Researchers race to slow a disease that could wipe out some bat species

Christine Salomon photographs bats on a wall in the Soudan Mine.
University of Minnesota scientist Christine Salomon photographs bats on a wall in the Soudan Mine on Monday, June 19, 2017.
Dan Gunderson | MPR News

The fungal disease called white-nose syndrome has killed millions of bats since it was first discovered in North America 10 years ago, but University of Minnesota scientist Christine Salomon hopes to find a treatment deep in the cold damp shafts of the Soudan Mine.

"We're just looking at the basic biology of the pathogen, trying to understand how it grows and expands over time," explains Salomon.

The disease reached Minnesota two years ago and has killed thousands of bats the past two winters at the underground mine not far from Ely. Mining stopped in the 1960s, but the mine was turned into a state park that attracts tourists in the summer and houses thousands of hibernating bats in the winter.

Salomon's experiments take place 900 feet below the surface. To reach them, she takes an elevator, wearing a white decontamination suit, a hard hat and a headlamp.

"Bats come in on level 12 and hibernate here," she says as she steps from the elevator.

A few bats hang on the walls here and dead bats litter the floor. But by June most have left the mine for nearby forests where they will raise young before returning next fall.

Little brown bats and northern long-eared bats live here. Both species are hit hard by white-nose syndrome. The northern long-eared bat is listed as threatened under the federal endangered species act.

U of M scientist Christine Salomon checks fungus samples in the mine.
University of Minnesota scientist Christine Salomon checks fungus samples in the Soudan Mine on Monday, June 19, 2017.
Dan Gunderson | MPR News

Salomon walks down a dark tunnel to an overturned milk crate that she moves to reveal several small plastic bags. The bags are filled with soil from the mine floor, and the bat killing fungus, pseudogymnoascus destructans. The bags have microscopic holes so air and water can get in, but the fungus can't escape.

She'll return in about three months for more samples.

Dozens of researchers across the country are trying to find a way to defeat pseudogymnoascus destructans.

Some are developing vaccines to protect bats. Others are testing pesticide treatments to kill the fungus in caves. Salomon is one of a few working on finding ways to stop the fungus from growing and reproducing by using natures evolutionary power.

She's isolated hundreds of bacteria and fungi from the Soudan mine and from caves in Minnesota. In nature these micro-organisms are always competing for survival. One of the ways they survive is by evolving to inhibit growth or reproduction of other organisms. So Salomon tests samples in the lab to find out which ones might slow or stop pseudogymnoascus destructans.

"Right now we have over 100 bacteria and fungi that can inhibit the growth of P. destructans on a petri dish, in the lab. (But that's a) pretty unnatural environment," she says. "What we'd really like to be able to do is test them individually in the Sudan iron mine. But no one's ever done that."

A bat illuminated by a headlamp clings to the walls deep underground.
A bat illuminated by a headlamp clings to the walls deep underground in the Soudan Mine in northeastern Minnesota on Monday June 19, 2017.
Dan Gunderson | MPR News

There are few successful examples of treating disease in wildlife. And how do you treat bats? Let's say Salomon finds a bacteria that stops pseudogymnoascus destructans cold. The next challenge would be growing large amounts of the bacteria and somehow spreading it through parts of the mine where bats hibernate.

Typically, research like this would take years. But this is more like emergency science.

"I would normally like just really figure out every detail and be really confident that this is exactly how I want to test it," said Salomon. "But if the bats are dying every year, then I don't have time."

So, instead of a deliberate focus on learning how the fungus grows in the Soudan mine and in caves, followed by years of testing and peer-reviewed publishing, Salomon plans to start testing the most promising bio-control before she even finishes the basic research.

It's possible this research could lead to an experimental treatment for white-nose in a couple of years, says Jeremy Coleman, who leads the national white nose initiative for the U.S. Fish and Wildlife Service.

Coleman doesn't expect a silver bullet cure, but he says researchers are casting a wide net hoping for multiple treatments.

White nose syndrome has killed thousands of bats in the past two years.
Bats illuminated by a headlamp cling to the walls deep underground in Soudan mine.
Dan Gunderson | MPR News

"We're trying to do the best we can with what we've got to move things along as quickly as possible because the bats, many of these species, are losing the battle against white-nose syndrome," said Coleman who lists the northern long-eared bat found in Minnesota as of special concern.

The challenges are many. Bats hibernate in many different environments. A treatment that works in a mine might not work in a cave. The treatment can't cause significant environmental damage.

A biological control could be a good short term solution, said Coleman because treating bats with a microbe already found in the mine would likely limit damage to the environment. And it might be one way to slow the growth of pseudogymnoascus destructans. Coleman says research indicates even reducing the level of fungus bats are exposed to while hibernating improves the odds of survival.

"And even if it's to improve survival in some small percentage, that could be the difference in bats being able to survive in the presence of this disease, or facing extinction," said Coleman.

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