title: Selenium (IV,VI) reduction and tolerance by fungi in an oxic environment.
abstract: Microbial processes are known to mediate selenium (Se) oxidation-reduction reactions, strongly influencing Se speciation, bioavailability, and transport throughout the environment. While these processes have commonly been studied in anaerobic bacteria, the role that aerobic fungi play in Se redox reactions could be important for Se-rich soil systems, dominated by microbial activity. We quantified fungal growth, aerobic Se(IV, VI) reduction, and Se immobilization and volatilization in the presence of six, metal-tolerant Ascomycete fungi. We found that the removal of dissolved Se was dependent on the fungal species, Se form (i.e., selenite or selenate), and Se concentration. All six species grew and removed dissolved Se(IV) or Se(VI) from solution, with five species reducing both oxyanions to Se(0) biominerals, and all six species removing at least 15%-20% of the supplied Se via volatilization. Growth rates of all fungi, however, decreased with increasing Se(IV,VI) concentrations. All fungi removed 85%-93% of the dissolved Se(IV) within 10 d in the presence of 0.01 mm Se(IV), although only about 20%-30% Se(VI) was removed when grown with 0.01 mm Se(VI). Fungi-produced biominerals were typically 50- to 300-nm-diameter amorphous or paracrystalline spherical Se(0) nanoparticles. Our results demonstrate that activity of common soil fungi can influence Se form and distribution, and these organisms may therefore play a role in detoxifying Se-polluted environments.
authors.affiliation: Department of Mineral Sciences, Smithsonian Institution National Museum of Natural History, Washington, DC, USA.|Department of Earth Science and BioTechnology Institute, University of Minnesota - Twin Cities, Minneapolis, MN, USA.
authors.forename: C E
authors.initials: CE
authors.lastname: Rosenfeld
authors.affiliation: Department of Mineral Sciences, Smithsonian Institution National Museum of Natural History, Washington, DC, USA.|MIT/WHOI Joint Program in Oceanography, Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Kenyon
authors.affiliation: Department of Environmental Science and Technology, University of Maryland, College Park, MD, USA.
authors.forename: B R
authors.initials: BR
authors.lastname: James
authors.affiliation: Department of Mineral Sciences, Smithsonian Institution National Museum of Natural History, Washington, DC, USA.|Department of Earth Science and BioTechnology Institute, University of Minnesota - Twin Cities, Minneapolis, MN, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Santelli
mesh_terms: D000332:Aerobiosis; D001203:Ascomycota / Q000254:growth & development / Q000378:metabolism*; D004785:Environmental Pollutants / Q000378:metabolism; D010084:Oxidation-Reduction; D064586:Selenic Acid / Q000378:metabolism; D020887:Selenious Acid / Q000378:metabolism; D012643:Selenium / Q000378:metabolism*; D012988:Soil Microbiology
chemical_list: D004785:Environmental Pollutants; D020887:Selenious Acid; D012643:Selenium; D064586:Selenic Acid