Genre
- Journal Article
Background:
Cutaneous bacteria inhabiting the skin of boreal toads (Anaxyrus (Bufo) boreas boreas) and columbia spotted frogs (Rana luteiventris) from Grand Teton National Park were isolated and identified using their 16S SSU rRNA gene sequence. We also used a culture-independent method, Terminal Restriction Fragment Length Polymorphism (TRFLP) analysis of the 16S SSU rRNA gene sequence, to characterize and compare the bacterial microbiota of these two amphibian species within and between different collection sites in Grand Teton National Park, Wyoming, USA.
Results: Bacterial isolates belonged to 5 major phylogenetic lineages: the Actinobacteria, the Bacteroidetes/Chlorobi Group, and the Alpha-, Beta-, and Gamma-Proteobacterial lineages. TRFLP analyses showed a high species richness between sites and between amphibian species, as well as a significant amount of diversity. All three measures of diversity used (Margalef Species Richness, the Shannon Index, and the Simpson Index) were higher for frog samples than toad samples, but varied between sites. Additive Main effects and Multiplicative Interaction (AMMI) analysis of the TRFLP results showed more variability in the 3' fragments than in the 5' fragments of the 16S SSU rRNA gene sequences amplified from metagenomic DNA extracted from amphibian skin surface samples. Furthermore, within the 3' fragments one site was shown to be significantly different than the other four sites by AMMI analysis.
Conclusions: This study illustrated the extensive phylogenetic diversity of microorganisms present on the skin of frogs and toads present in GTNP. The identification of some of the bacterial isolates present as belonging to lineages known to produce antifungal or antibiotic compounds (thereby enabling microbial antagonism) forms the basis for a plausible hypothesis for the disease resistance of amphibians to Batrachochytrium dendrobatidis in GTNP.
Language
- English