关键词: 大肠杆菌, 噬菌体, 鉴定, 噬菌体受体

Abstract: A strain of phage, designated vB_EcoS_IME18 (IME18), was isolated using Escherichia coli BL21 as the indicator bacterium. The morphology of the phage was observed by electron microscopy and the multiplicity of infection, one-step growth curve, lysis spectrum and in vitro bactericidal effect were determined; the genomic sequencing was performed by Illumina MiSeq sequencer and genomic features were analyzed by comparative genomics; the cause of phage resistance was analyzed by screening for phage resistant strains and confirmed by receptor gene silencing mutation, phage spotting, and phage adsorption assay. The results showed that phage IME18 had an icosahedral head and a non-contractile tail, belonging to the T1-like in the Tunavirinae subfamily in the family of Siphoviridae. The multiplicity of infection of phage IME18 was 0.01, latent period 5 min, burst period 50 min and burst size 223 PFU/cell; in vitro, phage IME18 could effectively kill BL21 in the log phase in 90 min. The total length of the genome was 50 354 bp with a G + C content of 45.6%. In addition, the proteins FhuA and TonB were proved to play a key role in the adsorption and infestation of phage IME18.

Key words: Escherichia coli, bacteriophage, identification, phage receptor