f2噬菌体及其宽噬株的生物学特性比较

目的:探讨和比较一株分离自污水中的宽噬噬菌体与其原始野生型标准噬菌体f2株的生物学特性的差异.方法:①测定宿主范围;②测定裂菌滴度;③噬菌斑形态比较及超微结构观察;④血清中和试验以及血清交叉中和试验;⑤一步生长实验.结果:①宽噬噬菌体株可裂解四种同一属不同种大肠杆菌;②宽噬噬菌斑形态、大小、透明度、边缘界限、中心透明区及晕环针对不同宿主菌发生相应变化;③电镜超微结构显示两噬菌体均为二十面体微球形且棱角不明显,但尾部结构及直径范围存在差异;④中和试验测定宽噬噬菌体及其标准株的抗血清K值分别为41.5及30.0;⑤血清交叉中和试验证实二者在血清学上存在较低相关度;⑥一步生长实验显示宽噬噬菌体较其标准株的潜伏期短,裂解量大.结论:宽噬噬菌体的生物学特性与其标准株存在显著差异,可独立为一个血清型.

Comparison of biological characteristics between bacteriophage f2 and its broad host range phage

AIM: To investigate the difference of biological characteristics between a strain of E.coli bacteriophage with broad host range isolated from sewage and a wild standard strain (phage f 2). METHODS: The host range, bacteriolysis titer and antigenicity were detected, the plaque morphology and their ultrastructural characteristics were identified, and serological neutralization test, serological cross neutralization test as well as one step growth experiment were performed. RESULTS: The strain of E.coli bacteriophage with broad host range could lysis 4 strains of Escherichia coli belonging to the same genus but to different species. The plaque morphology of the phage with broad host range changed in accordance with its different host bacteria. The ultrastructure under electron microscope showed that the broad host range phage was different, to some extent, in size and shape from the wild standard strain. Their antiserum K values were also different and serological cross neutralization test showed that there was little correlation between them. One step growth experiment showed that it had a shorter latent period and higher lysis efficiency than the wild standard strain. CONCLUISON: The biological characteristics of broad host range phage may be significantly different from those of its wild standard strain. Therefore, it can be classified into a new serotype.