WHETHER THROUGH FORMING SANITATION-RESISTANT BIOFILMS OR DEVELOPING ENHANCED TOLERANCE TO ANTIMICROBIALS AND SANITIZERS OR EVEN HEAT, FOODBORNE PATHOGENS ADAPT TO AND SURVIVE THE STRESSES OF FOOD PROCESSING AND SANITATION PROGRAMS, LEADING TO CONSUMER ILLNESSES. CONSEQUENTLY, UNDERSTANDING BACTERIAL PATHOGENS' STRESS TOLERANCE STRATEGIES AND CAPABILITIES FOR COLONIZING PROCESSING ENVIRONMENTS IS CRUCIAL TO DEVELOPING NEW METHODS TO FOIL THEM AND REDUCING THE BURDEN OF FOODBORNE ILLNESS. PREVIOUS RESEARCH INDICATED THAT SEVERAL ISOLATES FROM AN OUTBREAK OF SALMONELLA HEIDELBERG IN POULTRY PRODUCTS HAD INCREASED STRESS TOLERANCE AND THAT THIS WAS ASSOCIATED WITH ENHANCED STRESS TOLERANCE GENE EXPRESSION IN STATIONARY PHASE. I HYPOTHESIZE THAT ENHANCED STRESS TOLERANCE MAY PLAY A KEY ROLE IN OUTBREAKS OF SALMONELLOSIS AND THAT THIS MAY BE DETECTABLE VIA GENE EXPRESSION ANALYSIS UNDER NORMAL GROWTH CONDITIONS. KEY SEROVARS (TYPES) OF SALMONELLA IN THE U.S. INCLUDE SALMONELLA ENTERITIDIS, TYPHIMURIUM, HEIDELBERG, AND AN EMERGING SEROVAR CALLED SALMONELLA I 4,[5],12:I:-. I WILL ASSESS STRESS TOLERANCE IN ISOLATES ASSOCIATED WITH THE 2015 SALMONELLA I 4,[5],12:I:- OUTBREAK ASSOCIATED WITH PORK, THE 2011 SALMONELLA HEIDELBERG OUTBREAK ASSOCIATED WITH KOSHER BROILED CHICKEN LIVERS, AND SALMONELLA TYPHIMURIUM OUTBREAK AND ENTERITIDIS OUTBREAKS (TO BE DETERMINED). I HAVE ALSO COMPILED A LIST OF PREVIOUSLY-SEQUENCED NON-OUTBREAK ISOLATES FOR COMPARISON FOR EACH OF THESE SEROVARS. THE CHOSEN ISOLATES REPRESENT A MIX OF ANTIBIOTIC RESISTANCE CAPACITIES, ALLOWING US TO ALSO DETERMINE IF THERE IS A LINK BETWEEN ANTIBIOTIC RESISTANCE AND STRESS TOLERANCE. THESE ISOLATES WILL BE OBTAINED FROM THE USDA-ARS, WITH WHOM I HAVE A MATERIAL TRANSFER AGREEMENT.TO DETERMINE ISOLATES' STRESS TOLERANCE, WE WILL STUDY TWO KEY PROCESSING STRESSES--SANITIZERS AND HEAT. WE WILL ALSO STUDY HOW WELL THE INDIVIDUAL ISOLATES CAN FORM STRESS-TOLERANT BIOFILMS, AS THIS IS A KEY SURVIVAL MECHANISM FOR BACTERIA. WE WILL STUDY SANITIZER TOLERANCE AND BIOFILM FORMATION AT BOTH ROOM AND REFRIGERATION TEMPERATURE AND WITH HIGH AND LOW ACCESS TO NUTRIENTS, AS THESE ARE SCENARIOS COMMONLY ENCOUNTERED IN FOOD PROCESSING ENVIRONMENTS. WE WILL STUDY HEAT AT 132.8&DEG;F/56&DEG;C, AS THIS IS A LETHAL TEMPERATURE COMMONLY USED TO SCALD POULTRY. WE WILL USE THE METHODS DESCRIBED IN OUR PREVIOUS STUDY. WE PREVIOUSLY FOUND THAT STRESS TOLERANT SALMONELLA HEIDELBERG EXPRESS GENES FOR STRESS TOLERANCE AT HIGHER LEVELS, EVEN UNDER NORMAL, NON-STRESSFUL CONDITIONS. TO DETERMINE IF THIS IS TRUE FOR OTHER SALMONELLA SEROVARS, WE WILL DETERMINE THE GENE EXPRESSION PROFILES OF UP TO 3 STRESS TOLERANT AND 3 STRESS SENSITIVE ISOLATES FROM THE FIRST PART OF THE STUDY USING RNA-SEQUENCING. GENE EXPRESSION PROFILES WILL BE DETERMINED AND COMPARED USING A PREVIOUSLY DESCRIBED METHOD. WE WILL ALSO RUN THE ISOLATES' DNA SEQUENCES (PUBLICLY AVAILABLE) THROUGH THE CENTER FOR GENOMIC EPIDEMIOLOGY'S SUITE OF TOOLS TO COMPARE OVERALL GENETIC SIMILARITY, AS WELL AS PRESENCE OF PLASMIDS AND ANTIBIOTIC RESISTANCE GENES.