鸡致病性大肠杆菌的质粒DNA指纹图谱分析

从山东省诸城地区6个集约化养鸡场的大肠杆菌感染鸡群的死鸡、毛蛋的心血中分离到32株细菌,经形态、培养特性及生化反应鉴定为大肠埃希氏杆菌(Escherichia.coli)简称大肠杆菌(E.coli)。对其作动物回归试验结果表明,全部为致病性大肠杆菌。从而证明从死鸡(毛蛋)心血中分离到的大肠杆菌与其致病性密切相关。将分离到的鸡大肠杆菌的14株优势血清型菌株进行了质粒DNA分析,通过碱裂解法小量提取质粒,然后对质粒进行了琼脂糖凝胶电泳分析,用hindⅢ限制性内切酶对质粒进行了酶切分析,结果表明:质粒的得率为100%,来源相同的菌株具有相同或相似的质粒图谱,来源不同的菌株的质粒图谱一般不同。将血清型和质粒图谱比较发现:同一血清型可以有不同的质粒图谱,不同血清型可以有相似的质粒图谱,血清型与质粒图谱没有直接的联系。本试验同一来源菌株的质粒指纹图谱相同、但它们的血清型不一致的现象可作为自然条件下同一质粒在不同血清型大肠杆菌中扩散转化的一个分子生物学依据。

PLASMID PROFILE ANALYSIS ON PATHOGENIC E COLI FROM CHICKENS

Thirty-Two strains of Escherichia coli(E.coli) had been isolated from heart blood specimens of E.coli infected chickens in six farms in Shandong zhucheng Foreign Trade Group Corp.All of them were examined for pathogenicity in susceptible chickens inoculated.All strains of E.coli isolated from blood specimens were proved to be virulent.In the screening test of plasmid DNA from 14 strains of E.coli isolates and plasmid DNA fragments generated by restrtctton endo-nuclease Bamhi,simple agarose gel electrophoresis was employed.Results showed that most of E.coli isolates from the same infected flocks on the same farm had similar plasmid profile,and its fragments sizes were similar too,and that these isolates had common plasmids.Results!showed!that those isolates which isolated from different flocks of chicken and had different plasmids were in different serotypes,This confirmed that plasmids could be transfered in different serotypes of E.coli