Isolation and characterization of Salmonella phages and phage cocktail mediated biocontrol of Salmonella enterica serovar Typhimurium in chicken meat

The consumption of foods contaminated with Salmonella continues to be a serious public health concern that can be controlled by implementation of effective measures like application of lytic bacteriophages. In this study, 21 Salmonella bacteriophages were isolated from sewage samples. On transmission electron microscopy, 15 phages were identified as Myoviridae, 05 phages as Siphoviridae, and 01 phage as Podoviridae. Based on lytic spectrum, 15 phages have very wide while 06 phages wide host range. Before testing in the meat sample, all phages were further screened for sensitivity against S. Typhimurium, the strain frequently prevalent in meat and found sensitive against 22.03-81.36% strain. For testing the efficacy of phages as a biocontrol agent, phage cocktail was applied over raw chicken meat spiked with S. Typhimurium at 25 degrees C and 4 degrees C. At MOI of 100, 1000, and 10000 a significant reduction of 1.17, 1.26, and 1.31 log(10) CFU/g in the viable count of S. Typhimurium was observed at 7 h post phage application, in comparison to phage-free controls. However, at 4 degrees C a significant reduction of 1.29, 1.91, 2.48 log(10) CFU/g was achieved after 7 days of incubation. This work intimidates the use of phages for biocontrol of S. Typhimurium in chicken meat.