Abstract:Objective Yersinia enterocolitica is the primary pathogenic agent of yersiniosis, and it is one of the major foodborne pathogens worldwide. The purpose of this study is to isolate and identify a virulent phage against Y. enterocolitica and explore its application potential.Methods A novel virulent phage, named Yersinia phage Yen-yong1 (abbreviated as Yen-yong1), was isolated from the sewers of Lulin Market in Beilun District, Ningbo City, Zhejiang Province, China, by the double-layer agar method with Y. enterocolitica CICC 10869 as the indicator host. The morphology, host range, genome sequence, gene functions, phylogenetic position, physical and chemical tolerance, and biofilm removal ability of Yen-yong1 were studied. Additionally, the sterilization effect of Yen-yong1 on Y. enterocolitica in raw pork slices was evaluated.Results Yen-yong1 clarified the turbid CICC 10869 culture within 1.5 h. Yen-yong1 was Siphovirus-like, consisting of an elliptical head with a length of (83.32±0.15) nm and a width of (59.57±2.28) nm and a long tail with a length of (168.04±3.21) nm. The double-stranded DNA genome of Yen-yong1 was 51 321 bp, with the G+C content of 47.80% and 93 open reading frames (ORFs). No known lysogeny-associated genes, resistance genes, or virulence genes detrimental to application were found in Yen-yong1. The highest nucleotide sequence similarity between Yen-yong1 and the other phages in public databases was 20.64%, which was <70.00% (the threshold to define a genus). Yen-yong1 shared 20.00% of core genes with the closest relative, which was lower than the ICTV criteria for subfamily classification (27.00%?79.00%). The results suggested that Yen-yong1 represented a novel genus and a novel subfamily belonging to Caudoviricetes. Yen-Yong1 was species-specific and capable of lysing 3 out of 4 tested Y. enterocolitica strains. Yen-yong1 maintained high bacteriolytic activity at -80?60 ℃ and pH 2.0?13.0, as well as in the presence of 0?3% NaCl. Yen-yong1 can disrupt the biofilms of Y. enterocolitica. At 25 ℃ and MOI=100, the sterilization rates of Yen-yong1 against Y. enterocolitica CICC 10869, CICC 21669, and CMCC 52202 in raw pork slices were 93.48%, 52.77%, and 43.24%, respectively. All the 3 tested Y. enterocolitica strains proliferated at 4 ℃. At 4 ℃ and MOI=100, the sterilization rates of Yen-yong1 against Y. enterocolitica CICC 10869, CICC 21669, and CMCC 52202 in raw pork slices were 98.28%, 78.35%, and 96.33%, respectively.Conclusion Yen-Yong1 reveals a previously unknown evolutionary lineage. Yen-Yong1 has excellent biological characteristics and potential applications. This study enriches the knowledge of Y. enterocolitica phages, phage database, and gene database, laying a foundation for the application of phages in the prevention and control of food-borne yersiniosis.