Crisis biology: Can bacteria save bats and frogs from deadly diseases?

As populations plummet, biologists race for a solution.

  • Biologist Vance Vredenburg is one of several researchers turning to microbes in hopes of saving species threatened by disease.

    Anand Varma
  • Vredenburg swabs a Sierra Nevada yellow-legged frog to test for the presence of chytrid fungus in Kings Canyon National Park, California.

    Anand Varma
  • A little brown bat with white-nose syndrome in Greeley Mine, Vermont, March 26, 2009.

  • Dish A shows P. destructans (the fungus that causes white-nose syndrome in bats) spore growth after 21 days. Spores still grew in Dish B with unactivated R. rhodochrous bacteria. In Dish C, activated bacteria completely inhibited spore growth after 21 days. (When this experiment was conducted the, the fungus was named Geomyces destructans; it has since has been changed to Pseudogymnoascus destructans.)

    Christopher Cornelison
 

In 2007, Valerie McKenzie volunteered for a large study of human body bacteria. It was the dawn of the golden age of the microbe. Researchers were just beginning to understand how bacteria and other microbes in human intestines influence everything from obesity to allergies and infections. McKenzie, a University of Colorado-Boulder biologist, was mildly curious about her "microbiome." But she was more interested in the bacteria living on the skin of frogs and toads.

Amphibian populations worldwide are plummeting, and entire species are going extinct. The West's struggling species include boreal toads and mountain yellow-legged frogs. Invasive species and habitat degradation play a major role, but amphibians are dying even in places with good habitat. Batrachochytrium dendrobatidis, an aggressive fungus commonly known as chytrid, is often to blame.

McKenzie, who was studying the role of farmland conversion and suburbanization in the decline of leopard frogs in Colorado, suspected chytrid was also a factor. When she read a paper about a strain of bacteria found on red-backed salamanders that inhibited chytrid's growth, she began to wonder: What microbes lived on the skin of her frogs and toads? And could any of them fight chytrid?

She captured boreal toads and leopard frogs and swabbed their legs, feet and bellies at research sites near Boulder and Meeker, Colo. She took the samples to Rob Knight, a fellow CU-Boulder biologist who studies the human microbiome. In exchange for DNA analyses of the bacteria on her amphibians, McKenzie volunteered for Knight's study, handing over fecal samples and forehead, armpit and hand swabs. "I was like, 'Whatever you want, can you just run some of my frog samples?' " she laughs. "That's how I got my first data set."

McKenzie and others now hope to harness the breakthroughs of the human-microbe revolution to slow two of wildlife's most prolific – and seemingly unstoppable – modern killers: chytrid, "the worst infectious disease ever recorded among vertebrates," according to the International Union for Conservation of Nature, and white-nose syndrome, a fungal disease that has killed more than 5.7 million bats in North America since 2006.

"When you see almost 99 percent of your population perished on the (cave) floor, it's incredibly alarming," says Tina Cheng, a University of California-Santa Cruz Ph.D. student who studies white-nose syndrome. "People are desperate for solutions."

Chytrid is a cruel and efficient killer. It spreads through water and skin-to-skin contact – during mating, for instance – infecting amphibians' skin, reducing their ability to absorb water and disrupting electrolyte levels enough to cause major organ failure. In weeks, it can obliterate populations.

Scientists suspect the disease is so devastating because most amphibians have never encountered this strain of the fungus before. Humans likely transported it around the globe in the pet trade, on American bullfrogs, whose legs are a delicacy, or on African clawed frogs, which doctors used for pregnancy tests until the 1970s. (The frog laid eggs when injected with a pregnant woman's urine.) Scientists first linked mass mortalities to chytrid in Australia and Central America in the late 1990s. It's since driven more than 200 species to collapse or extinction and colonized every continent except Antarctica.

High Country News Classifieds
  • WESTERN NATIVE SEED
    Native plant seeds for the Western US. Trees, shrubs, grasses, wildflowers and regional mixes. Call or email for free price list. 719-942-3935. [email protected] or visit...
  • COMMUNITY ORGANIZER
    Western Colorado Alliance for Community Action is seeking two full time community organizers to join our team. Positions can be based in Garfield County, Montrose...
  • EXECUTIVE DIRECTOR
    Join our team as the Association's Executive Director. Working closely with the Board of Directors, take ANWS to the next level of professionalism by managing...
  • FRIENDS OF CEDAR MESA DEVELOPMENT DIRECTOR
    Friends of Cedar Mesa is hiring a Development Director who will have the overall responsibilities of leading our fundraising programs and reports directly to our...
  • WATER RIGHTS/ADJUDICATION BUREAU CHIEF
    Job Overview: Working to support and implement the Department's mission to help ensure that Montana's land and water resources provide benefits for present and future...
  • CLIMATE CHANGE COORDINATOR
    The Greater Yellowstone Coalition is seeking a Climate Change Coordinator to play a lead role in shaping our programs to make the Greater Yellowstone Ecosystem...
  • EXECUTIVE DIRECTOR
    Executive Director Position Announcement POSITION TITLE: Executive Director ORGANIZATION: Friends of Cascade-Siskiyou National Monument REPORTING TO: Board of Directors EMPLOYMENT TYPE: Part-time - Full-time, based...
  • HEALTHY CITIES PROGRAM DIRECTOR
    The Healthy Cities Program Director leads and manages the Healthy Cities Program for the Arizona Chapter and is responsible for developing and implementing innovative, high...
  • CONSERVATION PROGRAM MANAGER
    Grand Staircase Escalante Partners (GSEP) Conservation Programs Manager Job Opening Our Mission: Honoring the past and safeguarding the future of Grand Staircase-Escalante National Monument through...
  • ASSOCIATE DIRECTOR
    Grand Staircase Escalante Partners (GSEP) Associate Director Job Posting Our Mission: Honoring the past and safeguarding the future of Grand Staircase-Escalante National Monument through science,...
  • UNIQUE, ENERGY-EFFICIENT HOME ON ACREAGE NEAR MOSCOW, IDAHO
    Custom-built energy-efficient 3000 sqft two-story 3BR home, 900 sqft 1 BR accessory cottage above 2-car garage and large shop. Large horse barn. $1,200,000. See online...
  • OUTDOOR ADVENTURE BUSINESS FOR SALE
    Missoula Outdoor Learning Adventures (MOLA) - established and profitable outdoor adventure & education business in Missoula, Montana. Summer camp, raft & climb guide, teen travel,...
  • OJO SARCO FARM/HOME
    A wonderful country setting for a farm/work 1350s.f. frame home plus 1000 studio/workshop. 5 acres w fruit trees, an irrigation well, pasture and a small...
  • STEWARDSHIP COORDINATOR
    Join Skagit Land Trust (the Trust), a not-for-profit conservation organization based in Mount Vernon, Washington, and help protect land for people and wildlife. Skagit Land...
  • 2022 SEASONAL SCIENCE EDUCATOR
    The Mount St. Helens Institute Science Educator supports our science education and rental programs including day and overnight programs for youth ages 6-18, their families...
  • POLICY DIRECTOR
    Heart of the Rockies Initiative is seeking a Policy Director to lead and define policy efforts to advance our mission to keep working lands and...
  • CHIEF FINANCIAL OFFICER
    Self-Help Enterprises seeks an experienced and strategic CFO
  • CONSERVATION SPECIALIST - LAND PROTECTION FOCUS
    View full job description and how to apply at
  • RIVER EDUCATOR & GUIDE
    River Educator & Guide River Educator & Guide (Trip Leader) Non-exempt, Seasonal Position: Full-time OR part-time (early April through October; may be flexible with start/end...
  • LAND AND WATER CONSERVATION DIRECTOR
    The Land and Water Conservation Director is a full-time salaried position with the Mountain Area Land Trust in Evergreen, CO. The successful candidate will have...