Our current research focuses mainly on hyperthermophiles, which are microorganisms that grow near 100°C, and on the roles of metals in microbial metabolism. In a basic science project, we are using the archaeon Pyrococcus furiosus, which grows up to 103°C, to study the structure and evolution of modern day respiratory complexes using genetic, structural and biochemical approaches. The cryoEM structure of a nickel-iron containing respiratory complex that produces hydrogen gas and pumps sodium ions was recently determined (Cell 173, 1636, 2018; doi: 10.1016/j.cell.2018.03.071). In an applied project, the bacterium Caldicellulosiruptor bescii, which grows up to 90°C, is being genetically-engineered to convert plant biomass to useful fuels and chemical using a systems biology-based approach. We recently demonstrated that this organism contains a novel tungsten-containing enzyme as part of its glycolytic pathway (J. Biol. Chem. 294, 9995, 2019; doi: 10.1074/jbc.RA118.007120). In an environmentally-related project, metal-resistant, nitrate-reducing microbes that we isolated from a nuclear waste processing facility are being characterized. We recently demonstrated that molybdenum, an essential metal for microbial nitrate reduction, is depleted in this environment that is otherwise rich in a range of other metals (Environ. Microbiol. 21, 152, 2019; doi: 10.1111/1462-2920.14435).