A biologically pure strain of Escherichia Page SFI has the potential to control Escherichia coli during the processing of milk and salads.

Abstract

The biologically pure Escherichia phage SF1 strain was isolated from a sample of wild boar feces collected in Bac Ninh province, Vietnam. The strain has a nearly spherical, polyhedral head attached to a long, slender tail without a clearly defined contractile sheath. The head diameter is approximately 59.9 nm, the tail length is approximately 108.6 nm, and it carries a double-stranded DNA genome of 50,247 bp. It belongs to the Drexlerviridae family. The strain has a broad host range against Escherichia coli strains, including E. coli K12, E. coli BL21, and E. coli 0157, and exhibits strong lytic activity against E. coli 0157, a Shiga toxin-producing strain. The strain achieved approximately 95.2% E. coli eradication after 8 hours of culture at an MOI of 0.0001, with a latent period of about 30 minutes, outbreak size of approximately 80-120 PFU per lysed cell, maintaining activity up to 60°C and within a pH range of 6.0–8.0. When applied in food, the strain completely lysed E. coli in milk at 25°C after 12 hours with an MOI of 1.0, completely lysed E. coli at 4°C after about 24 hours, and effectively controlled E. coli.E. coli found on the surface of lettuce shows potential applications in food safety assurance.