A bacteriophage cocktail for reducing Escherichia coli contamination in lettuce during storage conditions

Foodborne illnesses caused by Escherichia coli remain a major public health concern because of their impact on food safety and the role of E. coli as a reservoir of antimicrobial resistance genes. Bacteriophages have emerged as promising biocontrol agents due to their host specificity, safety, and ability to selectively target bacterial. In this study, a lytic three-phage cocktail, was developed and evaluated for the control of E. coli in lettuce stored under refrigerated (4°C) and ambient (25°C) conditions. Phages were selected based on their lytic activity, host range, and complementary infectivity profiles against reference and wastewater-derived E. coli strains. The antimicrobial efficacy of the cocktail was assessed in lettuce artificially contaminated with E. coli ATCC 25922 or B1348 (MOI 1000; 1 × 10⁸ PFU/mL per phage), and bacterial populations were quantified after 6 and 24 h. The cocktail significantly reduced E. coli ATCC 25922, achieving maximum reductions of 2.64 log CFU/g after 6 h at 25°C and 2.47 log CFU/g after 24 h at 4°C (p < 0.001). No significant reduction was observed for strain B1348. These findings demonstrate the potential of wastewater-derived lytic phages as biocontrol agents to improve the microbiological safety of fresh produce.