title: Antifungal Bacteria on Woodland Salamander Skin Exhibit High Taxonomic Diversity and Geographic Variability.
abstract: Diverse bacteria inhabit amphibian skin; some of those bacteria inhibit growth of the fungal pathogenBatrachochytrium dendrobatidisYet there has been no systematic survey of anti-B. dendrobatidisbacteria across localities, species, and elevations. This is important given geographic and taxonomic variations in amphibian susceptibility toB. dendrobatidisOur collection sites were at locations within the Appalachian Mountains where previous sampling had indicated lowB. dendrobatidisprevalence. We determined the numbers and identities of anti-B. dendrobatidisbacteria on 61Plethodonsalamanders (37P. cinereus, 15P. glutinosus, 9P. cylindraceus) via culturing methods and 16S rRNA gene sequencing. We sampled co-occurring species at three localities and sampledP. cinereusalong an elevational gradient (700 to 1,000 meters above sea level [masl]) at one locality. We identified 50 anti-B. dendrobatidisbacterial operational taxonomic units (OTUs) and found that the degree ofB. dendrobatidisinhibition was not correlated with relatedness. Five anti-B. dendrobatidisbacterial strains occurred on multiple amphibian species at multiple localities, but none were shared among all species and localities. The prevalence of anti-B. dendrobatidisbacteria was higher at Shenandoah National Park (NP), VA, with 96% (25/26) of salamanders hosting at least one anti-B. dendrobatidisbacterial 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-B. dendrobatidisbacteria 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 forB. dendrobatidisAnti-B. dendrobatidisbacterial species are diverse in central AppalachianPlethodonsalamanders, and their distribution varied geographically. The antifungal bacterial species that we identified may play a protective role for these salamanders.IMPORTANCEAmphibians harbor skin bacteria that can kill an amphibian fungal pathogen,Batrachochytrium dendrobatidisSome amphibians die fromB. dendrobatidisinfection, whereas others do not. The bacteria that can killB. dendrobatidis, called anti-B. dendrobatidisbacteria, are thought to influence theB. dendrobatidisinfection outcome for the amphibian. Yet how anti-B. dendrobatidisbacterial species vary among amphibian species and populations is unknown. We determined the distribution of anti-B. dendrobatidisbacterial species among three salamander species (n= 61) sampled at three localities. We identified 50 unique anti-B. dendrobatidisbacterial species and found that all of the tested salamanders were negative forB. dendrobatidisFive anti-B. dendrobatidisbacterial species were commonly detected, suggesting a stable, functional association with these salamanders. The number of anti-B. dendrobatidisbacteria 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-B. dendrobatidisbacterial community. These anti-B. dendrobatidisbacteria may serve a protective function for their salamander hosts.
authors.affiliation: Department of Biology, University of Maryland, College Park, Maryland, USA craemuletz@gmail.com.|Center for Conservation Genomics, Smithsonian Conservation Biology Institute, National Zoological Park, Washington, DC, USA.
authors.forename: Carly R
authors.identifier: http://orcid.org/0000-0001-5047-9601
authors.initials: CR
authors.lastname: Muletz-Wolz
authors.affiliation: Department of Biology, University of Maryland, College Park, Maryland, USA.|Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, California, USA.
authors.forename: Graziella V
authors.initials: GV
authors.lastname: DiRenzo
authors.affiliation: Department of Environmental Science & Technology, College Park, Maryland, USA.
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Yarwood
authors.affiliation: United States Geological Survey Patuxent Wildlife Research Center, S.O. Conte Anadromous Fish Research Laboratory, Turners Falls, Massachusetts, USA.
authors.forename: Evan H
authors.initials: EH
authors.lastname: Campbell Grant
authors.affiliation: Center for Conservation Genomics, Smithsonian Conservation Biology Institute, National Zoological Park, Washington, DC, USA.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Fleischer
authors.affiliation: Department of Biology, University of Maryland, College Park, Maryland, USA.
authors.forename: Karen R
authors.initials: KR
authors.lastname: Lips
mesh_terms: D000818:Animals; D000898:Antibiosis; D001061:Appalachian Region; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D044822:Biodiversity; D008411:Chytridiomycota / Q000254:growth & development*; D016000:Cluster Analysis; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D065928:Forests; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012867:Skin / Q000382:microbiology*; D014562:Caudata / Q000382:microbiology*
chemical_list: D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S
keywords: Batrachochytrium dendrobatidis; pathogen inhibition; salamanders; skin bacteria; symbionts