Reducing the contamination of milk and produce using bacteriophage

Investigator: Bruce Applegate (Department of Food Science)

Project Report 2012 - 2013

Fresh produce and raw milk have been linked to a series of foodborne illness outbreaks. Bacteriophages have a history of use as antibacterial agents and for treating bacterial infections. They function by binding to specific receptor sites on the surface of bacteria, and some then lyse (break open) the target bacteria. This creates the possibility of developing bacteriophage treatments to reduce food contamination if bacteriophages specific to foodborne pathogens are selected. ARS-funded researchers at Purdue University's Center for Food Safety Engineering in West Lafayette, Indiana, have been working with bacteriophages to develop food safety applications. These efforts have resulted in the development of a luminescent phage-based detection system for foodborne pathogens in milk that also reduces the pathogens. More importantly the data suggest the potential for phage use in the control of spoilage organisms either by addition post-pasteurization or in an active packaging format. In another application, bacteriophages have the potential to reduce seed contamination. Because most produce is grown outdoors, it is vulnerable to contamination from pathogens that may be present in the surrounding soil or water, in manure used as fertilizer, or due to the presence of animals in or near fields. These pathogens may enter plants during germination. Once the plant is colonized with a pathogen, whether on the surface or internally, post-harvest disinfection may prove inadequate for making that plant safe for consumption. Use of bacteriophages as seed coatings could be an effective and inexpensive strategy to prevent this initial contamination. Center for Food Safety Engineering scientists used a commercial polymer to encapsulate, concentrate, and reduce loss of activity of bacteriophage on seed surfaces, resulting in the development of a promising approach for reducing preharvest contamination of produce. Applications such as these further demonstrate the broad and powerful potential for adapting naturally-occurring bacteriophages for the purpose of making our food supply safer.

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