<i>In-vitro</i> evaluation and efficacy of bacteriophage isolated from commercial poultry farms against <i>Salmonella typhimurium</i>.

Avian Salmonellosis impacts the economy and public health, with chicken products being a major cause of gastroenteritis. Hygiene, immunization and medicines are all used as control techniques. Bacteriophages provide a safe, targeted alternative. In the present study <i>in vitro</i> evaluation of bacteriophages were done against <i>Salmonella typhimurium</i>. Lytic effect of bacteriophages isolated from poultry sludge was checked on culture of <i>S. typhimurium</i>. Stability study was checked at range of temperature and pH. The phages were stable at temperature (30.00 - 50.00 ˚C) and pH (5.00 - 9.00) where best activity was seen at 37.00 ˚C and pH 7.00. <i>In vitro</i> lytic activity was done at (optical density 600 nm) after exposure to bacterial host at different intervals. Multiplicity of Infection of 1.00 was used to check lytic activity of phages which indicated phages were potent enough to infect bacterial cells within their growth cycle. The percentage of unadsorbed phages was determined by bar chart analysis. The genome of three phages was treated with DNase I where they all were sensitive. Later the nucleic acid of phages was digested by restriction endonucleases (<i>EcoRI</i> and HindIII) both of the enzymes produced various restriction sites with different band. The present study proved that the application of bacteriophages <i>in vitro</i> into bacterial system <i>i.e.,</i> <i>S. typhimurium</i> was an attractive method in diminishing infection in commercial poultry thus providing exceptional results that could be used on a large scale.