Biocontrol of Salmonella Typhimurium in RTE foods with the virulent bacteriophage FO1-E2

Foodborne Salmonella infections are a major public health concern worldwide. Bacteriophages offer highly specific and effective biocontrol of such pathogens. We evaluated the broad host range, virulent phage FO1-E2 for reduction of Salmonella Typhimurium in different RTE foods. Samples were spiked with 1 × 103Salmonella cells and treated with 3 × 108 pfu/g phage, and incubated for 6 days at 8 °C or 15 °C. At 8 °C, no viable cells remained following FO1-E2 application, corresponding to a more than 3 log10 unit reduction. At 15 °C, application of phage lowered S. Typhimurium counts by 5 log units on turkey deli meat and in chocolate milk, and by 3 logs on hot dogs and in seafood. In egg yolk, an effect was observed only after 2 days, but not after 6 days. Phage particles retained their infectivity, although they were readily immobilized by the food matrix, resulting in loss of their ability to diffuse and infect target cells. At the end of the incubation period, phage-resistant Salmonella strains appeared which, however, were not able to compensate for the initial killing effect. Altogether, our data show that virulent phages such as FO1-E2 offer an effective biocontrol measure for Salmonella in foods.

► Salmonella biocontrol efficacy of bacteriophage FO1-E2 was evaluated.
► At 8 °C storage temperature, no viable bacteria were detected after treatment.
► At 15 °C storage temperature, Salmonella growth was suppressed by at least 2 and up to 5 log units on different foods.
► Phage particles were stable and retained infectivity.
► Bacteriophage FO1-E2 is an effective biocontrol agent for Salmonella.