EXTRACTING SECONDARY METABOLITES FROM BACTERIAL ENDOPHYTES TO SUPPRESS OR PROMOTE SWEET SORGHUM AND WEEDS

Endophytic bacteria are ubiquitous in agricultural settings and have the potential to drastically affect plant growth both positively and negatively. These complex relationships play a key role in plant nutrition and are therefore of great interest to the agricultural community and beyond. With my dissertation work, I have had the opportunity to examine the relationship between endophytic bacteria and plants in various ways. The first part of my dissertation investigated how the microbial diversity found in soil affects the below- and above-ground traits of Sorghum bicolor. In the second section, I focused on a particular strain of bacteria that inhibits plant growth. Thus far, I have measured seed germination, root and shoot biomass, and the nutrient content of soil and Sorghum bicolor that was treated with microbial inocula of different diversities as seeds. Plant nutrient assimilation and productivity was positively correlated with the number of bacterial strains present in the soil in greenhouse trials. I was able to identify several combinations of bacterial strains that may have the potential to increase plant performance and I am excited to explore them further. Our results suggest that a biodiversity-ecosystem functioning experimental approach could prove useful in identifying and developing promising probiotic mixture inoculants to optimize plant growth particularly in marginal soil environments. I have identified a strain of endophytic bacteria that inhibits plant growth and could therefore be used as an herbicide. Herbicide resistance is a major problem in agriculture and finding novel ways to eliminate plants that compete with crops for soil nutrients is essential if we are to provide enough food for a growing population. I am working with researchers in the School of Pharmacy at the University of Kentucky to investigate what substances are being produced by this bacterial strain