Characterization of two virulent Proteus mirabilis phages and application of phage cocktail in raw chicken safety.

Proteus mirabilis is an opportunistic pathogen belonging to the genus Proteus in the Morganellaceae. It is closely associated with infections of the gastrointestinal and urinary systems in humans and animals, posing a threat to the safety of food industries. With the increasing abuse of antibiotics, the problem of bacterial resistance has become extremely urgent. Moreover, animal-source foods often have drug residues, making it an urgent need to explore alternatives to antibiotics. Bacteriophages, bacteria-lysing viruses, cause no biological pollution and do not induce bacterial antibiotic resistance, making them potential green biological bactericides. In this study, 24 pathogenic P. mirabilis strains were isolated as host bacteria. Two virulent bacteriophages, Proteus phage ABTNL-P14 (referred to as P14) and Proteus phage ABTNL-Pp2 (referred to as Pp2), were isolated and identified, both showing effective infectivity against P. mirabilis. Two phages were confirmed as virulent strains lacking virulence factors, lysogeny-related genes and antibiotic resistance genes, meeting safety criteria for food applications. This study also evaluated the effectiveness of a P14 and Pp2 phage cocktail in eliminating P. mirabilis from chicken breast meat at 4 °C under MOIs of 1, 100, and 10,000. Notably, at a high MOI (10,000), the phage cocktail eliminated two host strains on chicken breast meat surfaces within 1 h and 6 h. Therefore, the phage cocktail has the potential to eliminate P. mirabilis in foods at low temperatures, serving as a green antibacterial agent for food applications.