Pesticides Could Alter Amphibian Skin Microbiomes and the Effects of Batrachochytrium dendrobatidis

Individual differences in host phenotypes can generate heterogeneity in the acquisition and transmission of microbes. Although this has become a prominent factor of disease epidemiology, host phenotypic variation might similarly underlie the transmission of microbial symbionts that defend against pathogen infection. Here, we test whether host body size and behaviour influence the social acquisition of a skin bacterium, Janthinobacterium lividum , which in some hosts can confer protection against infection by Batrachochytrium dendrobatidis , the causative agent of the amphibian skin disease chytridiomycosis. We measured body size and boldness (time spent in an open field) of green frog tadpoles and haphazardly constructed groups of six individuals. In some groups, we exposed one individual in each group to J. lividum and, in other groups, we inoculated a patch of aquarium pebbles to J. lividum . After 24 h, we swabbed each individual to estimate the presence of J. lividum on their skin. On average, tadpoles acquired nearly four times more bacteria when housed with an exposed individual compared to those housed with a patch of inoculated substrate. When tadpoles were housed with an exposed group-mate, larger and ‘bolder’ individuals acquired more bacteria. These data suggest that phenotypically biased acquisition of defensive symbionts might generate biased patterns of mortality from the pathogens against which they protect.

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Phylogenetic investigation of skin sloughing rates in frogs: relationships with skin characteristics and disease-driven declines

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2018.2378 ◽

2019 ◽

Vol 286 (1896) ◽

pp. 20182378 ◽

Cited By ~ 4

Author(s):

Michel E. B. Ohmer ◽

Rebecca L. Cramp ◽

Craig R. White ◽

Peter S. Harlow ◽

Michael S. McFadden ◽

...

Keyword(s):

Batrachochytrium Dendrobatidis ◽

Phylogenetic Signal ◽

Interspecific Variation ◽

Phylogenetic Position ◽

Turnover Rates ◽

Amphibian Skin ◽

Amphibian Species ◽

Wide Range ◽

Skin Morphology ◽

And Function

Amphibian skin is highly variable in structure and function across anurans, and plays an important role in physiological homeostasis and immune defence. For example, skin sloughing has been shown to reduce pathogen loads on the skin, such as the lethal fungus Batrachochytrium dendrobatidis ( Bd ), but interspecific variation in sloughing frequency is largely unknown. Using phylogenetic linear mixed models, we assessed the relationship between skin turnover rate, skin morphology, ecological traits and overall evidence of Bd -driven declines. We examined skin sloughing rates in 21 frog species from three continents, as well as structural skin characteristics measured from preserved specimens. We found that sloughing rate varies significantly with phylogenetic group, but was not associated with evidence of Bd -driven declines, or other skin characteristics examined. This is the first comparison of sloughing rate across a wide range of amphibian species, and creates the first database of amphibian sloughing behaviour. Given the strong phylogenetic signal observed in sloughing rate, approximate sloughing rates of related species may be predicted based on phylogenetic position. While not related to available evidence of declines, understanding variation in sloughing rate may help explain differences in the severity of infection in genera with relatively slow skin turnover rates (e.g. Atelopus ).

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ITS1 Copy Number Varies among Batrachochytrium dendrobatidis Strains: Implications for qPCR Estimates of Infection Intensity from Field-Collected Amphibian Skin Swabs

PLoS ONE ◽

10.1371/journal.pone.0059499 ◽

2013 ◽

Vol 8 (3) ◽

pp. e59499 ◽

Cited By ~ 56

Author(s):

Ana V. Longo ◽

David Rodriguez ◽

Domingos da Silva Leite ◽

Luís Felipe Toledo ◽

Cinthya Mendoza Almeralla ◽

...

Keyword(s):

Copy Number ◽

Batrachochytrium Dendrobatidis ◽

Infection Intensity ◽

Amphibian Skin

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

Applied and Environmental Microbiology ◽

10.1128/aem.00186-17 ◽

2017 ◽

Vol 83 (9) ◽

Cited By ~ 12

Author(s):

Carly R. Muletz-Wolz ◽

Graziella V. DiRenzo ◽

Stephanie A. Yarwood ◽

Evan H. Campbell Grant ◽

Robert C. Fleischer ◽

...

Keyword(s):

Fungal Pathogen ◽

Batrachochytrium Dendrobatidis ◽

Bacterial Species ◽

Rrna Gene ◽

Amphibian Skin ◽

Amphibian Species ◽

Protective Function ◽

Content Type ◽

Skin Bacteria ◽

Salamander Species

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

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Amphibian skin defences show variation in ability to inhibit growth of Batrachochytrium dendrobatidis isolates from the Global Panzootic Lineage

Microbiology ◽

10.1099/mic.0.000570 ◽

2017 ◽

Vol 163 (12) ◽

pp. 1835-1838 ◽

Cited By ~ 5

Author(s):

Rachael Ellen Antwis ◽

Ché Weldon

Keyword(s):

Batrachochytrium Dendrobatidis ◽

Amphibian Skin

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Invasive vegetation affects amphibian skin microbiota and body condition

PeerJ ◽

10.7717/peerj.8549 ◽

2020 ◽

Vol 8 ◽

pp. e8549 ◽

Cited By ~ 2

Author(s):

Obed Hernández-Gómez ◽

Allison Q. Byrne ◽

Alex R. Gunderson ◽

Thomas S. Jenkinson ◽

Clay F. Noss ◽

...

Keyword(s):

Microbial Communities ◽

Body Condition ◽

Invasive Plant ◽

Batrachochytrium Dendrobatidis ◽

Community Diversity ◽

Habitat Modification ◽

Sequence Variant ◽

Soil Arthropods ◽

Amphibian Skin ◽

Skin Microbiota

Invasive plants are major drivers of habitat modification and the scale of their impact is increasing globally as anthropogenic activities facilitate their spread. In California, an invasive plant genus of great concern is Eucalyptus. Eucalyptus leaves can alter soil chemistry and negatively affect underground macro- and microbial communities. Amphibians serve as excellent models to evaluate the effect of Eucalyptus invasion on ground-dwelling species as they predate on soil arthropods and incorporate soil microbes into their microbiotas. The skin microbiota is particularly important to amphibian health, suggesting that invasive plant species could ultimately affect amphibian populations. To investigate the potential for invasive vegetation to induce changes in microbial communities, we sampled microbial communities in the soil and on the skin of local amphibians. Specifically, we compared Batrachoseps attenuatus skin microbiomes in both Eucalyptus globulus (Myrtaceae) and native Quercusagrifolia (Fagaceae) dominated forests in the San Francisco Bay Area. We determined whether changes in microbial diversity and composition in both soil and Batrachoseps attenuatus skin were associated with dominant vegetation type. To evaluate animal health across vegetation types, we compared Batrachoseps attenuatus body condition and the presence/absence of the amphibian skin pathogen Batrachochytrium dendrobatidis. We found that Eucalyptus invasion had no measurable effect on soil microbial community diversity and a relatively small effect (compared to the effect of site identity) on community structure in the microhabitats sampled. In contrast, our results show that Batrachoseps attenuatus skin microbiota diversity was greater in Quercus dominated habitats. One amplicon sequence variant identified in the family Chlamydiaceae was observed in higher relative abundance among salamanders sampled in Eucalyptus dominated habitats. We also observed that Batrachoseps attenuatus body condition was higher in Quercus dominated habitats. Incidence of Batrachochytrium dendrobatidis across all individuals was very low (only one Batrachochytrium dendrobatidis positive individual). The effect on body condition demonstrates that although Eucalyptus may not always decrease amphibian abundance or diversity, it can potentially have cryptic negative effects. Our findings prompt further work to determine the mechanisms that lead to changes in the health and microbiome of native species post-plant invasion.

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Bioclimatic and anthropogenic variables shape the occurrence of Batrachochytrium dendrobatidis over a large latitudinal gradient

Scientific Reports ◽

10.1038/s41598-021-96535-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Mario Alvarado-Rybak ◽

Manuel Lepe-Lopez ◽

Alexandra Peñafiel-Ricaurte ◽

Andrés Valenzuela-Sánchez ◽

Catalina Valdivia ◽

...

Keyword(s):

Latitudinal Gradient ◽

Batrachochytrium Dendrobatidis ◽

Biodiversity Loss ◽

Quantitative Real Time Pcr ◽

Amphibian Skin ◽

Amphibian Species ◽

Risk Areas ◽

Host Ecology ◽

New Evidence ◽

Central South

AbstractAmphibian chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), has caused the greatest known loss of biodiversity due to an infectious disease. We used Bd infection data from quantitative real-time PCR (qPCR) assays of amphibian skin swabs collected across Chile during 2008–2018 to model Bd occurrence with the aim to determine bioclimatic and anthropogenic variables associated with Bd infection. Also, we used Bd presence/absence records to identify geographical Bd high-risk areas and compare Bd prevalence and infection loads between amphibian families, ecoregions, and host ecology. Data comprised 4155 Bd-specific qPCR assays from 162 locations across a latitudinal gradient of 3700 km (18º to 51ºS). Results showed a significant clustering of Bd associated with urban centres and anthropogenically highly disturbed ecosystems in central-south Chile. Both Bd prevalence and Bd infection loads were higher in aquatic than terrestrial amphibian species. Our model indicated positive associations of Bd prevalence with altitude, temperature, precipitation and human-modified landscapes. Also, we found that macroscale drivers, such as land use change and climate, shape the occurrence of Bd at the landscape level. Our study provides with new evidence that can improve the effectiveness of strategies to mitigate biodiversity loss due to amphibian chytridiomycosis.

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Most of the Dominant Members of Amphibian Skin Bacterial Communities Can Be Readily Cultured

Applied and Environmental Microbiology ◽

10.1128/aem.01486-15 ◽

2015 ◽

Vol 81 (19) ◽

pp. 6589-6600 ◽

Cited By ~ 25

Author(s):

Jenifer B. Walke ◽

Matthew H. Becker ◽

Myra C. Hughey ◽

Meredith C. Swartwout ◽

Roderick V. Jensen ◽

...

Keyword(s):

Bacterial Community ◽

Batrachochytrium Dendrobatidis ◽

Amplicon Sequencing ◽

Reference Database ◽

Rrna Gene ◽

Amphibian Skin ◽

Amphibian Species ◽

Content Type ◽

Average Percentage ◽

Culture Independent

ABSTRACTCurrently, it is estimated that only 0.001% to 15% of bacteria in any given system can be cultured by use of commonly used techniques and media, yet culturing is critically important for investigations of bacterial function. Despite this situation, few studies have attempted to link culture-dependent and culture-independent data for a single system to better understand which members of the microbial community are readily cultured. In amphibians, some cutaneous bacterial symbionts can inhibit establishment and growth of the fungal pathogenBatrachochytrium dendrobatidis, and thus there is great interest in using these symbionts as probiotics for the conservation of amphibians threatened byB. dendrobatidis. The present study examined the portion of the culture-independent bacterial community (based on Illumina amplicon sequencing of the 16S rRNA gene) that was cultured with R2A low-nutrient agar and whether the cultured bacteria represented rare or dominant members of the community in the following four amphibian species: bullfrogs (Lithobates catesbeianus), eastern newts (Notophthalmus viridescens), spring peepers (Pseudacris crucifer), and American toads (Anaxyrus americanus). To determine which percentage of the community was cultured, we clustered Illumina sequences at 97% similarity, using the culture sequences as a reference database. For each amphibian species, we cultured, on average, 0.59% to 1.12% of each individual's bacterial community. However, the average percentage of bacteria that were culturable for each amphibian species was higher, with averages ranging from 2.81% to 7.47%. Furthermore, most of the dominant operational taxonomic units (OTUs), families, and phyla were represented in our cultures. These results open up new research avenues for understanding the functional roles of these dominant bacteria in host health.

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Germ Tube Mediated Invasion of Batrachochytrium dendrobatidis in Amphibian Skin Is Host Dependent

PLoS ONE ◽

10.1371/journal.pone.0041481 ◽

2012 ◽

Vol 7 (7) ◽

pp. e41481 ◽

Cited By ~ 41

Author(s):

Pascale Van Rooij ◽

An Martel ◽

Katharina D'Herde ◽

Melanie Brutyn ◽

Siska Croubels ◽

...

Keyword(s):

Germ Tube ◽

Batrachochytrium Dendrobatidis ◽

Amphibian Skin

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The Fungicide Chlorothalonil Changes the Amphibian Skin Microbiome: A Potential Factor Disrupting a Host Disease-Protective Trait

Applied Microbiology ◽

10.3390/applmicrobiol1010004 ◽

2021 ◽

Vol 1 (1) ◽

pp. 26-37

Author(s):

Randall R. Jiménez ◽

Gilbert Alvarado ◽

Clemens Ruepert ◽

Erick Ballestero ◽

Simone Sommer

Keyword(s):

Batrachochytrium Dendrobatidis ◽

Bacterial Community Composition ◽

Model Organism ◽

Amplicon Sequencing ◽

Anthropogenic Factors ◽

Skin Microbiome ◽

Amphibian Skin ◽

16S Rrna Amplicon Sequencing ◽

Potential Factor ◽

Inhibitory Bacteria

The skin microbiome is an important part of amphibian immune defenses and protects against pathogens such as the chytrid fungus Batrachochytrium dendrobatidis (Bd), which causes the skin disease chytridiomycosis. Alteration of the microbiome by anthropogenic factors, like pesticides, can impact this protective trait, disrupting its functionality. Chlorothalonil is a widely used fungicide that has been recognized as having an impact on amphibians, but so far, no studies have investigated its effects on amphibian microbial communities. In the present study, we used the amphibian Lithobates vibicarius from the montane forest of Costa Rica, which now appears to persist despite ongoing Bd-exposure, as an experimental model organism. We used 16S rRNA amplicon sequencing to investigate the effect of chlorothalonil on tadpoles’ skin microbiome. We found that exposure to chlorothalonil changes bacterial community composition, with more significant changes at a higher concentration. We also found that a larger number of bacteria were reduced on tadpoles’ skin when exposed to the higher concentration of chlorothalonil. We detected four presumed Bd-inhibitory bacteria being suppressed on tadpoles exposed to the fungicide. Our results suggest that exposure to a widely used fungicide could be impacting host-associated bacterial communities, potentially disrupting an amphibian protective trait against pathogens.

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