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Updated: Sep 19, 2025
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Isolation and Identification of Bacterial Strains from Skin of Terrestrial Amphibians
Published on: June 17, 2025
709
Skin Defenses and Host-Environment Microbiome Interactions in Spotted Salamanders
Julian Urrutia-Carter1, Joseph D Madison1,2, J Adam Frederick3
1Center for Conservation Genomics, Smithsonian's National Zoo and Conservation Biology Institute, Washington, DC 20001, USA.
Integrative and Comparative Biology
|June 16, 2025
Summary
Spotted salamanders show no signs of emerging infectious diseases like Bd or Bsal. Their skin mucus and microbiome do not appear to defend against Bd, suggesting other resistance mechanisms are at play.
Area of Science:
- Amphibian disease ecology
- Microbiome research
- Biodiversity conservation
Background:
- Emerging infectious diseases pose a significant threat to amphibian biodiversity globally.
- Batrachochytrium dendrobatidis (Bd), Batrachochytrium salamandrivorans (Bsal), and ranavirus are key pathogens affecting amphibian populations.
- The Appalachian Mountains are a biodiversity hotspot for salamanders, with Bd and ranavirus present and Bsal emergence a potential threat.
Purpose of the Study:
- To investigate the mechanisms of disease resistance in spotted salamanders (Ambystoma maculatum) against Bd, Bsal, and ranavirus.
- To test the hypothesis that spotted salamander mucus and skin microbiomes provide defense against Bd.
- To determine pathogen prevalence and characterize skin/environmental microbiomes during the breeding season.
Main Methods:
- Non-invasive sampling of spotted salamanders and surrounding water at two breeding pools.
- Detection assays for Bd, Bsal, and ranavirus.
- In vitro testing of salamander mucus for antifungal activity against Bd.
- 16S rRNA gene sequencing to analyze skin and environmental microbiome diversity and composition.
Main Results:
- No Bd, Bsal, or ranavirus were detected in sampled spotted salamanders.
- Salamander mucus did not inhibit Bd growth in vitro.
- Anti-Bd bacteria were found in low abundance in the salamander skin microbiome.
- The salamander microbiome shared some bacteria with the environment and selected for rare taxa, but their role in pathogen defense remains unclear.
Conclusions:
- The skin mucus and microbiome of spotted salamanders do not appear to be the primary mechanisms conferring resistance to Bd.
- Alternative resistance mechanisms, potentially involving internal immune responses like gene expression, may be responsible for Bd defense in this species.
- This study highlights the complexity of amphibian disease susceptibility and the need for further research into host-pathogen interactions.
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