Comprehensive Characterization of a Novel Broad-Host-Range Lytic Salmonella Phage WP110 and Its Biocontrol Potential Across the Broiler Value Chain

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Background/Objectives: Salmonella enterica (S. enterica) is a major poultry-associated foodborne pathogen and a persistent public health concern. The global rise in antimicrobial resistance has accelerated the search for alternative control strategies, including the use of bacteriophages. However, their successful application requires a comprehensive evaluation of their biological performance, genomic safety, and functional proteins. This study aimed to characterize Salmonella phage WP110 and assess its potential as a biocontrol agent in broiler-associated production systems. Methods: Phage WP110 was evaluated against 251 S. enterica isolates from broiler-related sources. Adsorption kinetics, one-step growth, environmental stability (temperature and pH), and effective multiplicity of infection (MOI) were determined using Salmonella Kentucky S1H28. Whole-genome sequencing (WGS) and bioinformatic analyses were performed for genome annotation, taxonomic classification, and safety evaluation. In addition, protein structural prediction of a putative endolysin (WP110-gp057) was conducted using AlphaFold2, followed by structural comparison and molecular docking with peptidoglycan. Biocontrol efficacy was evaluated in contaminated rice husk, chicken meat, and on non-food materials. Results: Phage WP110 demonstrated a broad lytic spectrum, lysing 248/251 S. enterica isolates (98.8%). It adsorbed rapidly (within 3–15 min) to host cells and exhibited a latent period of ~20 min with a burst size of 134 particles per infected cell. Phage WP110 remained stable at 4–45 °C and pH 5–11 but was inactivated at ≥75 °C and pH 2. Complete bacterial inactivation in broth assay was achieved at an MOI of 104. Genomic analysis revealed a 110,216 bp linear dsDNA genome (39.74% GC) comprising 204 ORFs, 25 tRNAs, and long direct terminal repeats, with no detectable antibiotic resistance genes. Phylogenetic and intergenomic analyses classified phage WP110 as a novel species within the genus Epseptimavirus. Structural modeling of WP110-gp057 revealed conserved catalytic residues and high structural similarity to T5 endolysin, while docking analysis supported a structurally plausible interaction with peptidoglycan at the predicted active-site groove, consistent with its proposed role in host cell wall degradation. In application models, phage WP110 significantly reduced Salmonella contamination in rice husk (up to 4.3 log CFU/g), chicken meat (up to 1.7 log CFU/g), and on non-food material surfaces (0.7–1.5 log CFU reduction). Conclusions: Phage WP110 is a broad-host-range lytic phage with favorable infection kinetics, environmental robustness, and genomic safety. Its functionally supported endolysin and strong antibacterial efficacy across broiler-associated matrices highlight its potential as a biocontrol agent for Salmonella mitigation in poultry value chain.

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Related topics: Bacteriophages and microbial interactions · Salmonella and Campylobacter epidemiology · Cancer Research and Treatments