Isolation, classification and molecular characterization of bacteriophages for Enterobacter species

Out of 22 Enterobacter phages investigated, nine were found to be suitable for phage typing based on their different lytic spectra on 398 strains of Enterobacter spp. isolated from milk powder and other foods. These phages were compared on the basis of morphology, protein composition, restriction endonuclease patterns and DNA-DNA hybridization. Two phages (WS-EP19, WS-EP13) belonged to the Podoviridae family (morphotype C1), and three (WS-EP20, WS-EP26, WS-EP28) were classified as Siphoviridae (morphotype B1). The other four phages were Myoviridae of the morphological groups A1 (WS-EP57) and A2 (WS-EP32, WS-EP94, WS-EP96). SDS-PAGE revealed individual protein profiles for each phage, which corresponded to different restriction enzyme fragment patterns. DNA-DNA hybridization demonstrated the close relationship of phages WS-EP20 and WS-EP26, and of WS-EP94 and WS-EP96. In general, a good correlation was found between groupings obtained with the various methods. The nine phages could be attributed to existing enterobacterial phage species although some differences to the described type phages were observed.