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The primary goal of proposed research is to utilize fundamental and applied research to gain understanding of bacterial foodborne pathogen adhesion to produce surfaces and the forces required to inhibit pathogen adherence to produce. Studies will result in development of novel multifunctional intervention strategies to prevent pathogen adherence and/or facilitate produce surface decontamination via delivery of nano-encapsulated food antimicrobial.<P> Project-specific goals are to: 1) elucidate the factors critical to foodborne pathogen attachment to produce surfaces; 2) quantify the impact of background microbiota on pathogen adherence; 3) develop and apply nano-encapsulated plant-derived food antimicrobial for decontamination of produce and prevention of pathogen adherence; and 4) ultimately to significantly enhance the safety of fresh and minimally processed produce safety by understanding of factors affecting pathogen adherence and produce decontamination. <P>Objective 1: Characterize intermolecular and surface forces controlling bacterial adhesion on produce. Determine proportional contributions of Brownian motion, Van der Waals attraction forces, ionic and dipole interactions, gravitational forces, surface electrostatic charge distribution, capillary and hydrophobic interactions to bacterial adhesion on produce surfaces. Construct kinetics model of bacterial adhesion to produce and determine temperature, pathogen concentration, outer membrane hydrophobicity, surface charge, substrate surface tension, composition, and topography influences on bacterial adsorption to produce surfaces.<P> Objective 2: Determine the roles played by background microbiota in the attachment and transmission of enteric bacterial pathogens to produce surfaces with differing characteristics. Identify classes of microbes (lactic acid bacteria, fungi, epiphytics) and levels of each that antagonize pathogen adherence to produce surfaces.<P>Objective 3: Develop and characterize physico-chemical and antimicrobial properties of novel food polymer coating strategies with nano-entrapped antimicrobial to reduce bacterial adhesion and increase bacterial lubrication on produce surfaces, thus preventing attachment or facilitating inhibition of produce-contaminating pathogens. <P>Project Outputs: Identification and quantification of surface properties of produce commodities influencing bacterial attachment and adhesion. Elucidation of the roles of background microbiota in the cross-contamination of produce by pathogens. Determination of the roles of background microbiota antagonizing pathogens and contributions of background microbiota to the protection of pathogen inhibition. Development and optimization of antimicrobial encapsulates applied for the generation of multi-functional antimicrobial/antifouling polymers. <P>These studies will generate data elucidating the impacts of produce physiology, processing, and intervention usage on the inhibition of pathogen growth on surfaces and attachment. Ultimately, novel interventions will be designed and validated for efficacy through these and previous studies for use in produce processing to control pathogen attachment and adherence.
Non-Technical Summary: The microbiological safety of fresh and minimally processed produce is challenged by the cross contamination of multiple foodborne microbial pathogens that are ultimately transmitted to the consumer. Additionally, the threat of foodborne disease is heightened because these produce items are not subjected to any type of pathogen inactivating intervention except some surface washing processes which are considered by many to be only moderately effective. However, greater understanding of the forces that influence the ability of microbial pathogens to attach to produce surfaces following contamination would assist scientists in efforts to develop novel strategies to decontaminate produce surfaces either prior to harvest or in the processing facility. The impacts of described research may result in the development of food safety interventions capable of delivering effective food antimicrobials to sites on produce surfaces likely to harbor foodborne pathogens, thereby reducing the numbers of contaminating pathogens transmitted to the consumer and enhancing other interventions applied by produce processors. It is anticipated also that produce safety and microbiological quality will be enhanced by the application of derived antimicrobial delivery technologies, as non-pathogenic microbes capable of produce spoilage will also likely be inhibited, increasing produce shelf-stability and inherent value. <P> Approach: Fundamental and applied microscopic, physico-chemical, and microbiological analyses will be completed in order to complete listed project objectives. Use of multiple microscopic and physico-chemical assays will provide understanding of bacterial adhesion and attachment processes on differing produce surfaces, completing objective 1. Objective 2 will utilize microbiological and microscopic methods to determine the types, numbers, and locations on produce where differing background microbes preferentially locate and attach, removing potential colonization sites available to pathogens. Analysis of metabolic products from background microbes will further assist in understanding their respective roles in inhibition of pathogen contamination. Objectives 3 and 4 will ultimately be accomplished by series of microbiological and physicochemical assay, constructing and quantifying the properties of food antimicrobial bearing nano-encapsulate structures. These structures will be subjected to multiple physico-chemical and rheological analysis tools in addition to microbiological testing designed to determine their antimicrobial efficacy. Data gathered will be statistically analyzed for the identification of significant forces contributing to microbial adherence to produce surfaces, forces antagonizing pathogen attachment, and efficacy of antimicrobial delivery nanosystems contributing to the reduction of contaminating pathogens. These data will be presented at relevant scientific meetings designed to disseminate data to other scientists, industry and government officers, and published in scientific and non-refereed formats in order to broadcast findings to scientists and laymen.