Credit: Joel Sartore/Natl Geographic/Getty

Treatment with a skin microbe protects captive toads against a lethal fungal infection.

Valerie McKenzie at the University of Colorado Boulder and her colleagues compared the skin microbiomes of endangered boreal toads (Anaxyrus boreas; pictured) reared in captivity with hose of wild ones. They found that the diversity of bacterial strains that inhibit the fungal pathogen Bd (Batrachochytrium dendrobatidis) was greatly reduced on the captive toads, and that these animals lost the protective microbes over time. As a result, after nearly eight months in captivity, all toads exposed to the fungus died. In a second experiment, inoculating exposed amphibians with a Bd-inhibiting microbe increased the animals' survival by 40%.

Long-term captivity reduces toads' exposure to beneficial environmental microbes that protect them against Bd and other pathogens, the authors say.

Proc. R. Soc. B 283, 20161553 (2016)