兔源大肠埃希菌噬菌体分离鉴定与生物学特性研究

对浙江省某兔场腹泻病兔进行病原分离鉴定,经革兰氏染色和PCR鉴定,分离出致病性大肠埃希菌1株,命名为ZJE1株。ZJE1株对链霉素、环丙沙星敏感。以ZJE1株为宿主菌,分离纯化出噬菌体4株,分别命名为ZRP2、ZRP3、ZRP4和ZRP5,并对其生物学特性、形态与结构特征进行研究。结果显示,4株噬菌体分离株均由六角形的头部、可收缩的尾鞘和尾管组成,均属于肌尾噬菌体科。采用双层平板法测定噬菌体分离株的宿主谱、最佳感染复数、pH稳定性、热稳定性和一步生长曲线。结果显示,ZRP2、ZRP3、ZRP4和ZRP5具有宿主特异性,在37~55 ℃的条件下可保持良好活性。ZRP2、ZRP3在pH值7的条件下可保持良好活性,ZRP4、ZRP5在pH值5~7的条件下可保持良好活性。ZRP2、ZRP3、ZRP5的潜伏期为11~19 min,均能在体外裂解ZJE1株。研究成果可为应用噬菌体治疗兔大肠埃希菌病提供研究基础与数据支持。

Isolation,identification and biological characteristics of rabbit-derived Escherichia coli bacteriophage

In this study, one enteropathogenic Escherichia coli strain was isolated and identified via Gram staining and PCR from a rabbit farm in Zhejiang Province, China, which was named as ZJE1. ZJE1 was sensitive to streptomycin and ciprofloxacin. Four bacteriophages were isolated with the ZJE1 strain, which were named as ZRP2, ZRP3, ZRP4 and ZRP5, respectively. The biological and morphological characteristics of these bacteriophages were analyzed. It was shown that the bacteriophages were composed of hexagonal head, contractible tail sheath and tail tube. All the four bacteriophages belonged to Myoviridae family. The host spectrum, optimal multiplicity of infection (MOI), pH stability, thermal stability and one-step growth curve of these four bacteriophages were determined by double-layer plate method. The results showed that ZRP2, ZRP3, ZRP4 and ZRP5 all showed good activity under 37-55 ℃ with high host specificity. ZRP2, ZRP3 could maintain good activity under pH value of 7, while ZRP4 and ZRP5 could maintain good activity under pH value of 5-7. ZRP2, ZRP3, ZRP5 showed good lytic activity in vitro, with incubation period of 11-19 min. These findings provided research basis for the treatment of rabbit enteropathogenic E. coli with bacteriophage.