Engineering a self-cleaning environment

Engineering a self-cleaning environment

UMN researchers create self-cleaning Biohubs to mitigate the impact of pollutants in Minnesota’s waterways

by Lauren Holly

Minnesota’s Iron Range is dotted with active and abandoned mining sites. Left untreated, runoff from these sites can flow into the environment and release heavy metals and organic pollutants, ultimately endangering wildlife and threatening human health.

But what if we could engineer the environment to clean itself? With support from the MnDRIVE Environment initiative, researchers in the BioTechnology Institute’s Schmidt-Dannert lab are developing Biohubs using genetically engineered proteins capable of breaking down heavy metals and removing toxins from mine drainage and other industrial sites.

Biohubs take advantage of a protein’s natural tendency to self-assemble into stable shell-like structures. Their porous surface converts harmful metals and organic pollutants into non-toxic components.

Based on similar structures found in nature, the lab’s model Biohub converts toxic mercury compounds into a form that can be released safely in the environment. The process relies on modified proteins that bind toxins while enzymes, small proteins capable of catalyzing biochemical reactions, convert mercury to its inert elemental form. The system is “self-cleaning” because the enzymes remain active inside the Biohub until it encounters the next metal, and restarts the process.

On-site, the Biohubs are placed in glass or metal columns that act as a filtration system; contaminated water enters through one end of the column and exits at the opposite end of the column free of toxins.

Using enzymes to clean the environment has advantages. They are versatile and leave no toxic residue, but enzymes found in nature are not always stable, and Schmidt-Dannert’s team needed a way to protect and stabilize the proteins. Enter Minnepura Technologies; a biotech startup co-founded by University of Minnesota Professors Alptekin Aksan and Lawrence Wackett. Minnepura specializes in the development of biocomposite materials designed to encapsulate and protect proteins. Minnepura and will encase the Biohubs in an easily adaptable, light-weight silica that supports the structure over time.

“Initial studies will focus on remediation of heavy metals from mine drainage, but the system could also be applied to clean up of pesticide-contaminated soil or water near agricultural land,” explained Maureen Quin, a lead researcher on the project.

Schmidt-Dannert believes engineered proteins hold considerable potential as a platform technology for sustainable bioremediation. “If we can get this to work with organic compounds, this solution could be very versatile and able to convert a variety of different pollutants.” In states like Minnesota trying to balance the competing demands of industry and environmental stewardship, Biohubs may help the environment clean itself.

Lauren Holly is an intern in the BioTechnology Institute’s Science Communications Training Program.

Minnesota Lakes in Peril

Minnesota Lakes in Peril

UMN researchers use DNA technology to track fecal contamination in Minnesota waters

View the full infographic here.

By: Rachel Zussman
Infographic by: Kate Johns

Imagine your next summer vacation: boating, fishing, or swimming in Minnesota lake country. After months of anticipation, you arrive at the lake to find the beaches closed and the water contaminated by fecal bacteria. Unfortunately, it’s not an isolated occurrence. According to the Minnesota Pollution Control Agency, 40% of Minnesota’s lakes and streams are impaired, with fecal contamination becoming a growing concern. A team led by University of Minnesota microbiologist Michael Sadowsky hopes to provide public health officials with better tools to track the source of contamination and assess the public health risk.

Fecal contamination has been a national issue for decades. In 1977, the US government adopted the Clean Water Act using coliform bacteria (and later the bacterium E. coli) as an indicator for fecal contamination of waterways. Commonly found in the intestinal tract of the warm-blooded animals, E. coli in the water suggested the possible presence of other fecal pathogens, and forced officials to close beaches out of an abundance of caution. As new research indicated that E. coli could survive in nature outside the gut, its value as an indicator of water quality waned. Researchers now focus on the source of bacteria to better assess the public health risks and eliminate contamination at the source.

Initially, Sadowsky’s team relied on a technique known as DNA fingerprint analysis to identify the source of fecal contamination. “We would go into the environment and collect ‘fingerprints’ of individual bacteria,” explains Sadowsky. “These ‘fingerprints’ would then be matched with E. coli bacteria obtained from feces of 17 animal species.” Though more accurate than older methods, DNA fingerprinting only worked about 75% of the time.

Improvements in DNA sequencing technology now allow Sadowsky’s team to analyze fecal samples from a large number of animal species. Using SourceTracker, a software program developed by the UMN’s Knights Lab, the team can compare the distribution of organisms in water samples with those found in the animals.

So far, Sadowsky has successfully identified contamination coming from a few sources. But since contamination often comes from both humans and animal origin, making the source of the contamination harder to identify and remediate.

Though wildlife and agriculture add to the problem, Sadowsky believes that both point and non-point source microbial contamination are symptoms of urbanization. “We have cities with millions and millions of people,” he adds. “Every time you flush a toilet, that water has to go somewhere.”

As the technology continues to improve, Sadowsky hopes the research will help inform public policy. “I want to work with decision-makers to establish water quality standards based on the source of contamination.”

Health risks depend on both the source and the level of fecal contamination. With better tools at their disposal, policymakers can continue to protect the public while residents and tourists continue to enjoy summer days on Minnesota’s 10,000 lakes.

Rachel Zussman is a Biology, Society, and Environment major at the University of Minnesota’s College of Liberal Arts and an intern in the BioTechnology Institute’s Science Communications Training Program.

Katie Johns is a recent graduate with a major in Graphic Design from the University of Minnesota’s College of Design, and an alumni of the BioTechnology Institute’s Science Communications Training Program

Saving Little Brown Myotis

Saving Little Brown Myotis

Can native microbes help protect Minnesota’s bat population from the deadly white-nose bat syndrome?

By: Kelley Hosieth
Infographic: Megan Smith

View full infographic here.

Pseudogymnoascus destructans (PD), the fungus responsible for white-nose syndrome (WNS), was first detected in upstate New York in 2007. Over the past decade, that state’s bat populations have declined by 90% and the fungus has since spread across the country, including Minnesota.

To combat the spread of WNS, the University of Minnesota’s Christine Salomon and her research team have been working in the Soudan Mine, an old iron mine in northern Minnesota. They hope to find native fungi or bacteria that act as a biological control to stop PD from causing more ecological damage.

“A biological control is a good solution because it spreads like the disease and can be dispersed into the environment,” says Michael Wilson, a postdoc in the Salomon lab. “That sounds like a simple plan, but nothing like this has ever been done before.”

The terrain produces one of the greatest challenges for scientists. Bats are widely dispersed in dark caves with uneven terrain. Sometimes, researchers don’t know how large the caves actually are.

WNS spreads when infected bats come into contact with healthy bats. The fungus infects bats’ skin, which causes them to wake up more frequently from hibernation. Once awake, the bats quickly burn their stored fat, and they starve.

Wilson is working on the basic biology of P. destructans to help guide the implementation of a biological control strategy. “If it only affects bats, and all the bats die, then the environment will be disease-free,” Wilson says. “But if the pathogen is self-sustaining, the environment is contaminated indefinitely.”

Some researchers have argued for no intervention to save little brown bats, (Myotis lucifugus) and their larger cousins, northern long-eared bats (Myotis septentrionalis). They believe that resources should go to saving the remaining 10% of bat populations that survived infection.

“It would require a big investment in protecting remnant populations. So you can either intervene now or use all your resources to try and help the remnant populations survive– even if we don’t understand why they survive,” Wilson said.

Salomon, a member of the University’s BioTechnology Institute continues to work on white-nose syndrome, testing hundreds of fungal and bacterial isolates that have the potential to act as a biological control. Once the lab identifies the most promising strains, they’ll begin preliminary testing of control agents on surfaces in the field.  They are hopeful they have an effective method to help bats in Minnesota and across the country. Although they would like to spend many more years refining and testing their biocontrol candidates in the lab, time is running out due to the precipitous decline in bat populations every winter.  “There are so many questions that cannot be answered until we do field trials,” says Salomon. “There are risks that come with it but that’s part of our work.”