污水处理系统中肠出血性大肠杆菌O157噬菌体的分离及其生物学特性

Identification and biological property study of an enterohemorrhagic E. coli O157 phage isolated from sewage treatment plant aeration tank

采用双层平板法从污水处理厂曝气池中分离出一株肠出血性大肠杆菌O157强裂解性噬菌体,命名为PO157-Z。通过透射电镜、基因组酶切以及最佳感染复数、裂解曲线和酸碱耐受性等生物学特性测定分析发现:噬菌体PO157-Z头部呈正六面体的立体对称结构,直径约70 nm,尾部较短,长和宽均约10 nm.EcoR I酶切表明,其核酸类型为ds DNA.该噬菌体的最佳感染复数为0.01,其对酸碱耐受性较好,且耐受范围较宽.此外,对宿主菌的裂解曲线进一步表明,其对大肠杆菌O157具有高效快速的裂解作用.因此,PO157-Z作为一株肠出血性大肠杆菌O157强裂解性噬菌体,属ds DNA短尾科噬菌体,其对宿主菌的高效裂解性以及强酸碱耐受性等特点,为污水处理系统中大肠杆菌O157的生物防控,提供了新思路和技术支持.

The purpose of this work was to isolate the lytic phages of Escherichia coli O157 from an aeration tank sample and to investigate the biological characteristics of the isolated phage. The titer of purified bactiriophage was 8. 7 × 10^11 pfu / m L. The electron microscope showed the phage had a hexahedron cubic-symmetric head with 70 nm in diameter and a short tail（ about 10 nm in length and about 10 nm in width）. The restriction enzyme fragments suggested that it was ds DNA. The optimal MOI（ multiplicity of infection） value was 0. 01. Phage PO157-Z showed wide range of acidalkali tolerance. In addition,the curves of bacteria lysed by phage showed that PO157-Z had a highlytic activity on E. coli O157. Thus,PO157-Z is a strain of lytic phage against enterohemorrhagic E.coli O157 and belongs to tailed families Podoviridae with ds DNA. These characteristics of phage PO157-Z would be useful in various applications as a novel biocontrol agent against E. coli O157.