Water samples used as sources of bacteriophage specific to S. Typhimurium were
collected from swine lagoon in Ubon Ratchathani province, Thailand. For bacteriophage isolation, each water sample of about 10 ml was prepared as follows. The sample was centrifuged at 4,500 xg for 15 min to precipitate cell debris.The supernatant was filtered through a 0.45-ìm pore-size membrane filter. The filtrate of 4.9 ml and 0.1 ml of log phase S. Typhimurium culture were added to 5 ml of double strength BHI (2X BHI) broth. The mixture was mixed thoroughly and incubated at 37°C for 24 h. At the end of incubation period, the suspension was
centrifuged at 4,500 xg for 15 min and the supernatant was filtered through a 0.45-ìm pore size membrane filter.