LISTERIA MONOCYTOGENES IS ONE OF THE MOST NOTORIOUS FOODBORNE PATHOGENS RESPONSIBLE FOR ANNUAL MULTI-BILLION DOLLAR ECONOMIC LOSSES. IN THE ENVIRONMENT, LISTERIA GROWS IN PLANT-ASSOCIATED BIOFILMS, YET OUR UNDERSTANDING OF THESE BIOFILMS IS POOR. THIS KNOWLEDGE GAP HINDERS OUR ABILITY TO PREVENT LISTERIAL CONTAMINATION OF FRUITS AND VEGETABLES, WHICH IS PROBLEMATIC BECAUSE THE FREQUENCY OF LISTERIOSIS OUTBREAKS CAUSED BY CONTAMINATED PRODUCE HAS BEEN INCREASING. THE OBJECTIVE OF THIS PROJECT IS TO CHARACTERIZE THE COMPOSITION AND FUNCTIONS OF THE EXTRACELLULAR MATRIX OF LISTERIAL BIOFILMS ON PLANTS, AND ELUCIDATE THE MECHANISMS CONTROLLING BIOFILM FORMATION AND DISPERSION. OUR PRELIMINARY DATA INDICATE THAT LISTERIAL BIOFILMS ON PLANT MATTER DIFFER DRASTICALLY FROM THE BIOFILMS FORMED ON NON-PLANT SURFACES. ONE OF THE MAJOR MATRIX COMPONENTS OF LISTERIA-PLANT BIOFILMS, THE EXOPOLYSACCHARIDE, GREATLY INCREASES TOLERANCE OF LISTERIA TO DESICCATION AND DISINFECTANTS, AND MAY CONTRIBUTE TO IMPROVED LISTERIAL SURVIVAL ON CONTAMINATED PRODUCE DURING PROCESSING, TRANSPORTATION AND STORAGE. THE EXOPOLYSACCHARIDE-INDEPENDENT EXTRACELLULAR APPENDAGES OF UNKNOWN ORIGIN MAY PROMOTE ATTACHMENT TO PLANT SURFACES. IN THIS PROJECT, WE WILL DECIPHER HOW EXOPOLYSACCHARIDE IS SYNTHESIZED AND DEGRADED, IDENTIFY COMPOUNDS FROM AQUEOUS WOOD EXTRACTS THAT PREVENT BIOFILM FORMATION, AND ELUCIDATE THEIR MECHANISMS, AND INVESTIGATE EXOPOLYSACCHARIDE-INDEPENDENT EXTRACELLULAR APPENDAGES. AS A RESULT, WE WILL GAIN DEEPER UNDERSTANDING OF THE MECHANISMS ALLOWING LISTERIA TO FORM BIOFILMS ON PLANTS AND LEARN HOW WE CAN PROTECT FRESH PRODUCE FROM THESE BIOFILMS. THIS PROJECT WILL INVOLVE STUDENTS AT VARIOUS LEVELS OF PREPARATION, INCLUDING GRADUATE, UNDERGRADUATE AND POST-DOCTORAL STUDENTS, AS WELL AS HIGH-SCHOOL STUDENTS FROM UNDERREPRESENTED GROUPS. RESULTS OF THIS PROJECT WILL BE BROADLY DISSEMINATED VIA SCIENTIFIC ARTICLES, REVIEWS AND CONFERENCE PRESENTATIONS. IN ADDITION, THE PI AND STUDENTS INVOLVED WILL WRITE PUBLICATIONS FOR THE GENERAL PUBLIC AND PRESENT THE PROJECT RESULTS TO WYOMING RESIDENTS.