Abstract:[Background] The abuse of antibiotics has exacerbated the drug resistance of pathogens, and the research on the use of phages in the treatment of multidrug resistant pathogens has attracted extensive attention. [Objective] This study aims to isolate new Escherichia coli phages and give insights into the application of phage therapy in the treatment of foodborne E. coli infections. [Methods] With multidrug resistant E. coli 6-3 as the host bacterium, the double-layer agar plate method was employed to isolate phages from the sewage of the farm. Plaque counting was conducted to determine the optimal multiplicity of infection (MOI), one-step growth curve, host range, thermal stability and other biological characteristics of phages. Next-generation sequencing was employed to obtain the whole genome sequences of phages, and the genomic and comparative genomics analyses were performed. [Results] The E. coli phage EcoM_GaoY6-3C had an optimal MOI of 1, an incubation period of 5 min, and stable potency at -70 ℃ to 50 ℃ and pH 3.0–11.0. The results of host profiling showed that this phage could infect pathogenic E. coli O157:H7. The genome assay results revealed that its genome was double-stranded circular DNA, with a length of 171 703 bp and repeat sequences of 111 bp at both ends. The genome had the G+C content of 40.28% and included 91 protein-coding genes and 2 tRNA-coding genes. The comparative genomics analysis revealed that EcoM_GaoY6-3C was a novel E. coli phage. Preliminary application experiments indicated that EcoM_GaoY6-3C effectively killed host bacteria in milk at 4 ℃, demonstrating promising practical applications. [Conclusion] EcoM_GaoY6-3C is a new E. coli phage and can be used for food safety control.
