Application of a Phage Cocktail for Control of Salmonella in Foods and Reducing Biofilms

Abstract

<i>Salmonella</i> contamination in foods and their formation of biofilms in food processing facility are the primary bacterial cause of a significant number of foodborne outbreaks and infections. Broad lytic phages are promising alternatives to conventional technologies for pathogen biocontrol in food matrices and reducing biofilms. In this study, 42 <i>Salmonella</i> phages were isolated from environmentally-sourced water samples. We characterized the host range and lytic capacity of phages LPSTLL, LPST94 and LPST153 against <i>Salmonella</i> spp., and all showed a wide host range and broad lytic activity. Electron microscopy analysis indicated that LPSTLL, LPST94, and LPST153 belonged to the family of <i>Siphoviridae</i>, <i>Ackermannviridae</i> and <i>Podoviridae</i>, respectively. We established a phage cocktail containing three phages (LPSTLL, LPST94 and LPST153) that had broad spectrum to lyse diverse <i>Salmonella</i> serovars. A significant decrease was observed in <i>Salmonella</i> with a viable count of 3 log₁₀ CFU in milk and chicken breast at either 25 °C or 4 °C. It was found that treatment with phage cocktail was able to significantly reduced biofilm on a 96-well microplate (44-63%) and on a stainless steel surface (5.23 to 6.42 log₁₀). These findings demonstrated that the phage cocktail described in this study can be potentially used as a biological control agent against <i>Salmonella</i> in food products and also has the effect to reduce <i>Salmonella</i> formed biofilms.