In my research I investigate the microorganisms generally referred to as rhizobia. These soil bacteria form a nitrogen-fixing symbiosis with legumes and, besides its fascination from a purely scientific point of view, this relationship is important to agriculture and to conservation biology, as the symbiosis makes an important contribution to the nutrition of important crops and members of a variety of ecosystems.
One focus of my research is the control of gene expression in the bacterium Sinorhizobium meliloti, the symbiont of alfalfa. Using tools from microbial genetics (production and characterization of mutants), microbiology (characterization of patterns of growth) and biochemistry (assay of enzymes), I am studying the mechanisms by which S. meliloti responds to changes in nutrient availability by regulating the production of enzymes involved in carbon nutrition.
Another major area of interest is the symbiosis between rhizobia and desert woody legumes, a project begun by Jim Blauth and David Schrum. Students working on this project can expect to characterize rhizobia with respect to their growth rates, nutrient use, resistance to antibiotics and environmental stressors, and nodulation patterns.