Back to Stories & News

DENVER/June 9, 2020 – Amphibian species at risk from a deadly fungal disease could be saved by a solution made from bacteria found on their own skin. Morris Animal Foundation-funded researchers at the University of Colorado, Boulder, are testing a probiotic treatment strategy in wild boreal toads to treat Batrachochytrium dendrobatidis (Bd). If successful, the treatment could help inform life-saving strategies in the race to save other amphibian species around the world.

“Amphibians are a huge, diverse group of vertebrates, so important to healthy food webs all over the globe,” said Dr. Valerie McKenzie, Associate Professor at the University of Colorado, Boulder. “It’s crucial we find a way to save them, in the most efficient way possible.”

Bd kills amphibians by infecting their skin, through which they breathe and hydrate. The fungus hardens the skin, affecting the animals’ ability to regulate air, water and electrolyte levels, resulting in death. The fungus spreads easily through water or by direct contact between individuals. Discovered in 1997, it has caused the extinction of more than 90 known amphibian species and hundreds more are in decline.

Research has identified that some native strains of bacteria on amphibian skin are able to protect captive toads from the disease. Dr. McKenzie’s team cultured bacteria from boreal toads in Colorado and found that the bacterium Janthinobacterium lividum killed the fungus. The researchers then grew the bacteria to develop a concentrated probiotic solution and applied it to Bd-afflicted boreal toads in the lab. This resulted in a 40% increase in the toads’ survival. Morris Animal Foundation is funding the team to take this information into the field to test effective ways to apply the solution to large numbers of toads.

This field-testing includes determining the best stage of the toads’ life cycle to treat them. The team is still collecting data, but preliminary results indicate that treatment may be most effective right after metamorphosis, just as the tadpoles’ skin begins to change to a more-formed toad skin. At this stage, the probiotic seems to persist longer and provide protection for the toads as they age. This is also beneficial for the researchers logistically, as these “metamorphs” cluster together in large groups.

Over the last two summers, the team has collected thousands of these individuals and soaked them in large tubs of the probiotic solution before releasing them back into the wild. The team regularly returns to the same sites to collect samples of the boreal toads to determine if the probiotic is still on their skin and if it is protecting them from Bd.

“This could be a very creative solution to an extremely serious disease problem,” said Dr. Janet Patterson-Kane, Morris Animal Foundation Chief Scientific Officer. “If it significantly increases survival, there is a good chance that this approach could be applicable to many other amphibian species.”

The boreal toad is a large subspecies of western toad that primarily lives above 8,000 feet in elevation in the wetlands of the southern Rocky Mountains. They were once common, but their populations have seen sharp declines since the 1980s, largely due to Bd.

Morris Animal Foundation, headquartered in Denver, is one of the largest nonprofit animal health research organizations in the world, funding more than $155 million in studies across a broad range of species.

About Morris Animal Foundation

Morris Animal Foundation’s mission is to bridge science and resources to advance the health of animals. Founded by a veterinarian in 1948, we fund and conduct critical health studies for the benefit of all animals. Learn more at