Phenotypic characterization and biocontrol application of bacteriophage P53F with potent lytic and antibiofilm activities against Salmonella Pullorum.

Salmonella Pullorum (S. Pullorum) remains a persistent challenge in poultry production owing to its capacity to cause latent infections and spread through contaminated eggs and rearing facilities. Furthermore, biofilm formation and increased resistance to conventional control measures complicate its eradication. This study characterized a lytic bacteriophage (P53F) isolated from environmental wastewater and assessed its potential as a biological control agent. P53F exhibited strong lytic activity against multiple clinical isolates of S. Pullorum, with a latent period of 10 min and a burst size of 117 PFU/cell. Additionally, P53F maintained stability over a wide range of temperatures (4-60 °C) and pH levels (3.0-12.0) after a 1-h incubation. Morphological analysis revealed that P53F possesses an icosahedral head and a non-contractile tail, indicating a siphovirus morphotype. Genomic and phylogenetic analyses classified P53F within the genus Jerseyvirus (class Caudoviricetes). No virulence or antimicrobial resistance genes were detected. In vitro assays conducted at 25 and 37 °C demonstrated that P53F significantly inhibited S. Pullorum biofilm formation and disrupted mature biofilms. Moreover, when applied to contaminated eggshells and different material surfaces (stainless steel, glass, and polyethylene terephthalate), P53F at a multiplicity of infection of 1 significantly reduced S. Pullorum loads compared to the untreated control. These findings indicated that P53F is a promising biocontrol agent for controlling the spread of S. Pullorum in the poultry industry.