Frog Microbes May Help Fight Disease

Commensal skin bacteria adjusted their community structure when frogs were exposed to chytrid fungus in a recent study.

Oct 7, 2015
Karen Zusi

VIRGINIA TECHChytridiomycosis, a skin disease caused by the chytrid fungus Batrachochytrium dendrobatidis, currently threatens approximately 500 amphibian species worldwide. Researchers led by a team from Virginia Tech demonstrated that the composition of microbes on bullfrogs’ skin can indirectly affect the disease symptoms; the results were published today (October 7) in PLOS ONE.

Researchers at Virginia Tech and their colleagues collected 60 juvenile bullfrogs (Lithobates catesbieanus) from a pond in Virginia where the fungus had previously been detected. The team sampled the frogs’ naturally occurring skin microbes and randomly assigned them to one of six experimental groups: the frogs’ skin microbiomes were either reduced with antibiotics, augmented with a probiotic, or left alone. The bullfrogs were then either exposed to the fungus or used as a control over the 42-day experiment.

When the researchers analyzed the resulting microbial communities on the frogs, they discovered that simply augmenting or reducing the skin microbiome did not affect the intensity of the fungal infection—but the antibiotic-treated frogs grew less than their counterparts when exposed to the fungus. The microbes differed in composition among the exposed frog groups, depending on their skin treatment. “The normal microbiota of bullfrogs is important for disease outcome, and potentially host fitness,” the authors concluded in their report.

“Factors that contribute to microbial community assembly and maintenance on amphibian skin, including host factors, habitat, diet, and the available microbial species pool, may ultimate influence disease dynamics,” study coauthor Lisa Belden of Virginia Tech said in a press release.