Metal(loid) Biogeochemistry

Microorganisms contribute greatly to the biogeochemical cycling of metals and metalloids on Earth through transformational processes such as redox, complexation, and adsorptions.  These transformations contribute substantially to the availability of these nutrients and/or pollutants to organisms.  We take a laboratory- and field-based approach to examine biotic and abiotic transformation mechanisms, microbial communities and activities, biomineral formation, and resulting geochemistry that contributes to the overall health of natural and heavily polluted
environments. Current projects in the lab include fungi-induced selenium transformations, microbial manganese oxidation and biomineralization, and iron-sulfur-carbon cycling in riparian wetlands.

Project: Simultaneous transformation of manganese and selenium by fungi

Previous work by PI Santelli and others (1, 2, 3, 4 ) has shown that fungi are capable of making biominerals of brown manganese oxides by oxidizing manganese (II) dissolved in water.

Within the past few years, Santelli Lab alumna Carla Rosenfeld led a study looking at the potential for six fungi to reduce selenium from selenate or selenite, the phases that are mobile and bioavailable to organisms, to both solid and gas phases. The fungi make amorphous red nanoparticles of selenium that turn the biomass red! At first glance, these reduction-oxidation processes shouldn’t happen at the same time, but it turns out they can! A study led by Carla Rosenfeld, Mary Sabuda, and coauthors showed that the fungi can reduce Se and oxidize Mn simultaneously. This has really important implications for understanding current and ancient global biogeochemical cycles on Earth.

Read this 3-minute-read summary of the project, written by Mary Sabuda!

p sporulosum 0.1 SeO3_coated_6

(Scanning Electron Microscope image of Se nanoparticles; via Carla Rosenfeld)

Ongoing project: Unraveling the genetic mechanisms behind fungal Se reactions using interdisciplinary transcriptomics and geochemical approaches

Mary Sabuda, Jackie Mejia, Katie Schroeder, and PI Cara Santelli are collaborating with the University of Minnesota Genomics Center and the Minnesota Supercomputing Institute on this NSF CAREER project.

se transcriptomics photo

(Liquid media cultures showing common red reduction color; photo by Mary Sabuda)

Ongoing project: Fungal reduction of elevated selenate [Se(VI)] concentrations

Megan Wedal, Mary Sabuda, and Jackie Mejia conducted a study on the reduction of Se(VI) through time.

Ongoing project: Assessing the impact of organic carbon source and concentration on fungal selenium transformations

Mary Sabuda, Jackie Mejia, Megan Wedal, Brayden Kuester, and Cara Santelli are collaborating on this NSF CAREER project. Look out for results in the future!

pyreno plate oc expt photo

(Solid media agar plate showing fungal growth; photo by Brayden Kuester)


KAWE GIDAA-NAANAAGADAWENDAAMIN MANOOMIN “first we should consider manoomin / psiη (wild rice)”

The Santelli lab is part of a highly interdisciplinary collaboration between Great Lakes Tribal communities and University of Minnesota researchers that prioritizes Tribal views in order to identify and tackle the threats faced by manoomin/psiη (wild rice) and its habitat and to further protect Indigenous resource sovereignty.  This project integrates the cultural significance, ecology, and policy of manoomin.

This project is funded by UMN Grand Challenges and the Institute on the Environment.

Learn more at the manoomin project website, Facebook page, or from this brief summary.


Microorganisms play an integral role in transforming pollutants in the environment. These processes can be harnessed for cleaning up heavily impacted environments through passive techniques or advanced technologies. The Santelli lab conducts research on bioremediation of manganese in coal mine drainage as well as selenium bioremediation from industrial waste streams and mining processes.

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