This award provided funding to study the connection between the geochemistry and geomicrobiology in selenium-contaminated soils. Microbial processes significantly influence selenium (Se) mobility and bioavailability, and of particular interest are microorganisms that can remove excess Se from the food chain and water supplies. While microbial Se transformations in anaerobic environments have been more extensively studied, microbial interactions with Se in aerobic environments (i.e., the majority of soil environments that host plant and animal life) are not well understood. The specific aims of this project were to clarify what microorganisms are involved in Se biogeochemistry and how Se contamination influences and is influenced by microbial diversity in aerobic ecosystems is critical for understanding and predicting Se persistence and environmental impacts.

In order to study microorganisms in soils (also known as the soil microbiome), the research team and I visited field sites in southeast Idaho, where there are known Se contamination problems in the soils. The team includes myself, a postdoctoral fellow, my mentor at University of Minnesota, several undergraduate researchers, and a laboratory technician. The area is actively grazed by cattle every year, and the land managers and cattle owners are concerned that the extra Se in the soils can make it into the food chain and cause negative health impacts for the cattle or people consuming the cattle. We visited the field sites for one week during June 2015, 2016, and 2017 and collected soil samples from several locations within the mines and outside the mines each year. After sampling, soils are immediately frozen at -80 degrees C to preserve soil DNA. Once back at the lab, DNA was extracted from soil samples and microbial (bacterial and fungal) DNA was sequenced using high-throughput DNA sequencing (Illumina MiSeq). After intensive data processing using the UMN supercomputer, the data was analyzed to understand aspects of the microbial community living in the contaminated Idaho soils. This analysis identified that mining history was specifically associated with altered fungal and bacterial community structures, even several decades after mine reclamation. The taxonomy of the fungal community indicated that certain Ascomycete families (Trichocomaceae and Pezizomycotina (incertae sedis)) were significantly increased in soils that had high concentrations of Se in them, perhaps due to their ability to tolerate stress. We have also separately isolated several fungal strains that are members of these families, using culturing techniques. We are now working with these strains in the lab to develop potential bioremediation strategies. We can also use these taxonomic and community structure patterns to assess soil health in other areas, and understand potential microbiome signals indicating the presence of contamination. 

Last Modified: 12/29/2017
Modified by: Carla E Rosenfeld