NAU’S MGGen Lab Tracks Lethal Bat Fungus

In the eastern United States and Canada bats have been dying by the hundreds of thousands—a result of a fungal disease called white-nose syndrome (WNS) caused by the fungus Geomyces destructans (Gd). At Northern Arizona University (NAU), Dr. Jeff Foster, Associate Director of NAU’s Center for Microbial Genetics and Genomics (MGGen), and his team of five undergraduate students and Postdoctoral Researcher Kevin Drees are tracking the spread of Gd using genetics.

Although the disease was first discovered in a New York cave during the winter of 2006, its exact origins are still a mystery. Since then, the fungus has spread into 19 U.S. states and four Canadian provinces, killing greater than 5.5 million bats. Because of the far-reaching importance of bats for pollination and pest control in agriculture and forestry, NAU’s research has both national and international significance.  “Bats provide ... major ecosystem services. We don’t pay the bats to do this, [but] they go out there and eat millions and millions of tons of insects that have direct effects on things like agriculture and mosquito populations. The likelihood is that without bats eating all these insects, we’re going to be drastically affected,” notes Foster.

“Bats provide ... major ecosystem services. … They go out there and eat millions and millions of tons of insects that have direct effects on things like agriculture and mosquito populations.”

The white, cold-loving fungus, which most scientists suspect was unintentionally transported from Europe, attacks bats when they are hibernating in caves in the winter. The fungus grows on their faces and wings—giving the appearance of a “white nose”—and causes them to awaken more often and sooner than uninfected bats do. Infected bats tend to freeze or starve to death due to a lack of fat reserves.

The Gd project

The Gd project, which began in 2010, has two key components.

         1. Detecting Gd in various samples. Researchers in the MGGen lab receive from numerous collaborators swabs of bat skin, walls of caves, and dirt samples, as well as bat feces to “look for the presence of the fungus down to forensic levels,” says Foster. Detection allows them to see how Gd interacts with its environment and how it is spreading so that, theoretically, one does not need a bat to know if Gd has spread to a given cave. This method shows that Gd may have different effects on different bat species. For example, the little brown bat (Myotis lucifugus) appears to have both the highest amount of Gd on infected bats and the highest mortality rate. By being able to detect exact amounts of the fungus on samples, researchers can begin to understand whether or not there is a relationship between the quantity of Gd and mortality.     

 Since 2010, researchers at NAU have tested more than 5,000 samples at least two or three times.  “Having lots of collaborators who can assist with things like taking samples and analyses is imperative,” says Foster.

        2. Examining Gd genetics to determine the fungus’s origin and likely routes of dispersal. By sequencing genomes, the team can identify relationships between isolates (pure strains) of the fungus, Foster says, “We will be very happy when and if we find identical isolates from Europe.” He asserts the genetic similarities between strains “strongly suggest a single, recent introduction of the fungus [to the United States, from Europe].”

So how does one account for genetic differences between American and European isolates of the fungus if they most likely come from the same place?

Students help solve the mystery 

The Gd fungus has been in Europe for hundreds— if not thousands—of years, and therefore had time to become genetically diverse there. This makes finding a European match for the American Gd fungus a trickier task. “If we find the origin, the genetics should be pretty conclusive,” he says. For this sleuthing part of the research, Foster and his team have sequenced 30 genomes in their entirety and sequenced portions of 70 Gd genomes.

Sabrina German, an NAU senior and biomedical science major, has been working on this project since it began. She spends five days a week in the lab doing genetic extractions, and often analyzes Gd assay results from home. German views this research as an educational opportunity: “Working in the lab and going to school at the same time definitely has its challenges, but things I’ve learned in class I am now able to directly apply to what I’m doing here and vice versa.” German added that she enjoys contributing new knowledge to a subject that is still so vastly unknown.

As biologists across the globe seek to understand Gd and the sudden, widespread mortality it is causing in North American bats, researchers from NAU’s own MGGen lab are adding pieces to this consequential puzzle. They hope to help prevent future devastation of North America’s bat populations. 

--Emily Litvack