Biocontrol of Salmonella Typhimurium growth in tomato surface by bacteriophage P22

The aim of this research was to evaluate the effect of bacteriophage P22 on Salmonella Typhimurium in artificially inoculated tomato surface, under simulating condition of storage (10°C) and marketing (20°C) during seven days. First, we demonstrated the in vitro ability of phage P22 to reduce host population density to undetectable levels two hours after inoculation; however, S. Typhimurium was able to regrow up to 5.5 Log10CFU/ml after 24 h. S. Typhimurium-inoculated tomatoes stored at 10°C and exposed to P22 exhibited a mean bacterial reduction of 3.02 Log10CFU/tomato, while those stored at 20°C showed a mean reduction of 0.7 Log10CFU/tomato at day seven. Although phage P22 was able to reduce S. Typhimurium on tomato surface, the in vitro results indicate that a larger initial concentration of phages is required in order to ensure sustained inactivation of S. Typhimurium.