1株多重耐药大肠杆菌噬菌体的分离、鉴定、生物学特性及全基因组分析

Isolation,Identification,Biological Characteristics and Whole Ge⁃nomic Analysis of a Multi-drug Resistant E.coli phage

以多重耐药大肠杆菌F2为宿主菌,从养殖场污水中分离出1株肌尾裂解性噬菌体vB_EcoM_F2。该噬菌体可侵染多株大肠杆菌,一般生物学特性分析表明最佳感染复数为1,潜伏期30 min,爆发期90 min,爆发量为101 PFU/cell;对氯仿不敏感,可在40~50℃、pH 4.0~10.0的条件下保持较高活性;全基因组测序结果表明其基因组长为168241 bp,(G+C)%含量为37.32%,含263个开放阅读框,其中113个为已知功能编码序列,含有2个tRNA;不含溶源基因、毒力因子和抗生素耐药基因;全基因组及终末端酶大亚基系统发育树的同源性分析表明,该大肠杆菌噬菌体vB_EcoM_F2与志贺菌噬菌phi25-307亲缘关系较近,但它不能侵染志贺菌属的标准菌株。目前,国际病毒分类委员会(ICTV)及美国国家生物技术信息中心资源(NCBI)已将其归类于肌尾噬菌体科(Myoviridae),Tevenvirinae亚科,Mosigvirus属,未分类的Mosigvirus物种(unclassified Mosigvirus),这就将为大肠杆菌病的噬菌体应用及防控奠定基础。

Using a multi-drug resistant Escherichia coli F2 as host strain,a Myoviridae lytic phage,vB_EcoM_F2,was isolated from farm sewage.Phage vB_EcoM_F2 could infect most test strains of E.coli.The general characteristic analysis results showed that the optimal multiplicity of infection was 1.With a burst size of 101 PFU/infected cell,the incubation period was 30 minutes and the out⁃break period was 90 minutes.It was not sensitive to chloroform and could maintain high activity un⁃der the condition of 40-50℃,pH value 4.0-10.0.The genome length of the phage was 168241 bp according to the whole genome sequencing result.With 37.32%of a(G+C)%content,the genomic in⁃cluded 263 ORFs,113 of which were known coding sequences.It contained 2 tRNA,but no lyso⁃genic genes,virulence factors,or antibiotic resistance genes.The whole-genome and phylogenetic tree of the terminase large subunit protein analysis showed that phage vB_EcoM_F2 was closely re⁃lated to Shigella phage phi25-307,but could not infect the standard Shigella sp.strains.At present,the International Committee on Taxonomy of Viruses(ICTV)and the National Center for Biotechnol⁃ogy Information(NCBI)have already classified phage F2 into Myoviridae family,Tevenvirinae sub⁃family,Mosigvirus genus,unclassified Mosigvirus.This study will lay foundation for the application of phage in control of E.coli disease.