My primary research interests are in geomicrobiology and environmental microbiology. My group studies how microorganisms shape, and are shaped by, their natural environments. My research group studies microbial communities, primarily using cultivation-independent approaches such as genomics (metagenomics) and community proteomics. We work on microbial dissolution and precipitation of minerals, the structure, properties, and reactivity of nanoparticles (many of which are formed by microorganisms), microbial ecology, and microbial evolution. Virtually all of our projects are tied to a field site. Current locations of study are Iron Mountain (northern California), the Angelo Reserve (northern California), the Rifle and East River sites, Colorado, Crystal Geyser, Utah