Rhizobia are involved in fixing atmospheric nitrogen into bioavailable forms in symbiosis with legume crops. They play a crucial role in sustainable agriculture where they alleviate requirements for chemical fertilizers. Many factors affect the growth and viability of rhizobia within the soil and hence impact this important mutualism. One such factor is bacteriophage, obligatory intracellular parasites that can influence the phenotypic as well as genotypic diversity of rhizobia. Infection by bacteriophage can result in cell lysis followed by the release of more bacteriophage into the soil microbiome. Alternatively, rhizobia may bear resistance genes that allow them to resist the bacteriophage infection. In this project, the model organism  Sinorhizobium meliloti, the natural symbiont of alfalfa plants, is used to study the phage-rhizobium interaction.  S. meliloti  isolates from 33 sites across North Dakotan were isolated and stocked. Selected soil samples were used for the isolation of bacteriophage capable of infecting  S. meliloti. The isolated phages are being employed to assess the phage resistance-sensitivity profiles across the rhizobium library and will be employed in pan-GWAS analysis to anticipate the phage resistance genes in the rhizobium library. Additionally, series of experiments are being conducted to explore the ability of phage or phage cocktails to eliminate the sensitive rhizobium strains from the soil mesocosms which will pave the path for the potential use of “phage therapy” in manipulating the nodulation.