Role of Protozoan Cysts in Protecting Pathogens of the Fresh Produce Industry

The overarching goal of the project is to determine whether protozoa isolated from produce can be induced to form cysts and trapfoodborne pathogenic bacteria in the presence of sanitizers and modified atmosphere packaging (MAP) conditions used in the packaging of fresh produce. We have partnered with TaylorFarms in Smyrna, TN to obtain the produce, sanitizer, packaging material, and MAP conditions for this study.The majorobjectives in achieving this end are to: 1) Isolate and culture cyst-forming protozoa from produce to use in the study; 2) Test sequestration of E. coli O157:H7, Listeria, and Salmonella in cysts of amoebae and ciliates isolated from produce; 3) Determine whether MAP and sanitizers (chlorine and T-128 from Taylor Farms) can induce protozoa to encyst,thereby trapping and protecting pathogens; 4) Test release of viable foodborne pathogens from protozoan cysts after sanitizer and MAP treatment; and 5) Compare inner and outer leaves ofproduce for protozoan populations using next generation sequencing. Knowing how the protozoannumbers anddiversitydiffer on different ages of leaves will be helpful for understanding the distribution of potential cyst-forming protists and their interactions. We will also determine the protozoan microbiome in the industry water used to wash produce as an additional source of protozoa on the packaged produce.Theseobjectives will help to determine the significance of and roles for protozoa in outbreaks associated with packaged produce, such that understanding the roles for these organisms may lead to newinterventions for reducing protozoa on produce, thereby reducing the risk for foodborne illness related to produce.