Biocontrol of multidrug-resistant Proteus mirabilis on chicken breast, pork tenderloin, and lettuce using the lytic bacteriophage vB_PMG_YP1.

Proteus mirabilis (P. mirabilis) is frequently detected in the food supply chain, particularly in meat and fresh produce. It carries antibiotic resistance genes (ARGs) and virulence factors, which pose significant risks to food safety and public health. Phages are considered a promising natural antimicrobial agent capable of effectively eliminating multidrug-resistant (MDR) pathogens. However, the application of phages to control MDR P. mirabilis in the food supply chain remains relatively limited. In this study, the P. mirabilis isolate carried seven virulence factors, one class 1 integron, and four ARGs, showing resistance to 94.74% (18/19) of the tested antibiotics. We isolated and characterized a lytic P. mirabilis phage, vB_PMG_YP1. Genomic analyses revealed that vB_PMG_YP1 belongs to the genus Privateervirus. vB_PMG_YP1 encodes tRNA genes and lacks genes associated with antibiotic resistance, virulence, or lysogeny. vB_PMG_YP1 maintained activity from 4 to 60 °C and across pH 3-11. The optimal multiplicity of infection (MOI) was 0.1, with a burst size of 240 phages per cell. The spot assay (60.87%, 14/23) and EOP test showed that vB_PMG_YP1 possesses a moderate lytic spectrum against P. mirabilis. vB_PMG_YP1 provided sustained suppression of P. mirabilis on chicken breast, pork tenderloin, and lettuce at 4 °C, whereas at 25 °C it achieved more rapid and robust inhibition. Under both 4 °C and 25 °C conditions, phage treatment did not significantly affect the color, texture, odor, or overall acceptability of any food matrix. These findings suggest vB_PMG_YP1 as a potential biocontrol candidate for reducing MDR P. mirabilis on food matrices.