奶牛乳房炎源大肠埃希氏菌噬菌体的分离与生物学特性分析

Isolation and Characterization of a Lytic Phage Infecting Escherichia coli from Cow Mastitis

以实验室保存的奶牛乳房炎源大肠埃希氏菌为宿主菌,从石河子大学试验站奶牛圈舍内的污水中分离纯化到一株大肠埃希氏菌噬菌体,对其进行生物学特性分析。利用双层琼脂平板法分离纯化噬菌体,对噬菌体进行噬菌斑及电镜观察,测定其裂解率、核酸类型、最佳感染复数、一步生长曲线、热稳定性和酸碱稳定性。结果表明,该噬菌体形成的噬菌斑透亮、近似圆形,直径约2.2 mm~2.4 mm;电镜观察发现该噬菌体的头部大小约63.4 nm×65.2 nm,尾部大小约114.4 nm×18.6 nm,形态与肌尾噬菌体相似,将其命名为vB-EcoC-P17(简称P17);其对大肠埃希氏菌的裂解率为30.00%(6/20),核酸类型为dsDNA;最佳感染复数为0.1,裂解量约为17PFU/cell,暴发期约130 min;在pH5.0~11.0时活性稳定,能耐受60℃左右高温。表明噬菌体P17是一株对不同温度、不同酸碱性环境有较强适应能力的裂解性肌尾科大肠埃希氏菌噬菌体,为奶牛乳房炎的噬菌体防治提供了生物学材料。

Using the laboratory isolated dairy cow mastitis-derived Escherichia coli as host bacteria, a Escherichia coli phage was isolated and purified from the wastewater of dairy cow in Shihezi University.The biological characteristics of E.coli phage were analyzed.The phage was isolated and purified by double agar plate method.Its morphology was observed by plaque and transmission electron microscope.The nucleic acid type, optimal multiplicity of infection, Cracking rate, one-step growth curve, thermal stability and acid-base stability were determined.The plaque was transparent and approximately round, with a diameter of about 2.2 mm-2.4 mm, electron microscope observation revealed that the head size of the phage was about 63.4 nm×65.2 nm, and the tail length was about 114.4 nm×18.6 nm.The morphology of the phage was similar to that of the Myophage,named vB-EcoM-P17(P17 for short).For E.coli,the cleavage rate 30.00%(6/20),the nucleic acid type was dsDNA.The optimal multiplicity of infection was 0.1,the burst size was about 17 PFU/cell, and the outbreak period was as long as 130 min.The activity was stable under pH5.0-11.0,and it could withstand high temperature of 60℃.Phage P17 belongs to lytic phage of Myoviridae, which showed strong capacity to adapt different environment conditions such as temperatures and acid-base values.It provided biological material for phage control of cow mastitis.