Publications by Colleges and Departments (MSU - Bozeman)
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Item Selenate bioreduction in a large in situ field trial(Elsevier BV, 2024-04) Hendry, M. Jim; Kirk, Lisa; Warner, Jeff; Shaw, Shannon; Peyton, Brent M.; Schmeling, Erin; Barbour, S. LeeRemoving selenium (Se) from mine effluent is a common challenge. A long-term, in situ experiment was conducted to bioremediate large volumes (up to 7500 mc d−1) of Se(VI)-contaminated water (mean 87 μg L−1) by injecting the water into a saturated waste rock fill (SRF) at a coal mining operation in Elk Valley, British Columbia, Canada. To stimulate/maintain biofilm growth in the SRF, labile organic carbon (methanol) and nutrients were added to the water prior to its injection. A conservative tracer (Br−) was also added to track the migration of injected water across the SRF, identify wells with minimal dilution and used to quantify the extent of bioreduction. The evolution of the Se species through the SRF was monitored in time and space for 201 d. Selenium concentrations of <3.8 μg L−1 were attained in monitoring wells located 38 m from the injection wells after 114 to 141 d of operation. Concentrations of Se species in water samples from complementary long-term (351–498 d) column experiments using influent Se(VI) concentrations of 1.0 mg L−1 were consistent with the results of the in situ experiment. Solid samples collected at the completion of the column experiments confirmed the presence of indigenous Se-reducing bacteria and that the sequestered Se was present as insoluble Se(0), likely in Se-S ring compounds. Based on the success of this ongoing bioremediation experiment, this technology is being applied at other mine sites.Item Diversity and evolution of nitric oxide reduction in bacteria and archaea(Proceedings of the National Academy of Sciences, 2024-06) Murali, Ranjani; Pace, Laura A.; Sanford, Robert A.; Ward, L. M.; Lynes, Mackenzie M.; Hatzenpichler, Roland; Lingappa, Usha F.; Fischer, Woodward W.; Gennis, Robert B.; Hemp, JamesWith the advent of culture-independent techniques for studying environmental microbes, our knowledge of their diversity has exploded, uncovering unique organisms, pathways, and proteins carrying out important processes in the biosphere. Novel biochemical reactions are often proposed based on sequence data, but experimental validation is difficult and rare. In this work, we used environmental sequence data to find enzymes that produce the greenhouse gas N2O from NO and validated our hypothesis with experiments. These new enzymes likely contribute to global N2O fluxes and expand the breadth of nitrogen cycling. We also demonstrated that these enzymes evolved multiple times from oxygen reductases, indicating that the evolutionary histories of aerobic respiration and denitrification—and more broadly the oxygen and nitrogen cycles—are tightly connected.