Whole-genome analysis of a polyvalent Salmonella phage reveals its potential to combat intracellular infection and food contamination.

Abstract

Salmonella infections represent a significant challenge to global public health, a situation further complicated by the rising prevalence of antibiotic resistance. In this study, a broad-spectrum phage, designated vB_SaeS_BG-2P, capable of efficiently lysing S. 4,[5],12:i:-and S. Kentucky, which are among the predominant serovars associated with human salmonellosis, was identified. The phage demonstrated a lytic efficiency of >98.3% against selected serovars (n = 5) of Salmonella isolates and also infected various Enterobacteriaceae, including Shigella flexneri, Escherichia coli and Klebsiella pneumoniae. With a complete genome length of 56,672 bp (a linear double-stranded DNA genome), phage BG-2P exhibited high nucleotide sequence homology with Salmonella phage vB_SalM_Sz (98.14%) and Escherichia phage vB_EcoM_swi3 (98.50%). Whole-genome average nucleotide identity analysis indicated that BG-2P shared a common genetic origin with Salmonella phages and belonged to the genus Rosemountvirus. The high number of cloud genes reflected considerable heterogeneity among the known Salmonella phages. The intracellular anti-Salmonella effects of phage BG-2P showed a positive correlation with the phage concentration during epithelial cell infection. Additionally, our results indicate that phage BG-2P administered via aerosol spraying reduced bacterial populations within 2 h in tests simulating space sterilization environments. Furthermore, the phage effectively suppressed Salmonella contamination in chickens at low temperatures (4 °C) within a few hours. In conclusion, the Rosemountvirus phage BG-2P exhibited a broad host range and effectively eliminated pathogenic infections when sprayed in space and on food surfaces. Unlike antibiotics, which are often ineffective against intracellular bacterial infections, this phage offers a viable alternative for combating intracellular pathogens, underscoring its significant potential for practical applica