Dominance-function relationships in the amphibian skin microbiome

Area of Science:

• Microbiology
• Amphibian Ecology
• Disease Ecology

Background:

• Amphibian skin harbors diverse bacterial communities.
• Some skin bacteria exhibit antimicrobial properties against the fungal pathogen Batrachochytrium dendrobatidis (Bd).
• The dominance and functional role of anti-Bd bacteria in skin microbiomes remain largely uncharacterized.

Purpose of the Study:

• To investigate the relationship between bacterial dominance and anti-Bd inhibitory function in amphibian skin communities.
• To assess how Bd prevalence and host species influence the abundance and inhibitory capacity of skin bacteria.

Main Methods:

• In vitro co-culture assays were used to quantify Bd inhibition by bacterial isolates from four amphibian species.
• 16S rRNA gene sequencing and amplicon sequencing were employed to link isolate function with relative abundance.
• Bacterial communities were analyzed from bullfrogs, Eastern newts, spring peepers, and American toads.

Main Results:

• Dominant bacteria exhibited significantly higher Bd inhibition in bullfrog and newt populations where Bd is prevalent.
• No significant difference in Bd inhibition was observed between dominant and rare bacteria in spring peeper and toad populations with low Bd prevalence.
• Inhibitory bacteria constituted over 50% of the cultured bacteria on bullfrogs and newts, compared to 25% and 37% on spring peepers and toads, respectively.

Conclusions:

• Dominant skin bacteria play a functionally important role in amphibian disease resistance.
• Bd prevalence and host species identity are critical factors shaping the amphibian skin microbiome's composition and function.
• Targeting dominant anti-Bd bacteria could offer novel strategies for amphibian disease management.