatment. It elucidates the pattern of variations in the composition and structure of membrane lipids under different stress conditions, delves into the regulatory mechanisms of membrane fluidity and virulence factor expression, and proposes future research directions. Studies have shown that when microorganisms face external pressure, modification of membrane fatty acids is a key strategy to maintain cell membrane integrity and function. In-depth analysis of how bacterial membrane lipids adapt to different environmental stresses will provide an important theoretical basis for preventing and controlling the contamination of L. monocytogenes and thus ensuring food safety.

Listeria monocytogenes (L. monocytogenes) is a food-borne pathogen causing listeriosis, a sickness with high hospitalization rate and high mortality rate, and it can adhere to food contact surfaces under various adverse conditions such as cold, heat, dryness and disinfectant to form biofilms that are hard to remove. Cross-contamination is the major transmission route of L. monocytogenes, and biofilm formation increases the possibility of persistent transmission and contamination of L. monocytogenes in factory and kitchen environments, which may lead to the outbreak of food-borne diseases and food recalls, causing health and economic loss. In this article, the extracellular polymeric components of L. monocytogenes biofilms are introduced, and the internal and external factors affecting the cross-contamination and transfer of L. monocytogenes biofilms are summarized. A particular focus is placed on the recent progress in research on L. monocytogenes cross-contamination from the perspectives of research type and bacterial collection. In addition, we summarizes the prevention and control strategies for L. monocytogenes in the early stage of biofilm formation. Finally, the future prospects of this research field are proposed. We hope that this review could provide a theoretical basis for the scientific evaluation and accurate early prevention and control of the potential risk of L. monocytogenes biofilm cross-contamination.