Antifungal Bacteria on Woodland Salamander Skin Exhibit High Taxonomic Diversity and Geographic Variability.

Diverse bacteria inhabit amphibian skin; some of those bacteria inhibit growth of the fungal pathogen Yet there has been no systematic survey of anti- bacteria across localities, species, and elevations. This is important given geographic and taxonomic variations in amphibian susceptibility to Our collection sites were at locations within the Appalachian Mountains where previous sampling had indicated low prevalence. We determined the numbers and identities of anti- bacteria on 61 salamanders (37 , 15 , 9 ) via culturing methods and 16S rRNA gene sequencing. We sampled co-occurring species at three localities and sampled along an elevational gradient (700 to 1,000 meters above sea level [masl]) at one locality. We identified 50 anti- bacterial operational taxonomic units (OTUs) and found that the degree of inhibition was not correlated with relatedness. Five anti- bacterial strains occurred on multiple amphibian species at multiple localities, but none were shared among all species and localities. The prevalence of anti- bacteria was higher at Shenandoah National Park (NP), VA, with 96% (25/26) of salamanders hosting at least one anti- bacterial species compared to 50% (7/14) at Catoctin Mountain Park (MP), MD, and 38% (8/21) at Mt. Rogers National Recreation Area (NRA), VA. At the individual level, salamanders at Shenandoah NP had more anti- bacteria per individual (μ = 3.3) than those at Catoctin MP (μ = 0.8) and at Mt. Rogers NRA (μ = 0.4). All salamanders tested negative for Anti- bacterial species are diverse in central Appalachian salamanders, and their distribution varied geographically. The antifungal bacterial species that we identified may play a protective role for these salamanders. Amphibians harbor skin bacteria that can kill an amphibian fungal pathogen, Some amphibians die from infection, whereas others do not. The bacteria that can kill , called anti- bacteria, are thought to influence the infection outcome for the amphibian. Yet how anti- bacterial species vary among amphibian species and populations is unknown. We determined the distribution of anti- bacterial species among three salamander species ( = 61) sampled at three localities. We identified 50 unique anti- bacterial species and found that all of the tested salamanders were negative for Five anti- bacterial species were commonly detected, suggesting a stable, functional association with these salamanders. The number of anti- bacteria per individual varied among localities but not among co-occurring salamander species, demonstrating that environment is more influential than host factors in structuring the anti- bacterial community. These anti- bacteria may serve a protective function for their salamander hosts.