| Summary: | <p>Abstract</p> <p>Background</p> <p>Despite the proven relevance of <it>Pseudomonas fluorescens </it>as a spoilage microorganism in milk, fresh meats and refrigerated food products and the recognized potential of bacteriophages as sanitation agents, so far no phages specific for <it>P. fluorescens </it>isolates from dairy industry have been closely characterized in view of their lytic efficiency. Here we describe the isolation and characterization of a lytic phage capable to infect a variety of <it>P. fluorescens </it>strains isolated from Portuguese and United States dairy industries.</p> <p>Results</p> <p>Several phages were isolated which showed a different host spectrum and efficiency of lysis. One of the phages, phage ϕIBB-PF7A, was studied in detail due to its efficient lysis of a wide spectrum of <it>P. fluorescens </it>strains and ribotypes. Phage ϕIBB-PF7A with a head diameter of about 63 nm and a tail size of about 13 × 8 nm belongs morphologically to the <it>Podoviridae </it>family and resembles a typical T7-like phage, as analyzed by transmission electron microscopy (TEM). The phage growth cycle with a detected latent period of 15 min, an eclipse period of 10 min, a burst size of 153 plaque forming units per infected cell, its genome size of approximately 42 kbp, and the size and N-terminal sequence of one of the protein bands, which gave similarity to the major capsid protein 10A, are consistent with this classification.</p> <p>Conclusion</p> <p>The isolated T7-like phage, phage ϕIBB-PF7A, is fast and efficient in lysing different <it>P. fluorescens </it>strains and may be a good candidate to be used as a sanitation agent to control the prevalence of spoilage causing <it>P. fluorescens </it>strains in dairy and food related environments.</p>
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