Isolation and identification of Enterobacter cloacae bacteriophages ФEc53

Objective To isolate bacteriophages from raw sewage and to investigate the biological properties of bacteriophages using 14 strains of Enterobacter cloacae as host cells,and to identify its structure.Methods Bacteriophages were isolated from sewage with double-agar and identified by plaque method.After purification and negative-staining of bacteriophages,the morphologic features of bacteriophages were examined by electron microscope,the bacteriophage genome was extracted for electrophoresis;the lytic spectrum of host was carried out for specificity and cracking range of the Enterobacter cloacae.Results Bacteriophage ФEc53 was isolated and identified,electron micrograph showed that the head of bacteriophage was spherical,60 nm in diameter and it had a tail,about 130 nm long.Electrophoresis of phage DNA revealed that the size of genome was about 40 000 bp and contained lots of restriction sites.The lytic spectrum trial showed it had a relatively narrow host range.Conclusion The isolated Enterobacter cloacae(named ФEc53) bacteriophage belongs to Caudovirales,Siphoviridae.According to its biologic features,bacteriophage ФEc53 has strong lytic and high specificity.