Abstract: This study aimed to isolate a phage that can lyse bla_NDM-5and mcr-1 positive Escherichia coli, explore the biological characteristics of the phage, and provide a certain theoretical basis for phage therapy. The isolated phage was observed by transmission electron microscope, the optimal multiplicity of infection, one-step growth curve and other biological characteristics experiments and whole genome sequencing analysis. A strain of E. coli phage vB_EcoM-ZQ1 was successfully isolated. The phage belonged to the order Ceratoviridae and the Mycoviridae family. The optimal multiplicity of infection was 0.1, the incubation period was 20 min, the lysis period was 10 min, and the amount of lysis was 92 PFU·cell^-1. Under the conditions of temperature 4-55℃ and pH4-10, the phage had high activity. It had a certain lysis effect on multi-drug resistant E. coli, with a lysis rate of 25.5%. The phage gene had a total length of 149 112 bp and a GC content of 49.1%. Among 184 ORFs, 70 ORFs encoded functional proteins, and 2 ORFs encoded tRNAs, and no drug resistance genes and virulence factors were found; The BLAST comparison found that the phage had 92.37% similarity with Shigella phage phiSboM-AG3. The results of a homologous phylogenetic tree constructed based on the large subunit of the phage terminal enzyme showed that the phage vB_EcoM-ZQ1 was closely related to the Salmonella phage pSal-SNUABM-02. The results indicated that the bacteriophage vB_EcoM-ZQ1 had stable biological characteristics and complete gene structure, which had laid a certain preliminary foundation for the follow-up prevention and control of bla_NDM-5 and mcr-1 positive E. coli.

Key words: phage, biological characteristics, Escherichia coli, bla_NDM-5, mcr-1