** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** NECROTIC ENTERITIS (NE), CAUSED BYCLOSTRIDIUM PERFRINGENS, IS COSTING THE GLOBAL POULTRY INDUSTRY $6 BILLION ANNUALLY. WITH NO CURRENT EFFECTIVE MITIGATION STRATEGIES, IT IS IMPERATIVE TO DEVELOP NOVEL ANTIBIOTIC ALTERNATIVE SOLUTIONS. OUR LAB HAS BEEN INVESTIGATING THE ROLE OF COMMENSAL BACTERIA IN MEDIATING COLONIZATION RESISTANCE AGAINST NE. FOLLOWING A RECENT SCREENING OF A LIBRARY OF INTESTINAL BACTERIA, WE IDENTIFIED A GRAM-NEGATIVE COMMENSAL BACTERIUM WITH A ROBUST CAPACITY TO INHIBITC. PERFRINGENSGROWTH AND ENHANCE INNATE IMMUNITY BY STIMULATING THE SYNTHESIS OF HOST DEFENSE PEPTIDES (HDP). IMPORTANTLY, ORAL ADMINISTRATION OF THE BACTERIUM PROVIDED SIGNIFICANT PROTECTION TO CHICKENS AGAINST NE, IMPLYING ITS POTENTIAL FOR NE MITIGATION. THE OVERALL GOAL OF THIS PROJECT IS TO REVEAL THE MAJOR ANTIBACTERIAL AND IMMUNE-BOOSTING METABOLITES PRODUCED BY THE BACTERIUM AND THEIR MECHANISMS OF ACTION IN RESISTING NE. WE HYPOTHESIZE THAT THE COMMENSAL BACTERIUM PRODUCES ANTIMICROBIAL METABOLITES AND MODULATES INTESTINAL MICROBIOTA, MUCOSAL IMMUNITY, AND BARRIER INTEGRITY TO LIMIT THE COLONIZATION OFC. PERFRINGENS. TWO OBJECTIVES ARE PROPOSED: 1) IDENTIFY MAJOR ANTIBACTERIAL AND HDP-INDUCING METABOLITES AND 2) ELUCIDATE THE MECHANISMS BY WHICH MAJOR METABOLITES RESIST C. PERFRINGENS BOTHIN VITROANDIN VIVO. UPON PROJECT COMPLETION, SEVERAL METABOLITES ARE EXPECTED TO BE IDENTIFIED WITH POTENT ANTI-C. PERFRINGENSAND HDP-INDUCING ACTIVITIES. ADDITIONALLY, THE METABOLITES ARE ANTICIPATED TO ACCELERATE THE MATURATION OF THE INTESTINAL MICROBIOTA, STRENGTHEN BARRIER FUNCTION, AND ENHANCE MUCOSAL IMMUNITY. THE OUTCOMES WILL FACILITATE THE DEVELOPMENT OF THE COMMENSAL BACTERIUM AND ITS METABOLITES AS A NOVEL STRATEGY AGAINST NE. IMPORTANTLY, THE PROJECT WILL SUPPORT AN UP-AND-COMING SCIENTIST AS SHE PURSUES A CAREER IN ANIMAL HEALTH RESEARCH.