scholarly journals The Bacterially Produced Metabolite Violacein Is Associated with Survival of Amphibians Infected with a Lethal Fungus

2009 ◽  
Vol 75 (21) ◽  
pp. 6635-6638 ◽  
Author(s):  
Matthew H. Becker ◽  
Robert M. Brucker ◽  
Christian R. Schwantes ◽  
Reid N. Harris ◽  
Kevin P. C. Minbiole
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Plethodon Cinereus ◽  
Chytrid Fungus ◽  
Experimental Exposure ◽  
Amphibian Species ◽  
Mortality And Morbidity ◽  
Antifungal Metabolite ◽  
Microbial Species ◽  
Skin Bacteria ◽  
Janthinobacterium Lividum

ABSTRACT The disease chytridiomycosis, which is caused by the chytrid fungus Batrachochytrium dendrobatidis, is associated with recent declines in amphibian populations. Susceptibility to this disease varies among amphibian populations and species, and resistance appears to be attributable in part to the presence of antifungal microbial species associated with the skin of amphibians. The betaproteobacterium Janthinobacterium lividum has been isolated from the skins of several amphibian species and produces the antifungal metabolite violacein, which inhibits B. dendrobatidis. In this study, we added J. lividum to red-backed salamanders (Plethodon cinereus) to obtain an increased range of violacein concentrations on the skin. Adding J. lividum to the skin of the salamander increased the concentration of violacein on the skin, which was strongly associated with survival after experimental exposure to B. dendrobatidis. As expected from previous work, some individuals that did not receive J. lividum and were exposed to B. dendrobatidis survived. These individuals had concentrations of bacterially produced violacein on their skins that were predicted to kill B. dendrobatidis. Our study suggests that a threshold violacein concentration of about 18 μM on a salamander's skin prevents mortality and morbidity caused by B. dendrobatidis. In addition, we show that over one-half of individuals in nature support antifungal bacteria that produce violacein, which suggests that there is a mutualism between violacein-producing bacteria and P. cinereus and that adding J. lividum is effective for protecting individuals that lack violacein-producing skin bacteria.

scholarly journals Establishement of a national monitoring program based on environmental DNA for amphibians and the chytrid fungus Batrachochytrium dendrobatidis     

2021 ◽  
Vol 4 ◽  
Author(s):  
Omneya Osman ◽  
Johan Andersson ◽  
Tomas Larsson ◽  
Mats Töpel ◽  
Alexander Eiler
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
National Level ◽  
Monitoring Program ◽  
12S Rrna ◽  
Rrna Gene ◽  
Chytrid Fungus ◽  
Rana Arvalis ◽  
Amphibian Species ◽  
National Monitoring ◽  
Wide Range

National monitoring programs provide the basis for evaluating the integrity of ecosystems, their responses to disturbances, and the success of actions taken to conserve or recover biodiversity. In this study, we successfully established a national program for the invasive chytrid fungus Batrachochytrium dendrobatidis (Bd) based on dual TaqMan assays. Amphibian diversity based on metabarcoding of the mitochondrial 12S rRNA gene was also performed. Assays were optimized for sensitive detection of target species from a wide range of amphibian ponds with variable potential of inhibitions for eDNA based detection. An amphibian mock community of 5 species was used to validate the metabarcoding approach while internal standards were used in the case of the dual TaqMan assays. First sampling of over 170 ponds in Norway resulted in Bd detection in 12 environmental samples and one swab sample taken over multiple years indicating the establishment of Bd in Norway. Five amphibian species Bufo bufo, Lissotriton vulgaris, Triturus cristatus, Rana arvalis and Rana temporaria as predicted from data in long-term citizen science reporting systems were widely detected in the collected eDNA samples. Our large scale-monitoring program indicates a low risk of a Bd outbreak and amphibian decline caused by chytridiomycosis but continued monitoring is recommended in the future. These findings indicate that eDNA is an effective method to detect invasive species, and to monitor endangered amphibian species. Still, several shortcomings (such as PCR inhibitors and sample volume) were identified that need to be addressed to improve eDNA-based monitoring at the national level.

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

2017 ◽  
Vol 83 (9) ◽  
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.

scholarly journals Composition of symbiotic bacteria predicts survival in Panamanian golden frogs infected with a lethal fungus

2015 ◽  
Vol 282 (1805) ◽  
pp. 20142881 ◽  
Author(s):  
Matthew H. Becker ◽  
Jenifer B. Walke ◽  
Shawna Cikanek ◽  
Anna E. Savage ◽  
Nichole Mattheus ◽  
...  
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Population Declines ◽  
Amphibian Species ◽  
Amphibian Population ◽  
New Approach ◽  
Skin Bacteria ◽  
Probiotic Treatment ◽  
Host Health ◽  
The Face ◽  
Inhibitory Bacteria

Symbiotic microbes can dramatically impact host health and fitness, and recent research in a diversity of systems suggests that different symbiont community structures may result in distinct outcomes for the host. In amphibians, some symbiotic skin bacteria produce metabolites that inhibit the growth of Batrachochytrium dendrobatidis (Bd), a cutaneous fungal pathogen that has caused many amphibian population declines and extinctions. Treatment with beneficial bacteria (probiotics) prevents Bd infection in some amphibian species and creates optimism for conservation of species that are highly susceptible to chytridiomycosis, the disease caused by Bd. In a laboratory experiment, we used Bd-inhibitory bacteria from Bd-tolerant Panamanian amphibians in a probiotic development trial with Panamanian golden frogs, Atelopus zeteki , a species currently surviving only in captive assurance colonies. Approximately 30% of infected golden frogs survived Bd exposure by either clearing infection or maintaining low Bd loads, but this was not associated with probiotic treatment. Survival was instead related to initial composition of the skin bacterial community and metabolites present on the skin. These results suggest a strong link between the structure of these symbiotic microbial communities and amphibian host health in the face of Bd exposure and also suggest a new approach for developing amphibian probiotics.

scholarly journals Mosquitoes as a potential vector for the transmission of the amphibian chytrid fungus

2019 ◽  
Vol 29 (1) ◽  
pp. 39-44 ◽  
Author(s):  
John Gould ◽  
Jose W. Valdez ◽  
Michelle P. Stockwell ◽  
Simon Clulow ◽  
Michael J. Mahony
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Agar Plate ◽  
Insect Host ◽  
Chytrid Fungus ◽  
Amphibian Species ◽  
Potential Vector ◽  
Amphibian Chytrid Fungus ◽  
And Control ◽  
Zoospore Suspension

The amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), is an infectious disease responsible for the worldwide decline of amphibian species. To mitigate these declines, it is necessary to identify the various vectors by which the fungus can be transmitted between individuals and populations. The objective of this study was to determine whether adult female mosquitoes can carry and transfer Bd fungal cells. Mosquitoes were exposed to netting soaked in a live Bd zoospore suspension to determine whether they are able to externally acquire the fungus. Another group was placed into containers with a sterile and Bd-inoculated agar plate to determine whether mosquitoes could transfer Bd between these surfaces. Bd DNA was found to be present on mosquito legs exposed to inoculated netting and agar plates suggesting that Bd can be transmitted by the mosquito over short distances. This is the first study to demonstrate that an insect host may be a mechanical vector of Bd and suggests that we should begin to consider the role of mosquitoes in the dissemination and control of the fungus.

scholarly journals Single infection with Batrachochytrium dendrobatidis or Ranavirus does not increase probability of co-infection in a montane community of amphibians

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jaime Bosch ◽  
Camino Monsalve-Carcaño ◽  
Stephen J. Price ◽  
Jon Bielby
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Disease Outbreaks ◽  
Single Infection ◽  
Chytrid Fungus ◽  
Population Declines ◽  
Emerging Pathogens ◽  
Amphibian Species ◽  
Management Interventions ◽  
Amphibian Chytrid Fungus ◽  
Common Situation

AbstractUnderstanding the occurrence and consequence of co-infections can be useful in designing disease management interventions. Amphibians are the most highly threatened vertebrates, and emerging pathogens are a serious threat to their conservation. The amphibian chytrid fungus and the viruses of the Ranavirus genus are already widely distributed, causing disease outbreaks and population declines worldwide. However, we lack information about the occurrence and consequences of coinfection with these pathogens across age-classes of amphibian hosts. Here, we analyze the occurrence of infection of the amphibian chytrid fungus and ranaviruses during one season in two susceptible amphibian species at two different locations at which outbreaks have occurred. We found that the co-occurrence of both pathogens in a particular host is not common except in highly susceptible life-stages, and that single infections are the most common situation. Moreover, we found that the occurrence of one pathogen in a particular host did not predict the occurrence of the other. We attribute these results to the niches in which both pathogens proliferate in amphibian hosts.

scholarly journals Inhibition of Batrachochytrium dendrobatidis Caused by Bacteria Isolated from the Skin of Boreal Toads, Anaxyrus (Bufo) boreas boreas, from Grand Teton National Park, Wyoming, USA

2014 ◽  
Vol 7 ◽  
pp. MBI.S13639 ◽  
Author(s):  
Shawna T. Park ◽  
Amanda M. Collingwood ◽  
Sophie St-Hilaire ◽  
Peter P. Sheridan
Keyword(s):  
National Park ◽  
Batrachochytrium Dendrobatidis ◽  
Chytrid Fungus ◽  
Bacterial Isolates ◽  
Skin Microbiota ◽  
Amphibian Species ◽  
Bufo Boreas ◽  
Grand Teton National Park ◽  
Boreal Toads

The chytrid fungus Batrachochytrium dendrobatidis is a significant cause of the worldwide decline in amphibian populations; however, various amphibian species are capable of coexisting with B. dendrobatidis. Among them are boreal toads ( Anaxyrus ( Bufo) boreas boreas) located in Grand Teton National Park (GTNP) in Wyoming, USA. The purpose of this study was to identify cultivable bacterial isolates from the skin microbiota of boreal toads from GTNP and determine if they were capable of inhibiting B. dendrobatidis in vitro, and therefore might be a factor in the toad's coexistence with this pathogen. Isolates from 6 of 21 genera tested were found to inhibit the growth of B. dendrobatidis. These bacteria represent diverse lineages such as the Gammaproteobacteria, the Betaproteobacteria, and the Bacteroidetes/Chlorobium groups. We propose that these bacteria compete via microbial antagonism with B. dendrobatidis.

scholarly journals Mosquitoes as a Potential Vector for the Transmission of the Amphibian Chytrid Fungus

2019 ◽  
Author(s):  
John Gould ◽  
Jose Valdez ◽  
Michelle Stockwell ◽  
Simon Clulow ◽  
Michael Mahony
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Agar Plate ◽  
Insect Host ◽  
Chytrid Fungus ◽  
Amphibian Species ◽  
Potential Vector ◽  
Amphibian Chytrid Fungus ◽  
And Control ◽  
Zoospore Suspension

The amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), is an infectious disease responsible for the worldwide decline of amphibian species. To mitigate these declines, it is necessary to identify the various vectors by which the fungus can be transmitted between individuals and populations. The objective of this study was to determine whether adult female mosquitoes can carry and transfer Bd fungal cells. Mosquitoes were exposed to net soaked in a live Bd zoospore suspension to determine whether they are able to externally acquire the fungus. Another group was placed into containers with a sterile and Bd-inoculated agar plate to determine whether mosquitoes could transfer Bd between these surfaces. Bd DNA was found to be present on mosquito legs exposed to inoculated netting and agar plates suggesting that Bd can be transmitted by the mosquito over short distances This is the first study to demonstrate that an insect host may be a mechanical vector of Bd and suggests that we should begin to consider the role of mosquitoes in the dissemination and control of the fungus.

scholarly journals Social Behavior, Community Composition, Pathogen Strain, and Host Symbionts Influence Fungal Disease Dynamics in Salamanders

2021 ◽  
Vol 8 ◽  
Author(s):  
Mae Cowgill ◽  
Andrew G. Zink ◽  
Wesley Sparagon ◽  
Tiffany A. Yap ◽  
Hasan Sulaeman ◽  
...  
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Linear Models ◽  
Abiotic Factors ◽  
Historical Context ◽  
Maximum Temperature ◽  
Disease Dynamics ◽  
Amphibian Species ◽  
Host Interactions ◽  
Pathogen Invasion ◽  
Skin Bacteria

The emerging fungal pathogen, Batrachochytrium dendrobatidis (Bd), which can cause a fatal disease called chytridiomycosis, is implicated in the collapse of hundreds of host amphibian species. We describe chytridiomycosis dynamics in two co-occurring terrestrial salamander species, the Santa Lucia Mountains slender salamander, Batrachoseps luciae, and the arboreal salamander, Aneides lugubris. We (1) conduct a retrospective Bd-infection survey of specimens collected over the last century, (2) estimate present-day Bd infections in wild populations, (3) use generalized linear models (GLM) to identify biotic and abiotic correlates of infection risk, (4) investigate susceptibility of hosts exposed to Bd in laboratory trials, and (5) examine the ability of host skin bacteria to inhibit Bd in culture. Our historical survey of 2,866 specimens revealed that for most of the early 20th century (~1920–1969), Bd was not detected in either species. By the 1990s the proportion of infected specimens was 29 and 17% (B. luciae and A. lugubris, respectively), and in the 2010s it was 10 and 17%. This was similar to the number of infected samples from contemporary populations (2014–2015) at 10 and 18%. We found that both hosts experience signs of chytridiomycosis and suffered high Bd-caused mortality (88 and 71% for B. luciae and A. lugubris, respectively). Our GLM revealed that Bd-infection probability was positively correlated with intraspecific group size and proximity to heterospecifics but not to abiotic factors such as precipitation, minimum temperature, maximum temperature, mean temperature, and elevation, or to the size of the hosts. Finally, we found that both host species contain symbiotic skin-bacteria that inhibit growth of Bd in laboratory trials. Our results provide new evidence consistent with other studies showing a relatively recent Bd invasion of amphibian host populations in western North America and suggest that the spread of the pathogen may be enabled both through conspecific and heterospecific host interactions. Our results suggest that wildlife disease studies should assess host-pathogen dynamics that consider the interactions and effects of multiple hosts, as well as the historical context of pathogen invasion, establishment, and epizootic to enzootic transitions to better understand and predict disease dynamics.

scholarly journals Host Species is Linked to Pathogen Genotype for the Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis)

2021 ◽  
Author(s):  
Allison Q Byrne ◽  
Anthony W Waddle ◽  
Veronica Saenz ◽  
Michel Ohmer ◽  
Jef R Jaeger ◽  
...  
Keyword(s):  
United States ◽  
Host Species ◽  
Batrachochytrium Dendrobatidis ◽  
The United States ◽  
Ancestral Population ◽  
Chytrid Fungus ◽  
Species Identity ◽  
Amphibian Species ◽  
Host Pathogen ◽  
Amphibian Chytrid Fungus

Host-pathogen specificity can arise from certain selective environments mediated by both the host and pathogen. Therefore, understanding the degree to which host species identity is correlated with pathogen genotype can help reveal historical host-pathogen dynamics. One animal disease of particular concern is chytridiomycosis, typically caused by the global panzootic lineage of the amphibian chytrid fungus ( Batrachochytrium dendrobatidis , Bd), termed the Bd-GPL. This pathogen lineage has caused devastating declines in amphibian communities around the world. However, the origin of Bd-GPL and the fine-scale transmission dynamics of this lineage have remained a mystery. This is especially the case in North America where Bd-GPL is widespread, but disease outbreaks occur sporadically. Herein, we use Bd genetic data collected throughout the United States from amphibian skin swab and cultured isolate samples to investigate Bd genetic patterns. We highlight two case studies in Pennsylvania and Nevada where Bd-GPL genotypes are strongly correlated with host species identity. Specifically, in some localities bullfrogs ( Rana catesbeiana ) are infected with Bd-GPL lineages that are distinct from those infecting other sympatric amphibian species. Overall, we reveal a previously unknown association of Bd genotype with host species and identify the eastern United States as a Bd diversity hotspot and potential ancestral population for Bd-GPL.

Genotyping and differential bacterial inhibition of Batrachochytrium dendrobatidis in threatened amphibians in Costa Rica

Microbiology ◽  
2021 ◽  
Author(s):  
Juan G. Abarca ◽  
Steven M. Whitfield ◽  
Ibrahim Zuniga-Chaves ◽  
Gilbert Alvarado ◽  
Jacob Kerby ◽  
...  
Keyword(s):  
Costa Rica ◽  
Inhibitory Activity ◽  
Batrachochytrium Dendrobatidis ◽  
Mitigation Strategies ◽  
Chytrid Fungus ◽  
Fungal Isolation ◽  
Content Type ◽  
Bacterial Inhibition ◽  
Link Type ◽  
Skin Bacteria

Amphibians have declined around the world in recent years, in parallel with the emergence of an epidermal disease called chytridiomycosis, caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd). This disease has been associated with mass mortality in amphibians worldwide, including in Costa Rica, and Bd is considered an important contributor to the disappearance of this group of vertebrates. While many species are susceptible to the disease, others show tolerance and manage to survive infection with the pathogen. We evaluated the pathogen Bd circulating in Costa Rica and the capacity of amphibian skin bacteria to inhibit the growth of the pathogen in vitro. We isolated and characterized – genetically and morphologically – several Bd isolates from areas with declining populations of amphibians. We determined that the circulating chytrid fungus in Costa Rica belongs to the virulent strain Bd-GPL-2, which has been related to massive amphibian deaths worldwide; however, the isolates obtained showed genetic and morphological variation. Furthermore, we isolated epidermal bacteria from 12 amphibian species of surviving populations, some in danger of extinction, and evaluated their inhibitory activity against the collection of chytrid isolates. Through bioassays we confirmed the presence of chytrid-inhibitory bacterial genera in Costa Rican amphibians. However, we observed that the inhibition varied between different isolates of the same bacterial genus, and each bacterial isolation inhibited fungal isolation differently. In total, 14 bacterial isolates belonging to the genera Stenotrophomonas , Streptomyces , Enterobacter , Pseudomonas and Klebsiella showed inhibitory activity against all Bd isolates. Given the observed variation both in the pathogen and in the bacterial inhibition capacity, it is highly relevant to include local isolates and to consider the origin of the microorganisms when performing in vivo infection tests aimed at developing and implementing mitigation strategies for chytridiomycosis.

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