Bacteriophages are viruses that infect bacteria and typically follow either a lytic or lysogenic life cycle. In the lytic cycle, a phage attaches to a host cell, injects its genome, redirects host metabolism to produce progeny, and lyses the cell to release new virions. This rapid bactericidal process underlies their application as antimicrobial agents [49,50].
Host recognition is mediated by specific interactions between phage receptor-binding proteins and bacterial surface structures, including proteins, lipopolysaccharides, teichoic acids, or surface polysaccharides. These interactions largely determine host range and explain the narrow specificity of many phages, making receptor characterization critical when selecting phages for food applications [49,51].
Phage performance is strongly influenced by environmental conditions. Temperature, pH, ionic strength, and organic matter affect adsorption efficiency, replication, and particle stability, and must be considered when applying phages in food matrices or on processing surfaces. Formulation strategies, including encapsulation, are commonly used to improve stability under applied conditions [47,52].
Many lytic bacteriophages encode enzymes that promote bacterial lysis and biofilm disruption. Endolysins hydrolyze peptidoglycan to enable cell lysis, while phage-associated depolymerases degrade extracellular polysaccharides and capsule material, facilitating access to biofilm-embedded cells [53]. These enzymes can function independently as antimicrobial proteins or enhance phage penetration into biofilms when used in combination, making them attractive tools for surface sanitation and biofilm control [54,55].
Phage efficacy against biofilms is variable, as biofilm structure can restrict phage diffusion and protect embedded cells, even though planktonic populations are readily reduced [56]. Combining phages with depolymerases, endolysins, or complementary antimicrobials consistently improves biofilm disruption in laboratory and pilot-scale studies. Phage cocktails and phage and enzyme combinations generally outperform single-phage treatments against established biofilms [54,55,57].
Bacterial resistance to phages can arise through modification or loss of phage receptors, restriction modification systems, and CRISPR-based adaptive immunity [58]. These defenses influence phage performance and support mitigation strategies such as phage cocktails, periodic rotation, and engineered phages designed to expand host range or bypass resistance mechanisms [49,59].
Phage specificity is therefore both an advantage and a constraint. Narrow host range limits effects on beneficial microbiota but requires careful matching to target strains or use of multi-phage formulations. Regulatory-approved products illustrate this balance; for example, Listex™ P100 is a lytic phage preparation approved for control of L. monocytogenes in foods, demonstrating successful deployment of a well-characterized and targeted phage product [48,52].
3.2. Applications in Food Matrices and Processing Environments
Bacteriophages have been evaluated across diverse food types and processing conditions, with multiple studies reporting measurable log-scale reductions in pathogen levels under realistic application scenarios [60]. For L. monocytogenes, the lytic phage preparation Listex™ P100 has shown consistent reductions on ready-to-eat (RTE) meats, smoked fish, and fresh produce. Regulatory and risk assessments support its use in specific products, reflecting its efficacy and safety profile [48,61].
Phage treatments applied as sprays, dips, or surface washes typically produce reductions ranging from approximately 1 to 3 log colony-forming units per gram (CFU g−1), depending on matrix composition, temperature, phage concentration, and timing of application. For instance, phage cocktails reduced Shiga toxin producing Escherichia coli by about 1–2 log CFU g−1 on cucumbers and related produce in laboratory studies [62,63].
Meat and poultry processing have been frequent targets for phage application. Field and pilot-scale studies report that phage sprays can reduce Salmonella contamination on carcasses, with mean reductions of approximately 1–2 log CFU per surface area. Efficacy depends strongly on temperature, surface characteristics, and organic load, but commercial trials and industry reports indicate practical benefits when phages are integrated into processing workflows [64,65].
Fresh produce presents distinct challenges due to surface complexity and potential internalization. Several studies report initial reductions in Escherichia coli (E. coli) O157:H7 or L. monocytogenes on fresh-cut fruits and leafy greens following phage treatment, although regrowth may occur under favorable storage conditions. Combining phages with additional hurdles, such as refrigeration, washing, or antimicrobial compounds, improves sustained control [61,66].
Phage-derived enzymes, including endolysins and depolymerases, show strong activity against biofilms on food-contact surfaces. Endolysins rapidly lyse Gram-positive bacteria, while depolymerases degrade extracellular matrices that protect biofilm cells [67]. Laboratory and pilot studies show that enzymatic treatments reduce biofilm biomass and increase susceptibility to subsequent sanitation steps. These enzymes are being explored both as standalone interventions and in combination with whole phages [68,69].
Formulation and delivery remain critical determinants of efficacy. Encapsulation, surface immobilization, and incorporation into coatings or films can extend phage stability and activity. Immobilized phages may provide prolonged protection and reduce the frequency of application, provided that immobilization methods preserve infectivity and remain compatible with industrial cleaning practices [70,71].
Phage cocktails are commonly used to broaden host coverage and delay resistance development. Multiple studies and recent reviews show that cocktails often outperform single-phage preparations, particularly in complex matrices that contain diverse strains. Effective cocktail design depends on surveillance data to ensure coverage of relevant food-associated isolates [62,72].
Source: Elbehiry A, Alajaji AI. Next-Generation Strategies for Controlling Foodborne Pathogens: Precision Antimicrobials, Biofilm Disruption, and Emerging Molecular Interventions. Foods. 2026; 15(2):194. https://doi.org/10.3390/foods15020194