The studies presented in this dissertation show the interacting effects of agriculturally derived DOM, sunlight, and reactive oxygen species (ROS) on Escherichia coli (C3000) and Enterococcus faecalis (ATCC 29212) survival. Cattle feces was collected from a commercial farm in northeast Georgia and made into a filter-sterilized extract referred to as cattle fecal extract (CFE). CFE was diluted to represent DOM concentrations in water resulting from low to high fecal input, and exposed to artificial sunlight for 12 h. Irradiated spiked water (I-DOMW), non-irradiated spiked water (N-DOMW) and phosphate buffered water microcosms were inoculated with mid-logarithmic phase aliquots of individual bacterial strain cultures (~103 - 106 colony forming unit (CFU) mL-1), in monoculture or as co-culture. Microcosms were monitored periodically in the dark for bacterial concentration, nutrient loss/uptake, ROS, transcriptomic changes and metabolite production. Singlet oxygen, hydrogen peroxide (HOOH) and superoxide radicals were detected during 12 h of irradiation. In the presence of E. coli only, extracellular HOOH dropped from ~15M to 3-FC). Most importantly, we observed a form of exploitative competition between these strains in DOMW microcosms, where chorismate and arginine/ornithine served as shared public goods for the biosynthesis of enterobactin and polyamines. For this cooperative competition to be efficient, both bacteria increased the expression of genetic networks associated with oxidative stress, bacteriophage activation, non-ribosomal peptide production, plasmid loss and virulence, toxin-antitoxin systems, quorum sensing, biofilm formation and antimicrobial resistance. We provide for the first time evidence of such cooperation between two distantly related species of bacteria.