Isolation and Characterization of Bacteriophages for Bicontrol of Salmonella and Shiga Toxin-Producing Escherichia coli in Food Applications

Abstract

Salmonella poses a significant risk to public health, with tens of thousands of cases occurring each year. Food is the primary vehicle for Salmonella outbreaks, and several diverse foods are frequently attributed to outbreaks. Traditional methods of pathogen control in the food industry are often indiscriminate, killing microbes that may be beneficial alongside the pathogens. In addition, these methods can alter the organoleptic properties of foods and may not be usable for raw and ready-to-eat foods such as raw poultry or fresh produce. Use of chemical antimicrobials is also growing out of favor in some settings as concerns rise over antimicrobial resistance in foodborne pathogens. Interest is growing in using phage cocktails as an alternative method to combat Salmonella and other foodborne pathogens.Bacteriophages, or phages, are viruses that infect bacteria. They are highly host specific, safe to consume, relatively inexpensive, and do not alter the organoleptic properties of food, making them ideal as a biocontrol agent in a variety of food applications. Using several phages combined in a cocktail can increase their success in killing pathogens and lower the chance of resistance to the phages developing. Phages are the most abundant biological entity on the planet, and most remain undiscovered. A few commercial phage cocktails exist that may be used in the food industry, but identifying novel cocktails of unique phages increases the diversity of the tools available to handle troublesome pathogens that arise. In this study, phages were isolated from local Minnesota wastewater samples. The newly isolated phages were tested for their ability to lyse and kill several serotypes of Salmonella and a few serotypes of Shiga-toxin producing E. coli. Six promising phages were picked for a putative novel cocktail. This putative cocktail was assessed for its ability to reduce Salmonella levels in a raw chicken breast model. The cocktail shows promise as a tool to manage both Salmonella and Shiga-toxin producing E. coli in food and food processing environments.