Graduate Programs in the Life Sciences

Research Focus

In the broadest terms my research program focuses on issues that relate to soil microbial diversity: its extent, its regulation, and its impact on biogeochemical cycles that regulate soil fertility and influence atmospheric chemistry. My lab is currently using nitrogen fixation as a model system for exploring the role of microbial diversity on ecosystem function. Free-living diazotrophs in soils provide the dominant natural source of fixed N in many terrestrial systems, and yet we know remarkably little about the ecology and evolution of these microorganisms. We are using a novel approach that combines Stable Isotope Probing (SIP) with environmental genomics to examine genomic information from non-cultivated diazotrophs. This research will significantly advance our understanding of the environmental mechanisms that regulate the diversity and activity of free-living N-fixing microorganisms in soils and will provide insights on the ecology and evolution of a microbial process that is of central importance to the global N cycle.