** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THE UNPRECEDENTED GLOBAL WATER CRISIS DUE TO POPULATION GROWTH AND CLIMATE CHANGE IS BEING RESOLVED USING RECLAIMED WASTEWATER (RWW) FOR IRRIGATION AND TO RECHARGE GROUND WATER SUPPLIES. HOWEVER, EVEN AFTER EXTENSIVE TREATMENT RWW CONTAINS CONTAMINANTS OF EMERGING CONCERN (CECS) SUCH AS PERSONAL CARE PRODUCTS AND HUMAN AND VETERINARY PHARMACEUTICALS. THEREFORE, USE OF RWW FOR IRRIGATION CONTINUOUSLY ADDS CECS TO AGRICULTURAL SOILS. CECS ACCUMULATE IN SOIL AND PLANTS, AND HAVE THE POTENTIAL TO CHANGE SOIL PROPERTIES AND CAUSE PLANT STRESS. CECS HAVE BEEN SHOWN TO ALTER INSECT GUT AND SOIL BACTERIAL POPULATIONS. PLANTS FORM INTRICATE RELATIONSHIPS WITH THE SOIL MICROBES, WHICH IMPROVES PLANT FITNESS AND FUNCTIONING UNDER VARIOUS ENVIRONMENTAL STRESS CONDITIONS. MOST LEGAL GUIDELINES FOR RWW IN MANY COUNTRIES REQUIRE EVALUATION FOR HUMAN PATHOGENS AND SOIL PHYSICOCHEMICAL FACTORS (E.G. PH, SALINITY, HEAVY METAL) TO PREVENT RISKS TO HUMAN HEALTH AND MAJOR CHANGES IN SOIL PROPERTIES. HOWEVER, OTHER EQUALLY IMPORTANT DETERMINANTS OF SOIL AND PLANT HEALTH (E.G., SOIL MICROBIOME) ARE NOT CONSIDERED. PLANTS FORM COMPLEX RELATIONSHIPS WITH THE SOIL MICROBES, AND THE PLANT-ASSOCIATED MICROBIAL COMMUNITY IS REFERRED TO AS THE PLANT'S SECOND GENOME. THE SOIL MICROBIOME PLAYS A CRUCIAL ROLE IN PLANT HEALTH AND FITNESS. PLANT-ASSOCIATED MICROBES ARE IMPORTANT IN MANY ECOSYSTEMS AS DECOMPOSERS, SYMBIONTS, COMMENSALS AND PATHOGENS. HOWEVER, THE IMPACTS OF CECS ON SOIL AND ROOT MICROBIOMES, AND PLANT-MICROBE INTERACTIONS ARE LARGELY UNKNOWN AND THEREFORE NEED TO BE INVESTIGATED. USE OF RWW CHANGES SEVERAL SOIL PARAMETERS (E.G. PH, AND CONCENTRATIONS OF HEAVY METALS AND PHARMACEUTICAL PRODUCTS) THAT INFLUENCE THE DIVERSITY OF SOIL MICROBIAL COMMUNITIES. SOIL PH INFLUENCES SOLUBILITY OF METALS AND HAS POTENTIAL TO CHANGE THE SOIL MICROBIOME. METALS CHANGE THE DIVERSITY AND PHYSIOLOGICAL FUNCTIONS OF NODULE-INDUCING BACTERIA (E.G. BRADYRHIZOBIUM SPECIES) AND DECREASE SPORULATION AND DIVERSITY OF ARBUSCULAR MYCORRHIZAL FUNGI (AMF). HEAVY METALS ARE PHYTOTOXIC AT HIGH CONCENTRATIONS, AND REDUCE NODULATION IN SOYBEAN, LEGUME GROWTH AND YIELD, AND ALSO ALTER SOIL MICROBIAL BIOMASS AND STRUCTURE. IN ADDITION, METALS CAN INTERACT SYNERGISTICALLY WITH ANTIBIOTICS TO INCREASE THEIR POTENCY WHICH WOULD ENHANCE THEIR EFFECTS ON SOIL MICROBES AND PLANT-MICROBE INTERACTIONS. SOYBEANS EARN MORE THAN $46 BILLION/YEAR IN FARM CASH REVENUE IN THE USA ALONE, AND THEY ARE A POPULAR ROTATION CROP BECAUSE THEY INCREASE SOIL NITROGEN THROUGH MUTUALISM WITH BRADYRHIZOBIUM SPP. THE SOYBEAN-BRADYRHIZOBIUM INTERACTION HAS GREAT ECONOMIC VALUE TO SOYBEAN PLANTS AND GRAIN CROPS THAT ARE GROWN IN ROTATION WITH SOYBEANS SO THAT THEY CAN TAKE ADVANTAGE OF THE N FIXED BY THE SOYBEAN-BRADYRHIZOBIUM INTERACTION. CROP ROTATION WITH SOYBEAN REDUCES THE AMOUNT OF CHEMICAL FERTILIZERS APPLIED TO THE SUBSEQUENT GRAIN CROP, THEREBY REDUCING THE COST OF PRODUCTION AND ENVIRONMENTAL POLLUTION.?USING LIQ,UID CHROMATOGRAPHY-MASS SPECTROMETRY (LC-MS) WE WILL MEASURE THE CONCENTRATION OF 17 CECS COMMONLY FOUND IN RWW IN SOUTHERN CALIFORNIA IN DIFFERENT SEASONS OF THE YEAR. WE WILL USE FOUR CECS THAT OCCUR FREQUENTLY AND IN HIGHER CONCENTRATIONS TO DETERMINE EFFECTS OF CECS ON SOIL, ROOT AND NODULE MICROBIOMES OF SOYBEAN USING DNA SEQUENCING AND ANALYSIS. IN ADDITION, USING QUANTITATIVE REAL TIME PCR WE WILL EVALUATE HOW THE SELECTED CECS IMPACT SOYBEAN INTERACTION WITH BRADYRHIZOBIUM JAPONICUM USDA 110 IN THE PROCESS OF NODULE INITIATION AND FORMATION. SOYBEANS AND OTHER LEGUMES FIX NITROGEN IN THE NODULES AND THIS INCREASES SOIL NITROGEN AVAILABLE TO SOYBEANS AND OTHER CROPS. SOYBEANS RECEIVE UP TO 75% OF THEIR NITROGEN FROM NITROGEN FIXATION. THIS IS A NATURAL PROCESS OF IMPROVING SOIL FERTILITY AND REDUCING FERTILIZER APPLICATION AND ENVIRONMENTAL POLLUTION. AS A RESULT OF IRRIGATION WITH RWW CONTAINING CECS THE PROCESS OF NODULE INITIATION AND FORMATION, AND SUBSEQUENT NITROGEN FIXATION CAN POTENTIALLY BE INTERFERED WITH LEADING TO REDUCED SOIL NITROGEN AND SOYBEAN YIELD. THEREFORE OUR GOAL IS TO DETERMINE THE EFFECTS OF CECS ON THE SOYBEAN NODULE INITIATION AND FORMATION. THE SOIL AND SOYBEAN ROOTS AND NODULES CONTAIN MANY MICROORGANISMS THAT ARE IMPORTANT FOR PROTECTING PLANTS AGAINST DISEASE AND HARSH ENVIRONMENTAL CONDITIONS. HIGH LEVELS OF CECS IN THE SOIL HAVE POTENTIAL TO CHANGE THE COMPOSITION OF THESE MICROORGANISMS. THEREFORE WE WILL DETERMINE THE EFFECTS OF CECS ON SOIL AND SOYBEAN ROOTS AND NODULE MICROBIOMES. DATA OBTAINED FROM THIS STUDY WILL IMPROVE OUR UNDERSTANDING OF EFFECTS OF CECS ON IMPORTANT PLANT-MICROBE INTERACTIONS AND FORM A BASIS FOR IMPROVING THE QUALITY OF RWW USED IN AGRICULTURAL AND LANDSCAPE IRRIGATION. OUR FINDINGS WILL BE COMMUNICATED TO THE LOCAL WATER DISTRICTS TO HELP INITIATE DISCUSSION ON HOW TO REDUCE CECS IN RWW. DURING THE DURATION OF THE GRANT WE WILL TRAIN SEVERAL MIDDLE SCHOOL STUDENTS, THEIR TEACHERS AND SEVERAL UNDERGRADUATE STUDENTS ON THE ROLE AND IMPORTANCE OF PLANT-MICROBE INTERACTIONS IN FOOD PRODUCTION AND NUTRIENT CYCLING, AND WHY SUCH INTERACTIONS SHOULD BE PROTECTED FROM CECS.