Positive Health Online

Abstract

ROSENFELD and COLLEAGUES, 1. Department of Mineral Sciences, Smithsonian Institution National Museum of Natural History, Washington, DC, USA; 2. Department of Earth Science and BioTechnology Institute, University of Minnesota - Twin Cities, Minneapolis, MN, USA; 3. MIT/WHOI Joint Program in Oceanography, Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA; 4. Department of Environmental Science and Technology, University of Maryland, College Park, MD, USA quantified fungal growth, aerobic Se(IV, VI) reduction, and Se immobilization and volatilization in the presence of six, metal-tolerant Ascomycete fungi to determine whether fungal organisms may therefore play a role in detoxifying Se-polluted environments.

Background

Microbial processes are known to mediate selenium (Se) oxidation-reduction reactions, strongly influencing Se speciation, bioavailability, and transport throughout the environment.

Methodology

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.

Results

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) bio-minerals, 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 bio-minerals were typically 50- to 300-nm-diameter amorphous or paracrystalline spherical Se(0) nanoparticles.

Conclusion

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.

References

Rosenfeld CE1,2, Kenyon JA1,3, James BR4, Santelli CM1,2. Selenium (IV,VI) reduction and tolerance by fungi in an oxic environment. Geobiology;15(3):441-452. doi: 10.1111/gbi.12224. Epub Jan 2 2017 . May 2017.