# Novel antimicrobial peptides and peptide-microbiome crosstalk in Appalachian salamander skin

## TL;DR

This study identifies new antimicrobial peptides in salamander skin and explores their interactions with skin microbes and pathogens.

## Contribution

Discovery of 200+ candidate antimicrobial peptides and their role in shaping salamander skin microbiomes and inhibiting pathogens.

## Key findings

- Candidate AMPs were detected in all individuals, with Cathelidicins being most common via transcriptomics.
- AMPs were found in 34% of individuals via proteomics, with Kinin-like peptides most common in E. bislineata.
- Two Cathelicidins inhibited human pathogens like Acinetobacter baumannii and Escherichia coli.

## Abstract

Using multi-omics tools, we discovered new antimicrobial peptides (AMPs) and examined AMP-microbial interactions in three Appalachian salamander species (Plethodon cinereus, Eurycea bislineata and Notophthalmus viridescens). We conducted skin transcriptomics (n = 13) and proteomics (n = 91) to identify 200+ candidate AMPs. With candidate AMPs, we identified correlations with skin microbiomes and synthesized 20 peptides to challenge against pathogens of amphibians (Batrachochytrium dendrobatidis: Bd) and humans (ESKAPEE). Using transcriptomics, candidate AMPs were detected in all individuals with Cathelidicins being most common. Using proteomics, AMPs were found in 34% of individuals (31/91)—predominately E. bislineata—with Kinin-like peptides being most common. Candidate AMP composition generally predicted skin bacterial composition, suggesting that AMPs influence host-microbial symbioses. Crude and synthesized peptides showed limited activity against Bd. Two synthesized Cathelicidins (Pcin-CATH3 and Pcin-CATH5) inhibited human pathogens, Acinetobacter baumannii, Pseudomonas aeruginosa and Escherichia coli. Our findings inform the potential usage of AMPs in conservation and translational applications.