Abstract: Objective: To isolate and characterize a lytic bacteriophage against Escherichia coli O157:H7 and to evaluate its antibiofilm activity on food contact surfaces and its antibacterial effect on contaminated beef. Methods: A lytic bacteriophage was isolated using E. coli ATCC 35150 as the host strain. Its morphological characteristics were observed by transmission electron microscopy (TEM), and its genomic features were analyzed by whole-genome sequencing and phylogenetic analysis. Meanwhile, its host range, multiplicity of infection (MOI), one-step growth curve, and environmental stability were determined. Biofilm removal was evaluated using crystal violet staining and plate counting, and the antibacterial activity on beef stored at 4 and 25 ℃ was assessed by the gradient dilution-spread plate method. Results: A lytic bacteriophage, designated SF-E1, showing typical myovirus morphology, was successfully isolated. SF-E1 belonged to the family Straboviridae and the genus Mosigvirus, with a genome length of 171 055 bp and no detected virulence, antimicrobial resistance, or lysogeny-related genes. SF-E1 exhibited an optimal MOI of 0.01, a latent period of 20 min, and a burst size of 259 PFU/cell, and remained stable over a pH range of 3–11 at temperatures of 4–50 ℃. SF-E1 significantly inhibited E. coli O157:H7 biofilm formation and achieved a removal rate of over 90.00% on high-density polyethylene and stainless steel surfaces. In addition, SF-E1 effectively reduced E. coli O157:H7 on beef at both temperatures. Conclusion: Bacteriophage SF-E1 shows high lytic efficiency and strong antibiofilm activity against E. coli O157:H7, demonstrating its potential as a biocontrol agent in food safety applications.

Key words: Escherichia coli O157:H7; foodborne pathogenic bacteria; bacteriophage; biological characteristics