2株可感染大肠埃希菌工程菌的噬菌体的鉴定与分析

Identification & Analysis of Two Escherichia coli Infectable Phage Strains

大肠埃希菌来源的基因工程菌是应用最为频繁的工程菌,但在基因工程菌规模化制备生物活性制剂的过程中常常会被噬菌体感染。通过对鸡粪中噬菌体大量筛选及鉴定,对工程菌防御相应噬菌体感染机制开展基础研究。实验以大肠埃希菌工程菌为宿主菌（CICC编号：10424）,采用双层琼脂平板法从鸡场粪样中分离噬菌体,结果获得2株噬菌体,对其进行形态学鉴定。经透射电镜观察发现一株（CX）为短尾噬菌体,其头部外廓呈长六角形,非收缩性尾部,其噬菌斑清晰透亮,周围无晕环,裂解性较强;另一株（B1X）为长尾科噬菌体,其噬菌斑呈双层环状,中心澄清透明,直径约0.8-1.3 mm,外环呈半透明,云雾状区域,宽约0.8-1.3mm。可进一步研究这2株噬菌体的侵染机制。

Genetic engineering bacteria （GEB） bred fi＇om E. coli is fi＇equently used GEB. However, bacteriophage infection is a commom for culturing GEB in large-scale during the process of bio-aetive preparation. By screening and identifying phages by the gross from chicken manure, so as to carry out some basic studies on relevant phage infection mechanisms for the GEB defense. In this experiment, isolation method of double layer agar plate was used to separate the phages from chicken manure samples and an E. coli engineering bacteria （CICC code： 10424） was used as a host bacterium tbr phage isolation. As a result two phage strains were isolated and identified their morphologies. The ima- ges of transmission electron microscopy revealed that one strain （CX） is a Podoviridae phage that with a hexagonal head and a non-contractile tail. Its plaque was clear and transparent, without halo around, and with strong splitting character. Another strain （B1X） is a Siphoviridae phage that could form plaques （0.8 - 1.2 mm in diameter） pres- ent a double ring with a limpid center surrounded by a translucent loop （0.8 - 1.3 mm in diameter）. It might be a phage with moving capability. The infection mechanism of these two phages can be further studied.