大肠埃希菌宽宿主谱噬菌体生物学特性的比较研究

Biological Characteristics of Escherichia coli Bacteriophage f_2 in Comparison with Its Broad Host Range Phage

目的比较研究1株宿主谱发生突变的宽宿主范围噬菌体与其原始野生型单一宿主谱噬菌体株的生物学特性改变，探讨噬菌体识别特异性机制和将噬菌体作为生物消毒剂，应用于环境污水净化的可行性。方法利用大肠埃希菌285菌株自环境污水中筛选到1株具有宽宿主范围的噬菌体，与野生型噬菌体f2比较观察，分析宿主谱改变对噬菌体的生物学特性的影响。结果两噬菌体电镜下形态均为微球形且棱角不明显，但（噬菌体XY）颗粒偶见短尾，大小形态不均一；噬菌体f2和噬菌体XY的抗血清K值分别为30．1和41．5；噬菌体XY与噬菌体f2的相关度较低（K值比〈O．45）；结果显示，噬菌体XY较噬菌体f2具有吸附速率高、潜伏期短、裂解量大的特点；两噬菌体均为约6000bp的单链RNA噬菌体，但宿主谱改变前后它们的RAPD-PCR及RT-PCR差异有统计学意义；噬菌体SY对环境水样本中的大肠埃希菌杀灭率可达到36．75％～56．28％，而噬菌体f2则为19．19％～35．06％（P〈0．01）。结论宽宿主谱噬菌体较噬菌体f2在超微形态、一步生长曲线、抗原性等方面差异均有统计学意义；微生物杀灭效果也明显高于噬菌体f2（P〈O．01）；核酸分析证实其宿主特异性裂解效应已从基因水平发生了变化。

OBJECTIVE Through investigation of the changes in biological characteristics of an E scherichia coli bacteriophage with broad host range, to study the mechanism of phage-host specificity and the bactericidal efficacy on sewage water samples. METHODS In this study, oue strain of E. coli bacteriophages with broad host range was screened from natural environment using the E. coii 285. Then, in order to analyze the difference of biologic effects before and after the host range changed, we made a comparison of biological properties between the phage with broad host range and the phage f2. RESULTS The ultrastructure under electron microscope showed that the two phages were round-shaped particles, but phage XY＇s diameter between 20-90 nm, short-tailed and occasionally visible; the anti-serum K value of phages f2 and XY was 30. 1 and 41. 5, respectively; whereas, between phages XY and f2, there was a low correlativity （K value〈0.45）; comparing phage XY with phage f2, one step-growth test showed that phage XY had a higher adsorption rate, shorter incubation period and a stronger lysis ability; analysis test for nucleic acid revealed that phage XY was a 6000 bp, single-stranded RNA bacteriophage. Significant differences in its specificity of RAPD-PCR and RT-PCR were founded before and after host range changed; treating the sewage water with bacleriophage XY, the germicidal test showed that its cleaning rate of E. coli in water samples from environment could reach 36.75-56.28%, and was obviously higher than phage f2 （P〈0.01）. CONCLUSIONS Comparing phage XY with phage f2, the biological properties （configuration, growth curve and antigenic specificity） have been obviously changed; the phage XY＇s cleaning rate of E. coli is obviously higher than phage f2 （P%0.01）; analysis tesl for nucleic acid indicated that host-specific lytic effect of phage XY has been changed in genie level.