** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THIS PROPOSAL ALIGNS WITH THE PROGRAM FOCUSED ON METHODS TO MONITOR AND UNDERSTAND THE DISPERSAL OF GE ORGANISMS AND INVESTIGATES THE SURVIVAL AND FITNESS OF THE GE ORGANISMS COMPARED TO THE NON-GE COUNTERPART ACROSS DIFFERENT ENVIRONMENTS AND HOSTS. WITH TOOLS FOR GENOME ENGINEERING AND ADVANCES IN SYNTHETIC BIOLOGY, ATTEMPTS HAVE BEEN MADE TO ENGINEER BETTER PROBIOTICS WITH DESIRED CHARACTERISTICS AND FUNCTIONALITIES. SUCH PROBIOTICS WITH ENHANCED FUNCTIONAL FEATURES CAN BE USED TO IMPROVE ANIMAL HEALTH AND PRODUCTIVITY AS MICROBES PLAY AN IMPORTANT ROLE IN NUTRIENT UTILIZATION AND IMMUNE MODULATION. TO DATE, SYSTEMATIC ANALYSIS OF FEEDING GENETICALLY ENGINEERED MICROORGANISMS TO LIVESTOCK AND HOW ENGINEERED MICROBES PERSIST, INTEGRATE, AND STABILIZE WITHIN THE GUT MICROBIOME AND ASSOCIATED ENVIRONMENTS IN THE SHORT AND LONG TERM HAS NOT BEEN PERFORMED. THE PROPOSED EXPERIMENTS WILL DIRECTLY ADDRESS THIS KNOWLEDGE GAP BY 1) EXAMINING ECOLOGICAL CHANGES IN THE ANIMAL'S FECAL AND ORAL MICROBIOME IN RESPONSE TO FEEDING A GENETICALLY ENGINEERED ORGANISM; 2) EVALUATE CHANGES IN ENVIRONMENTAL MICROBIOMES ASSOCIATED WITH SOIL; 3) EVALUATE LONG AND SHORT-TERM STABILITY AND PERSISTENCE OF THE GENETICALLY ENGINEERED MICROBE IN THE ANIMAL GUT AND GENE FLOW TO OTHER MICROBES; 4) TRANSMISSION OF THE GENETICALLY ENGINEERED MICROBE BETWEEN ANIMALS. AS SUCH, THIS STUDY WILL DEVELOP CRITICAL AND TIMELY INFORMATION TO HELP EVALUATE THE LONG AND SHORT-TERM RISKS ASSOCIATED WITH UTILIZING GENETICALLY ENGINEERED MICROBES IN LIVESTOCK PRODUCTION AND WILL HELP REGULATORY AGENCIES MAKE SCIENCE-BASED INFORMED DECISIONS ON UTILIZING GENETICALLY ENGINEERED MICROBES IN LIVESTOCK PRODUCTION.