Enzyme-based coatings developed at the University of Minnesota help protect port infrastructure by disrupting the signals underwater bacteria use to communicate.

By Nick Minor and Kristal Leebrick

In any seaport or freshwater marina around the world, just beneath the surface, and you’ll find an ongoing battle between the boats, docks, bridges—anything made of steel—and a cast of aquatic bacteria in search of a submerged surface to call home. The biocorrosion created by these bacterial hitchhikers is especially dire in cold climates where winter brings the added wear and tear of scraping ice. And Duluth-Superior Harbor is ground zero, as aquatic bacteria corrode nearly 50,000 pounds of steel there each year.

Two University of Minnesota scientists—Randall Hicks, a microbial ecologist in Duluth, and Mikael Elias, a biochemist in the Twin Cities—have developed an enzyme coating they believe could rewrite the story of biocorrosion in Duluth and around the world. Their work shows extraordinary promise in helping prevent biocorrosion in seaports and could have the added bonus of being environmentally friendly.

The scientists’ collaboration began in late 2016, after Elias read about Hicks’s and postdoctoral associate Simon Huang’s work on testing anti-biocorrosion coatings in Gateway, published by the University of Minnesota BioTechnology Institute. The timing was auspicious for Elias. He and his students had recently engineered an enzyme that breaks down the chemical signals bacteria use to coordinate and build things like biofilm, a matrix of proteins and carbohydrates that can lead to biocorrosion. The interruption of those signals is like overlaying an impenetrable static onto construction workers’ walkie-talkies. Without the ability to communicate, the bacteria can’t coordinate enough to build anything.

Communication-disrupting enzymes are well-known and widely available, yet their potential ability to prevent bio-induced corrosion was unknown. In addition, in order to prevent biocorrosion in the Duluth-Superior Harbor, an enzyme needs to be hardy enough to withstand organic solvents of paints, temperature shifts that can kill most plants and animals, and endure scrapes from massive winter ice flows. This is where Elias’ specialty—protein engineering—came into play. Elias refined the enzyme to such an extent that it is now “so stable that we can dilute them into paint, a very harsh treatment for a protein,” says Elias, “and they still remain active.”

After reading about Hicks’s and Huang’s work, Elias reached out and asked if Hicks could squeeze one more coating into his tests. From there, the duo started with a two-month, proof-of-concept test in the lab, made possible through funding from the University’s MnDRIVE Environment initiative, which supports promising research on environmental remediation. In this short-term test, the enzyme, which was suspended in a durable acrylic, outperformed every other coating Hicks had been examining. But the real test lay ahead. After presenting the enzyme coating to companies like PPG, BASF, and Ecolab, Elias and Hicks heard the same message over and over: The companies needed to know if it would remain effective for years, not just two months.

Elias and Hicks received a much larger “demonstration grant” from MnDRIVE, which supported two years of testing, including testing in the Duluth-Superior Harbor. The work exceeded all expectations: over those two years, the enzyme coating was more effective at preventing biocorrosion than any other available coatings and it appears to do no harm to the environment as it kills nothing outright. Currently, 85 percent of the market for anti-biocorrosion coatings is dominated by toxic copper oxide paints. As with nearly every other coating available, copper oxide paints work by brute force, killing the organisms responsible for biocorrosion. Copper oxide’s toxicity to biocorrosive organisms also means it’s toxic to other living things.

Copper oxide paints were technically banned by multiple U.S. states. “But, because there is no alternative,” explains Elias, “the ban is constantly being pushed back.” Copper oxide, a heavy metal and potent environmental toxin, has been accumulating in portside ecosystems around the world for decades.

“The alternative that we’re working on,” says Elias, “is ecological because it’s a protein. A protein, by definition, is biodegradable. It’s amino acids.” The enzyme’s approach—disrupting the communication between bacteria that get biocorrosion started—is utterly novel.

The enzyme coating could rewrite the story of biocorrosion in Duluth and enable additional infrastructure protections to take effect. The aquatic ecosystem around the Duluth-Superior Harbor, along with similar portside ecosystems around the world, could start to recover from decades of copper pollution.

Based on their initial work, the team received funding from the Minnesota Sea Grant and Minnesota Aquatic Invasive Species Research Center-LCCMR to study the coatings’ ability to inhibit biofouling and the adhesion of aquatic invasive species to underwater surfaces.

“This may just be another arrow in the quill of possible coatings that could be used,” Hicks explains cautiously, “but potential applications are certainly way beyond Lake Superior. The market could be potentially unlimited.”

MnDRIVE initiative helps Second Harvest Heartland turn inedible food into useful products.

By Mary Hoff

Every day, Second Harvest Heartland gathers more than 100 tons of food from donors across Minnesota and western Wisconsin and redistributes it to food shelves and others who serve people in need. In the process, the food bank—the second largest in the United States—ends up with some 3 tons of bad cabbage, spoiled milk, too-old-to-eat cereal and other “unfit for consumption” bits and pieces left over from this process.

And pays $200,000 per year to have it hauled away.

Now, Second Harvest is looking to turn this waste into a “third harvest” with the help of a MnDRIVE demonstration grant, University of Minnesota agricultural engineers, and an invention that began as a way to reduce problems with pig poop.

It all began when Bob Branham, director of produce strategy for the food bank, began looking for a way to reduce the need to spend money that could be going to feed people on disposing of inedible organics.

“I’m paying people to take away high-value waste,” he recalls thinking. “Why shouldn’t I keep that waste to the benefit of Second Harvest Heartland?”

Branham reached out to the University of Minnesota where, coincidentally, associate professor of bioproducts and biosystems engineering Bo Hu had recently, with the help of a MnDRIVE seed grant, developed an anaerobic digester system for turning another type of organic material—pig manure—into useful materials. Hu and Timothy LaPara, professor of civil, environmental, and geo-engineering, applied for and received a MnDRIVE demonstration grant proposal to apply the concept to meet Second Harvest needs.

With support from MnDRIVE and the help of undergraduate and grad students, Hu and LaPara designed a two-stage system capable of transforming Second Harvest’s highly variable organic waste stream into heat, fertilizer, and a valuable soil amendment.

Anaerobic digestion has some similarities to traditional composting but is miles beyond it in both technical sophistication and value of output. Whereas composting takes place with organic materials exposed to air and produces a soil amendment, anaerobic digestion relies on bacteria that break down materials in the absence of oxygen and produces a gas that can be burned to produce heat.

“Digestion of food waste is actually a very sexy idea right now,” Hu says, noting that some large cities are banning food waste from landfills, and sustainability advocates are pushing to reduce the greenhouse gas contributions of waste while deriving useful products.

To make the process suitable for application at Second Harvest, Hu and his team refined it to work with a variable waste stream, at a relatively small scale, with a minimal need for water, and with a bio-electrochemical system that removes adverse odors. They also did an economic analysis to determine whether a digester would make dollars-and-cents sense for Second Harvest, which operates on a tight budget and aims to put every extra penny into helping allay hunger and reduce food waste.

The project penciled out, so Hu and team built an experimental digester to refine the process. Among other things, they looked at strategies to reduce odor and corrosiveness of the gas it produces, explored how the mix of digesting microbes might be tweaked over time to meet seasonal changes, and identified ways to automate the process.

Now, with many of the bugs worked out of the system, the team is installing a pilot digester at its Brooklyn Park facility to test its performance with the mix of waste the food bank produces. Once the pilot confirms the functionality of the system, Hu will advise Second Harvest on installing a full-scale facility.

Along with the benefits the system will reap from what is currently treated as a liability, Hu envisions a fourth harvest from the project as well: Inspiration and motivation for other food banks, as well as other businesses that manage organic waste.

Hu says MnDRIVE has been “very vital” in making this research possible because federal grants are increasingly hard to come by.

“It’s actually really good seed money to obtain federal support,” he says. “We are doing applied research, but we are also gaining fundamental knowledge at the same time that will help us [pursue funding from] federal agencies like USDA or the National Science Foundation.”

For his part, Branham is delighted to have the opportunity to do an even better job of making the most of the resources his organization stewards. “This is a whole new validation that waste and renewable energy can be great partners,” he says. “I wish there wasn’t organic waste, but there is—it just happens for a variety of reasons and that’s not going to go away. So let’s find a better use for it to fight food insecurity.”

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UMN researcher Dr. Brandy Stewart studies carbon-rich peat to filter harmful metals from wastewater.

By Lauren Holly

Water flows into our homes every day. We use it to wash our hands, do dishes and, of course, drink. Eventually, it ends up at a wastewater facility where it is treated, filtered, and safely discharged. Stormwater is different. Runoff from pavement, agriculture, and other human activity (think roads, golf courses, etc.) bypasses water treatment facilities. It flows directly into the environment, carrying the micronutrients, metals, and other contaminants picked up along the way.

“Any time major metropolitan populations reside near bodies of water, we raise concerns over how to best protect that water from the inevitable contaminants that arise out of human activity,” says Dr. Brandy Stewart, a University of Minnesota researcher who works in Dr. Brandy Toner’s Low-temperature Geochemistry lab. The group studies how nutrients and metals move through oceans and sediments, including the role microbes play in this complex process.

To help prevent contamination of nearby waterways, industries that use metals and similar contaminants are required to treat stormwater before it is released into the environment. The process can be both time-consuming and costly. Stewart, who studies contaminants moving through soil and waters, is looking at peat as a cost-effective solution for removing metals from stormwater.

Created by decaying plants in bogs and wetlands, peat is a remarkably flexible material. Gardeners prize peat for its ability to retain soil moisture. It’s also an important vehicle for beneficial microorganisms that can help increase agricultural yields. But researchers from the Toner lab were drawn to peat because of its amazing ability to remove metals from water—naturally.

The Toner lab has partnered with American Peat Technology (APT), a Minnesota company producing a commercially available peat product for treating contaminated water. At a field site in Michigan, APT’s product is used to treat water at a metal plating factory. Drainage from the factory runs through large treatment tanks containing peat that captures harmful metals like chromium, cadmium, and zinc.

Stewart’s research, supported by a MnDRIVE Environment Seed Grant, indicated that removal rates were actually higher than the team (Toner and Stewart along with collaborators Dr. Cody Sheik and Paul Eger) initially predicted. But Stewart suspects that peat may not be doing the job on its own. Bacteria and microbes may also contribute to the system’s success, and help sequester contaminants.

“If we figure out the mechanism that is sequestering the chromium, we can try to enhance it and market it to other uses,” Stewart says. Ultimately, her goal is to make peat as efficient as possible. “It’s clearly working, but we want to see if we can use a different amount, or use it at a different temperature,” she explains. “Imagine if we only needed one tank instead of seven.”

Given that it is a natural product, peat is an attractive solution for environmental remediation. It doesn’t require constant upkeep or input of chemical reagents. In fact, peat can sit in the tanks for up to four years without being changed. It’s proving itself to be a low-cost, low-maintenance treatment that ultimately could be a win for both industry and the environment.

UMN researcher in the Elias Lab searches for clues to bacterial communication.

By Kelley Hosieth

When it comes to understanding bacteria, communication is key. Celine Bergonzi, a postdoc in the Elias Research Lab, studies quorum sensing—a signaling system used by microorganisms to stimulate and respond to population density. Quorum sensing also influences the expression of virulence factors in some organisms and plays a role in the formation of biofilms on hospital and industrial surfaces. “Bacterial communication plays a huge role in pathogenicity,” Bergonzi says. “It allows bacteria to adapt to their environment and become more virulent. This process is really amazing and fascinating from an evolutionary point of view.”

One solution to the problem may come from an enzyme called lactonase that blocks bacterial signaling. Understanding how lactonase works could mitigate a range of problems from biofouling in the aquaculture industry to hospital-acquired infections. It may ultimately help researchers learn more about microbial pathology and the evolution of human disease.

Bergonzi’s interest in the evolution of disease began during her training as an archaeologist in her native France and eventually led to a second master’s degree in biological anthropology. There she discovered the work of Mikael Elias, a biochemist studying protein evolution. Bergonzi joined the Elias Research Lab, and when the group moved to Minnesota, she began work on a PhD in biochemistry.

Genomic sequencing technologies now allow scientists to analyze bones, skin, blood, and hair for traces of diseases that affected ancient populations. Most of this work relies on DNA, but Bergonzi believes that trace proteins, such as enzymes, could hold valuable clues to the evolution of disease and the interactions between human populations.

For now, Bergonzi continues to focus on quorum sensing, and how it can enrich our understanding of bacteria – in the past and future.

Kelley Hosieth is a Genetics and Cell Development major at the University of Minnesota’s College of Biological Sciences and an intern in the BioTechnology Institute’s Science Communications Training Program.

University of Minnesota researchers pair plants with microbes to remove arsenic from contaminated soils.

by MaiLei Meyers

The contamination of soil with heavy metals like arsenic is a lasting legacy of the industrial age. In fact, the World Health Organization has identified arsenic as one of 10 chemicals of major concern. Minnesota, like other industrial states, had its fair share of arsenic-contaminated land, including the South Minneapolis Contamination Superfund and Perham Arsenic Superfund sites. Cleanup efforts traditionally involve the removal of contaminated soil and its long-term storage in a designated landfill. University of Minnesota scientists Michael Sadowsky and Cara Santelli are working on a sustainable alternative using hyperaccumulator plants that remove toxic metals from soil and incorporate them into plant tissue.  

“You can harvest and burn plants to collect the metal from their contents. In environmental clean-up, it’s called phytoremediation,” explains Michael Sadowsky, Director of the University of Minnesota’s BioTechnology Institute and an expert on plant-microbe interactions. Santelli, his partner on the project, is a geomicrobiologist in the Department of Earth Sciences. Together, they plan to augment the natural uptake of toxic metal using a class of soil microbe called rhizobacteria, which form symbiotic relationships with plants.

The research began in the greenhouse with a study of two plants capable of accumulating metals at a different rate. Using soil from EPA Superfund sites, the labs will measure the amount of metal absorbed by the plants when paired with microbes capable of immobilizing toxic metals in the soil or making them more accessible for natural uptake.

With that knowledge in hand, Santelli and Sadowsky will move on to local contaminated sites and test their findings in the field.

The Minnesota Pollution Control Agency and the Department of Agriculture granted access to Superfund sites during the pilot project funded with a seed grant from the MnDRIVE Environment initiative. The UMN team has partnered with Geosyntec, a national consulting firm with expertise in environmental engineering and the cleanup of contaminated metals. Geosyntec will assist in scaling successful field trials.

Seed Grant Funding

Projects like Sadowsky’s current phytoremediation research could help increase visibility for seed funding programs like MnDrive.  “Without seed funding, the ability to generate foundational data for federal funding is limited,” says Sadowsky, who also serves as Co-Director of MnDRIVE’s bioremediation initiative.

In addition to seed funding, MnDRIVE promotes collaboration with local industry and government agencies. “We’re providing research that can help drive Minnesota’s economy and protect its environmental legacy. Since its inception five years ago, MnDRIVE has played a crucial role in developing new technologies and promoting collaboration between research institutions, industry, and government.”

MaiLei Meyers is a double major in Film and Journalism with an emphasis in Strategic Communications and Public Relations at the University of Minnesota’s College of Liberal Arts and an intern in the BioTechnology Institute’s Science Communications Training Program.