Identification and characterization of lytic bacteriophages specific to foodborne pathogenic Escherichia coli O157:H7

Abstract

The objective of this study was to identify and characterize five different lytic bacteriophages specific to Escherichia coli O157:H7. vB_EcoM-P12, vB_EcoM-P13, vB_EcoM-P23, and vB_EcoM-P34 phages belonged to the Myoviridae family and vB_EcoS-P24 phage was in the Siphoviridae family. Their plaque sizes changed between 0.48 ± 0.03 and 0.90 ± 0.03 mm in diameter. stx1 and stx2 virulent gene regions were absent in the genome of five Eco-phages and their genome size was 33 kbp. The protein band profiles of the five phages were found to be different from each other. Their latent period, burst size, and burst time changed between 10–15 min, 72–144 PFU/cell and 20–35 min, respectively. Multiplicity of infection values and mutant frequency of the phages were among 0.1–0.001 and 1.14 × 10⁻⁷–3.69 × 10⁻⁸, respectively. The phages had strong lytic activity against their host bacteria (E. coli NCTC 12900, ATCC 43888, and ATCC 35150) at 5–37 ℃ and adsorbed to their host cells by 92.7–97.5% in the first five minutes of incubation. These phages are thought to be good candidates as therapeutic and biocontrol agents against E. coli O157:H7 in the veterinary science and food industry due to short latent period, high burst size, rapid development in host cells, high lytic activity, high adsorption rate, stability over a wide pH range and high temperature, and absence of stx1 and stx2 genes.