A Helpful Fungus Among Us

A Helpful Fungus Among Us

Mine wastewater bioremediation on Minnesota’s Iron Range

By Evan Whiting

When people think of fungi, they typically conjure images of mushrooms: portobellos, oysters, truffles, or shiitakes. But a mushroom—the fruiting body we see above ground—is merely the tip of the iceberg when it comes to fungi. Most fungi are comprised of a tangled network of small thread-like structures called hyphae. Others, like yeasts, are microscopic, consisting only of single cells.

In fact, there is a huge diversity of fungi out there—some experts estimate that there are over two million species of fungi living on Earth today. And they’re important members of modern ecosystems. Excellent scavengers and nutrient recyclers, many fungi also gather materials from their surroundings and can even capture and store environmental contaminants. Experts are actively working to understand the underlying mechanisms, but scientists, engineers, and industry professionals also see the potential for using fungi in bioremediation—the cleanup of environmental contaminants or pollutants using living organisms, usually microbes.

Dr. Cara Santelli, an associate professor of Earth & Environmental Sciences and a member of the University of Minnesota Biotechnology Institute, is an expert on bioremediation and the interface between microbes and minerals. Santelli and her colleagues investigate organisms with the potential for bioremediation of mining waste, including several species of fungi. One of her ongoing projects, funded by MnDRIVE Environment, involves a species of fungus native to northern Minnesota’s Iron Range, where high concentrations of metals in the wastewater from an inactive underground iron mine could, if left untreated, threaten ecosystems and natural resources on the surface.

Located near Lake Vermilion and the Boundary Waters Canoe Area Wilderness, the Soudan Iron Mine was once a prolific source of iron ore. In the 1960s, when mining operations shut down, the mine became a research and educational facility. But more than fifty years later, there are still lingering issues with toxic metals in the mine’s wastewater, which is currently treated with expensive ion-exchange filters. Luckily, there may be a cheaper, local, and ‘organic’ solution to this problem: bioremediation with a native species of fungus (Periconia sp.) that grows in the salty, metal-rich waters in the depths of the Soudan Mine. Periconia is capable of producing manganese oxide minerals that incorporate metal ions in their chemical structures, much like blocks in a microscopic game of Tetris.

Dr. Brandy Stewart, a postdoctoral researcher in the Santelli Lab, has been studying this fungal bioremediation system in detail. Stewart is an expert in biogeochemistry, or the interplay between chemicals, microbes, and their environment. With additional background in environmental consulting, she brings a wealth of knowledge and experience to this new project. Currently, Stewart studies the optimal growth conditions for the project’s focal fungus, as well as how efficiently it produces manganese oxide minerals using nearby metal ions from the surrounding brine.

The fungus needs a cocktail of nutrients to grow and remain healthy, but the actual wastewater from the mine might not be the ideal growth medium. Even for this mighty fungus, certain metals, like copper, can be toxic at higher concentrations, so Stewart has set out to facilitate the removal of these metals without hurting the fungus itself. She likens this to our own dietary choices: “If you ate nothing but doughnuts, you probably wouldn’t be very healthy, but if you ate well and got plenty of fruits and veggies most of the time, you could still have a doughnut every once in a while and be okay.”

Thankfully, the fungus seems to grow quite well in the suboptimal, mine-like conditions simulated in the laboratory, especially when grown in the presence of carpet fibers. These fibers may be acting as a sort of ‘scaffolding’ upon which the fungus can grow, or even as an additional food source for the fungus. Regardless, Stewart has found that the presence of carpet fibers dramatically improves the growth and productivity of the fungus, which creates a thick biofilm where the manganese oxide minerals form and accumulate . As revealed by X-ray fluorescence images, these minerals are often laden with captured metals, demonstrating the efficiency of this system for removing metals from wastewater.

 

Periconia sp

X-ray fluorescence imagery showing very similar groupings of manganese oxide minerals (left) and copper ions (right) along strands of Periconia sp. fungal hyphae growing in the lab. Courtesy of Brandy Stewart, UMN.

Although still in the experimental stages, Santelli and Stewart eventually hope to build larger bioreactors to scale up their fungal bioremediation system for applications in the Soudan Mine. These bioreactors may be able to help prolong the lifespans of the ion-exchange filters already in use—or potentially replace them, if they prove to be at least as effective at removing metals like copper, cobalt, and nickel from the mine’s wastewater. These metals are not just potential environmental contaminants; they’re also economically important for myriad purposes, including electronics and battery production. If enough of these metals could be efficiently captured in manganese oxides produced by fungi and later recovered, we could potentially capitalize on them.

And mining wastewater might be just the beginning, according to Santelli. There are large amounts of dissolved solids in many types of industrial wastewaters, so there is great potential for using fungi (and/or other microbes) for bioremediation of contaminants in wastewaters well beyond the Iron Range. With such a huge diversity of fungi out there, it’s only a matter of time until another helpful fungus among us becomes the next big hit in bioremediation.

Evan Whiting is a PhD Candidate in the Department of Earth & Environmental Sciences at the University of Minnesota and an affiliate writer in the University of Minnesota Science Communication Lab. He can be reached at whiti101@umn.edu.

Feature photo: Photomicrograph of Periconia sp. fungal hyphae. Courtesy of Brandy Stewart, UMN

Fighting Farmland Pollution with Fungi

Fighting Farmland Pollution with Fungi

With support from the MnDRIVE Environment Initiative, doctoral candidate Laura Bender harnesses the power of soil fungi to help plants absorb pollutants.

by Kyle Wong

To ensure a healthy crop, Minnesota farmers carefully track soil health, nutrients and the quantity of water flowing through their fields. Since 2015, Minnesota’s Buffer Law also requires farmers to tend to historically overlooked land along the edge of these fields. The law mandates a 50-foot buffer along farm fields bordering public waterways, including irrigation and drainage ditches, to help reduce contamination from farm runoff. Instead of corn, soybean and other cash crops, buffer zones are full of perennial plants and trees adept at absorbing excess nutrients flowing from the fields. With financial assistance through environmental programs like the federal Conservation Reserve Program, farmers have both the mandate and the incentives to establish quality buffers. 

Like their commercial counterparts, plants in buffer zones naturally take up nutrients, but researchers like graduate student Laura Bender, hope to improve the process by focusing on fungi living beneath the soil. Soil fungi colonize the roots of buffer plants to form a symbiotic, or mutually beneficial, relationship. “These relationships help plants take up pollutants that would otherwise escape to the waterways, but soils are often degraded through decades of tillage and fertilizer application and compaction,” Bender notes. “The fungi communities that are naturally present in soil are often degraded or absent.” Supported by a 2018 MnDrive Environment seed grant, Bender works to restore those fungal communities to strengthen buffer plants and keep Minnesota waters clean. 

Bender works with several companies working with fungal amendments and measuring techniques. MycoBloom, for example, developed a fungal amendment containing a type of fungus called  arbuscular mycorrhizal (AM). AM fungi have been shown to help plants absorb nutrients more efficiently. But soil types vary across Minnesota, so Bender has worked with farmer Dave Legvold to test the amendment on the buffer zones on his farm. She collects data from his testing site each year to identify how well the amendment might work in the rest of Minnesota.

Bender collects soil and plant samples from the field site’s buffer zone and measures the level of phosphorus, one of the most common farm nutrients harmful to waterways. Alongside the buffer, she also collects dissolved groundwater. The Research Analytics Lab at the University of Minnesota processes the soil, plant and groundwater samples to calculate the phosphorus levels in each component. Bender uses the data to trace the amount of phosphorus that the buffer plants absorb and the amount that escapes to the water. “We’re measuring how the phosphorus level changes each year to see if the fungi amendment is removing it from runoff water that enters the buffer,” she says.

Phosphorus levels in the buffer are only part of the story; Bender wants to observe the interactions between the AM fungi and the buffer plants. To do so, she needs to look below the soil and analyze the mycorrhizal interactions at a microscopic level. Here, she partners with the company MycoRoots to assess how well the AM fungi colonize the roots of buffer plants. MycoRoots documents the surface area of plant roots covered by AM fungi. Bender uses the data to understand the role that mycorrhizal association plays in phosphorus uptake. Data from 2018 and 2019 revealed that plants with high root coverage from AM fungi tended to take up more phosphorus, leading to lower phosphorus levels in both the soil and groundwater. Bender will conduct more data analysis this fall before forming a conclusion. 

Ultimately, Bender hopes to guide state policy to help farmers understand the best practices for their buffers. To build awareness, Bender plans to lead an online workshop this fall to bring farmers, policymakers and industry partners together for a discussion on buffer-related issues and policies. “It’ll be related to specific topics – different fungi people have used, success or failures in certain settings, opportunities for collaboration, etc. The goal is to identify where others have used amendments and how it has worked for them.” 

With additional funding from MnDRIVE Environment and the University’s Institute on the Environment, Bender hopes to continue research and strengthen her partnerships with the community. Proper guidelines on buffer strips and fungal amendments can help Minnesota landowners establish healthy buffers that benefit them financially and help conserve the environment.

This research was supported by MnDRIVE Advancing Industry, Conserving Our Environment at the University of Minnesota.

Kyle Wong is a writing intern in the University of Minnesota Science Communications Lab, majoring in Microbiology. He can be reached at wong0511@umn.edu

Postdoctoral Research Associate

Postdoctoral Research Associate in Microbiology, Pharmacology, and Gastroenterology

A postdoctoral position is immediately available in the BioTechnology Institute and Department of Medicine, Div. of Gastroenterology, at the University of Minnesota.

Mike Sadowsky and Alex Khoruts are looking for a highly motivated postdoc to work on a project related to the development of new and novel formulations of microbiota-based for a variety of human diseases. This project follows up on our encapsulation technology for intestinal microbiota transplantation in adult patients. However, an important goal is development microencapsulation to enable oral administration of live microbiota to patients who may have difficulty with capsules, e.g., young children. This postdoctoral project will help develop the technology and follow engraftment of intestinal microbiota in animal models and patients using DNA sequencing, qPCR, metagenomics and culturing methods.

All applicants must have a Ph.D. in microbiology, pharmacology,  or a relevant field. Expertise in microbiology, microbial ecology, pharmacology, and analytical chemistry, is highly desired.

The position is for 2 years, and is annually renewable depending on performance and availability of funding The successful candidate will receive training in professional and personal development, research collaboration, presentation and publication of results, outreach, and mentoring. The position includes a competitive salary and health insurance. Review of applications will begin immediately and will continue until the position is filled. A near-term start date is desired.

Applications should include: (i) brief cover letter, (ii) curriculum vitae, (iii) a brief description of past research accomplishments and future research goals (under two pages), and (v) the names and contact information for three references. All materials should be submitted as a single combined PDF to Alex Khoruts (khour001@umn.edu) and Mike Sadowsky (sadowsky@umn.edu) with “Postdoc Application” in the subject line. Any questions should also be directed to these email addresses.