A method for the direct isolation of IncH plasmid-dependent bacteriophages

A method is described for the isolation of IncH plasmid-dependent bacteriophages present in very low numbers in sewage. An isogenic plasmid-lacking host was used to absorb the majority of non-specific phages. This resulted in an enrichment of 100-to 400-fold of the IncH-dependent phages. A total of 27 IncH-dependent phages were isolated and all were shown to be temperature-sensitive RNA phages which produced turbid plaques.