Isolation and food-relevant evaluation of a novel lytic Kayfunavirus phage vB-EcoP-B10 for controlling STEC on food-contact surfaces and in raw beef.

Abstract

Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen, and beef-associated contamination remains a major food-safety concern. STEC in beef products is difficult to control when cells persist as biofilms on food-contact surfaces and in processing environments. Here, lytic phage vB-EcoP-B10 was isolated from cattle-farm wastewater using cattle-farm-derived STEC B10 as the host. Its genomic safety, biological properties, antibiofilm activity, and raw-beef efficacy were evaluated. TEM and genome analyses assigned vB-EcoP-B10 to a novel species within Kayfunavirus. Its 40,015-bp dsDNA genome encodes 48 ORFs and lacks detectable lysogeny, virulence, antimicrobial resistance, or tRNA genes. vB-EcoP-B10 lysed multiple pathogenic E. coli strains, including O157:H7, and selected Salmonella isolates. It showed a 10-min latent period, a burst size of 178 PFU per infected cell, and stability at pH 2.0-10.0, 20-60 °C, and after UV irradiation. vB-EcoP-B10 significantly inhibited STEC planktonic growth, reduced biofilm biomass and biofilm-associated viable cells, and disrupted mature biofilm architecture (P < 0.05). On stainless-steel coupons, it reduced biofilm-associated B10 by 2.9 log10 CFU/coupon and O157:H7 EDL933 by 1.6-2.6 log10 CFU/coupon. In raw beef, reductions of B10 and O157:H7 EDL933 reached 1.9-2.5 and 1.4-2.6 log10 CFU/g at 4 °C, and 3.7 and 2.0 log10 CFU/g at 25 °C, respectively (P < 0.05). The phage remained recoverable from raw beef without marked pH or perceptible color changes. These results support vB-EcoP-B10 as a residue-free candidate for STEC control on food-contact surfaces and in raw beef.