Killer White Nose Syndrome Fungus is Resilient,'Grim' Outlook for Hibernating Bats

The fungus that causes bats to develop the deadly white nose syndrome has proven to be a highly capable and resilient organism that seems to be unstoppable, according to new research published in the journal PLOS ONE, which reports there is little, if anything, that can be done to stop the organism from spreading further and lingering in bat caves indefinitely.

The fungus, Pseudogymnoascus destructans (recently renamed from Geomyces destructans), grows on hibernating bats thriving in the low temperatures brought on by the winter months, rousing the bats from their slumber and causing them to burn vital energy stores intended to last them through the winter. With their energy depleted, the bats are weakened and become susceptible to starvation and other illnesses.

A colony infected with white nose syndrome is almost certainly doomed. Earlier this year a study of a bat colonies in Bucks County, Pa. revealed that once the fungus infected a cave home to 10,000 bats, only 23 made it through the winter, and half of the survivors were infected with white nose syndrome.

An estimated 5.5 million bats have died in the United States and Canada after becoming infected with white nose syndrome since it was first reported in North America in New York during the winter of 2006-2007.

New research on the deadly fungus out of the University of Illinois at Urbana-Champaign suggests that P. destructans can make a meal out of just about any carbon source found in the bat caves. The find spells bad news for bats.

"It can basically live on any complex carbon source, which encompasses insects, undigested insect parts in guano, wood, dead fungi and cave fish," said Daniel Raudabaugh, a graduate student who led the research. "We looked at all the different nitrogen sources and found that basically it can grow on all of them. It can grow over a very wide range of pH; it doesn't have trouble in any pH unless it's extremely acidic."

Raudabaugh said that as the fungus spreads, it creates an environment that degrades the structure of keratin, the main protein in skin. By breaking down the keratin on the skin of bats, it leaves the hibernating mammals more susceptible to a host of other infections.

The fungus can subsist on proteins and lipids in the bats' skin, as well as glandular secretions, giving an unobstructed path of growth.

Other than temperatures exceeding 20 degrees Celsius, the only other thing the researchers found that was obstructive to the fungus was it's ability to absorb water from natural surfaces like dry wood. But in the presence of fat cells on the bats' skin, the fungus can draw water uninhibited.

"All in all the news for hibernating bats in the U.S. is pretty grim," said mycologist Andrew Miller, who advised Raudabaugh during the study.

"When the fungus first showed up here in Illinois earlier this year we went from zero to 80 percent coverage in a little more than a month," Miller said.

While previous studies have detailed the fungus' genome and what happens to infected bats, this research is reportedly the first to take an in-depth look at the basic biology of the killer fungus.

"Dan found that P. destructans can live perfectly happily off the remains of most organisms that co-inhabit the caves with the bats," Miller said. "This means that whether the bats are there or not, it's going to be in the caves for a very long time."