Rosenfeld C E, Kenyon J A, James B R, Santelli C M
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.
Geobiology. 2017 May;15(3):441-452. doi: 10.1111/gbi.12224. Epub 2017 Jan 2.
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.
已知微生物过程介导硒（Se）的氧化还原反应，对硒的形态、生物有效性以及在整个环境中的迁移有重大影响。虽然这些过程通常在厌氧细菌中进行研究，但好氧真菌在硒氧化还原反应中所起的作用对于以微生物活动为主导的富硒土壤系统可能很重要。我们对六种耐金属子囊菌存在时真菌的生长、好氧硒（IV、VI）还原以及硒的固定和挥发进行了量化。我们发现溶解态硒的去除取决于真菌种类、硒的形态（即亚硒酸盐或硒酸盐）以及硒的浓度。所有六种真菌都能生长并从溶液中去除溶解态的硒（IV）或硒（VI），其中五种真菌将两种含氧阴离子都还原为硒（0）生物矿物，并且所有六种真菌都通过挥发去除了至少15%-20%的供应硒。然而，所有真菌的生长速率都随着硒（IV、VI）浓度的增加而降低。在存在0.01 mM硒（IV）的情况下，所有真菌在10天内去除了85%-93%的溶解态硒（IV），但在以0.01 mM硒（VI）生长时，仅去除了约20%-30%的硒（VI）。真菌产生的生物矿物通常是直径为50至300纳米的无定形或准晶态球形硒（0）纳米颗粒。我们的结果表明，常见土壤真菌的活性可以影响硒的形态和分布，因此这些生物体可能在硒污染环境的解毒中发挥作用。
