Abstract: In this study, a virulent phage infecting Vibrio parahaemolyticus, designated vB_VpaP_FR4, was isolated and purified from a fish pond experiencing a vibriosis outbreak. Whole-genome sequencing, biological characterization, and analysis of its antibacterial effect in foods were carried out. Results showed that phage vB_VpaP_FR4 formed transparent plaques without halos, 1.2–2 mm in diameter. It was a short-tailed phage with an icosahedral head about 64 nm in diameter and a tail approximately 8 nm in length. Its genome was 42 784 bp in length, containing 48 open reading frames (ORFs), of which 24 encode proteins with known functions. It belonged to the Maculvirus genus of the Autographiviridae family. Biologically, phage vB_VpaP_FR4 lysed 62.7% of the tested V. parahaemolyticus strains and showed optimal infectivity at multiplicities of infection (MOI) ranging from 0.001 to 100. The one-step growth curve indicated a latent period of 5 min, a burst period of 30 min, and a burst size of 26 PFU/cell. The phage remained viable at 4–50 ℃ and pH 5–10. In fresh salmon slices stored at 4 ℃, vB_VpaP_FR4 reduced V. parahaemolyticus below the detection limit after 72 h. Meanwhile, bacteriophage treatment did not affect the sensory quality of salmon. Collectively, these results demonstrate the potential of vB_VpaP_FR4 as a V. parahaemolyticus-specific biocontrol agent.

Key words: Vibrio parahaemolyticus; virulent phage; biological properties; salmon slices; biocontrol