一株产肠毒素大肠杆菌短尾噬菌体分离与鉴定

Isolation and identification of an enterotoxigenic E.coli Podoviridae phage

以产肠毒素大肠杆菌(Enterotoxigenic Escherichia coli,ETEC)K88为宿主菌,从养殖场污水中分离出一株短尾裂解性噬菌体vB_EcoP_E21。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0.1,潜伏期和爆发期均为20 min,裂解量为370 PFU·cell-1;对氯仿不敏感,可在40~60℃,pH 4.0~10.0条件下保持较高活性;全基因组测序结果表明其基因组长度为58536 bp,(G+C)%含量为46.89%,含66个开放阅读框,其中23个为已知编码序列;不含tRNA、溶源基因、毒力因子和抗生素耐药基因;噬菌体终末端酶大亚基和主要衣壳蛋白系统发育树同源性分析结果显示,该大肠杆菌噬菌体与变形杆菌(Proteus)噬菌体P16-2532、PM87、pPM 01和Saba亲缘关系较近,但无法侵染变形杆菌属(Proteus spp.)标准菌株。

Using an enterotoxigenic Escherichia coli(ETEC)K88 as the host strain,a Podoviridae lytic phage,vB_EcoP_E21,was isolated from the farm sewage.Phage vB_EcoP_E21 had a broad host range,which could infect mostly test strains of E.coli.The general characteristic analysis results showed that the optimal multiplicity of infection was 0.1.With a burst size of 370 PFU·cell-1,the incubation period and the outbreak period were 20 min,respectively.It was not sensitive to chloroform and could maintain high activity under the condition of 40-60℃,pH 4.0-10.0.The genome length of this phage was 58536 bp according to the whole genome sequencing result.With 46.89%of a(G+C)%content,the genomic included 66 ORFs,23 of which were known coding sequences.It did not contain tRNA,lysogenic genes,virulence factors,or antibiotic resistance genes.Based on the terminase large subunit and capsid protein,phage vB_EcoP_E21 was closely related to Proteus phages P16-2532,PM87,pPM01,Saba,but could not infect the standard Proteus spp.strains.