Abstract:

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.

Key words: bacteriophages, Enterobacter cloacae, drug-resistant bacteria