How do you test salamanders for good and bad microbes?
We looked for salamanders on the Smithsonian Conservation Biology Institute’s campus in Front Royal, Virginia. This area has at least nine native species, but we concentrated on four for this study: the red spotted newt, the red-backed salamander, the two-lined salamander and the dusky salamander.
When we catch a salamander, we rinse them off in a bath of clean water to remove any excess dirt or debris. Then, we take a cotton swab and collect a sample of mucus from their skin. Using that swab, we can extract DNA from the sample and test for chytrid and other viral pathogens that could potentially make the animals sick.
We can also look for good microbes and bacteria. Both salamanders and frogs secrete peptides from their skin that have antimicrobial properties, and they have bacteria on their skin that produces metabolites. We use this compilation of molecules in their skin secretions as a proxy to determine how susceptible they are to Bd and Bsal.
Interestingly, when we grow the good microbes and bacteria in the same culture as the bad fungus and pathogens, a microscopic “duel” ensues. Sometimes, the good microbes and bacteria are able to kill these pathogens in culture form. It is a fight to the death—in a petri dish.