This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The bacteria living on frogs' skin could play a vital role in protecting the animals from a deadly fungal disease. A team of researchers led by Penn State scientists found that frogs' natural skin bacteria can help them fight disease and improve their chances of survival.
The study, published in the journal Animal Microbiome, found a causal relationship between the natural bacteria inhabiting frogs' skin, called the skin microbiome, and their ability to survive a deadly fungal pathogen—a major threat to wild frogs and other amphibians worldwide. "This is one of the clearest demonstrations that a host's natural skin bacteria can be a frontline defense against a pathogen that has devastated amphibian populations globally," said Gui Becker, associate professor of biology in the Penn State Eberly College of Science and senior author of the paper. "One of the key messages from this study is that it's not simply the diversity of these bacteria—referred to as the skin microbiome—that matters, but the protective function of these bacteria." The pathogen is called a chytrid fungus (Batrachochytrium dendrobatidis or Bd); it causes skin damage in amphibians and eventually heart failure.
To test how skin-associated bacterial communities can protect tropical frogs against disease, the research team conducted a lab experiment in Brazil focusing on two frog species: Haddadus binotatus and Ischnocnema henselii. The experimental design allowed them to understand the effect of microbiome suppression on disease risk in these amphibians. Throughout the study, researchers used DNA sequencing to identify the bacteria living on each frog's skin and compare how these bacterial communities predict host health.
The team found that one species, H. binotatus, naturally tolerated the fungus when its healthy skin microbiome could help protect it from infection. When that protective community of bacteria was suppressed with antibiotics, the frogs became more likely to develop signs of disease. In contrast, the second species, I. henselii, remained highly susceptible to the fungus regardless of skin microbiome suppression, indicating that different frog species rely on different strategies to defend themselves against the disease.
"We see this striking contrast: one species has one of the highest prevalences of the fungus, while the other has no infections in the wild. That made them a perfect pair to understand what role the microbiome might be playing," said Laura Schuck, a doctoral student in the Intercollege Graduate Degree Program in Ecology at Penn State and lead author of the study. "For years we knew that the tropical frog H. binotatus rarely became infected with the fungus in the wild, but we didn't know why.
This study moved us from correlation to experimental evidence that the microbiome really is important against this disease." Discover the latest in science, tech, and space with over 100,000 subscribers who rely on Phys.org for daily insights. d research that matter—daily or weekly. Developing an understanding of specific protective bacterial mechanisms was painstaking work, the researchers said. Schuck cultured roughly 700 strains of bacteria from the frogs' skin, grew each one in culture, and exposed the chytrid fungus to their chemical byproducts, tracking fungal growth over a week.
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