A bacteriophage was isolated from the swine lagoon by the double layer plaque assay using S. Typhimurium ATCC 13311 as a host strain. The bacteriophage produced clear plaques on the lawn of the host strain, indicating that it was a virulent (or lytic) bacteriophage. The plaques were small with an average diameter of 1 mm (Fig. 1a), and the isolated bacteriophage was designated ST1.