Isolation and characterization of a broad-spectrum Salmonella phage targeting featural foodborne serotypes

The pathogen-specific lytic activity of bacteriophages has rendered them a highly promising antibacterial agent to control Salmonella, a critical foodborne pathogen with increasing antibiotic resistance. However, the issue of phage-resistant strains severely hindered phage applications.

This study isolated a broad-spectrum bacteriophage JN06 from wastewater. The morphology/host range, infection capacity/stability and genome characteristics of JN06 were determined. Phage JN06 was evaluated in both biofilm inhibition and lettuce decontamination, followed by inoculation with Salmonella. The receptor for phage JN06 was identified by comparing adsorption abilities in resistant derivatives as well as mutants of gene deletion with S. enteritidis SMT.

JN06 (classified into Jerseyvirus based on nucleotide homology) can lyse Salmonella strains of various serotypes, with a short latent period (6 min), a large burst size (131 PFU/infected cell), and high stability at different temperatures (4 °C-70 °C) and pH (2-12). Furthermore, no determinants associated with lysogenicity, virulence, or antibiotic resistance were detected in its genome. Notably, it exhibited a biofilm formation inhibition rate of 86.58%, and completely controlled Salmonella from artificially contaminated lettuce. O-antigen was identified as the likely adsorption recipient, and molecular docking revealed that the specific binding between its tail fiber protein and the main chain of Gal-initiated O-antigen, D-Manp-(1 → 4)-L-Rhap-(α1 → 3)-D-Galp, underlying JN06's lytic activity against multiple serotypes of Salmonella.

Collectively, phage JN06 is a highly promising antibacterial agent for controlling Salmonella, benefiting food processing and disease prevention.