Minnesota’s Fantastic Fungi

By Isaac Conrad

The Iron Range in Northern Minnesota is known for many things–tall pine forests, crystal clear waters, and blue-collar communities. True to its name, the Range is rich in deposits of industrial metals, and for decades, environmental groups, industry, and local communities have debated the fate of mining in the region. Some say mining is necessary to support the working communities there, and others say the health risks for local communities and ecosystems outweigh the temporary economic boost. Either way, this debate is familiar throughout the Northland.

The Soudan Mine, not far from the Boundary Waters Canoe Area, was once a rich source of iron. When it ceased operation in 1962, however, residue from toxic metals lingered in wastewater surrounding the mine. Left untreated, these toxins threatened the ecosystems and natural resources vital to the Northland economy, culture, and identity. University of Minnesota researcher, Cara Santelli, (BTI / Earth and Environmental Science) grew up near Lake Vermillion and the remnants of the Soudan Mine. Today, she is searching for solutions to help clean up the mine’s contaminated wastewater.

Current approaches to treating toxic wastewater are expensive, so Santelli is looking for a cheaper, more natural solution. Periconia, an indigenous fungus, shows promising potential for bioremediation–the cleanup of environmental contaminants via organisms, usually microbes. Growing in the salty, metal-rich waters of the abandoned Soudan, Periconiaproduces manganese oxide. This mineral can effectively eliminate toxic metals by incorporating them into its chemical structure. With funding from the MnDRIVE Environment program and other sources, Santelli and her colleagues hope to capitalize on this unique ability, but first, Periconia needs to grow at an industrial scale.

Brandy Stewart, a postdoctoral researcher in the Santelli Lab, has been tasked with determining the perfect conditions for Periconia to grow. The fungus may be native to the region, but the deep waters of the mine are not the optimal condition for Periconia when used for bioremediation. To overcome this challenge, Stewart built bioreactors to simulate the mine water conditions and test potential strategies for more productive fungal growth.

Preliminary results demonstrate that Periconia can grow quite well in the suboptimal, mine-like conditions–especially in the presence of carpet fibers. Carpet fibers provide a base to which the fungus can attach and anchor. Stewart found that the presence of these carpet fibers dramatically improves the growth and productivity of the fungus; productive Periconia creates a thick biofilm that uses manganese oxide to capture the toxic metals and store them in its hyphae. As shown by x-ray fluorescence images, manganese oxide effectively captures copper, one of the remaining toxic metals in the Soudan Mine.

X-ray fluorescence imagery showing very similar groupings of manganese oxide minerals (left) and copper ions (right) along strands of lab grown Periconia hyphae (tangled, thread-like structures comprising the main body of the fungus). Courtesy of Brandy Stewart.

Although still in experimental stages, Santelli and Stewart hope to build larger bioreactors to scale up their fungal bioremediation system for application in the Soudan. These bioreactors may help prolong the life of current, expensive wastewater treatments, or even serve as a potential replacement if they prove to be effective at capturing metals like copper, cobalt, and nickel. While Periconia will not bring about an end to mining debates in the Northland, it offers promising potential for bioremediation on the Iron Range and beyond.

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