Bacterial flora on Cascades frogs in the Klamath mountains of California

Roth, Tara; Foley, Janet E.; Worth, Joy; Piovia‐Scott, Jonah; Pope, Karen L.; Lawler, Sharon P.

doi:10.1016/j.cimid.2013.07.002

Cited by 20 publications

(18 citation statements)

References 56 publications

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“…Pseudomonas is a large, ecologically diverse group, and members of this genus include known pathogens, common environmental bacteria, and commensals, which have been found on the skin of amphibians in previous studies (39), sometimes at very high relative abundances comparable with the relative abundances observed in the current study (58). Pseudomonas species are commonly used in biological control in agriculture (4) and have been shown to have anti-Bd activity in laboratory tests (59), although isolates from Rana cascadae, a close relative of R. sierrae, showed no anti-Bd activity (58). Our finding that the abundance of Pseudomonas species declined sharply with Bd infection suggests that in the R. sierrae system, the sensitivity of Pseudomonas species to disturbance by Bd may render these bacteria ineffective at providing protection against Bd infection, regardless of whether they produce anti-Bd metabolites.…”

Section: Coordinated Laboratory and Field Studies Show Bd Infection Dsupporting

confidence: 63%

“…In general, it will be important to determine if the disturbance effect of Bd on the R. sierrae microbiome that we observed is generally true for other amphibian species. Roth et al (58) tested for differences in cultured bacterial isolates between infected and uninfected R. cascadae and found no effect, although differences between the findings of Roth et al (58) and the current study may be affected by methods (culture-based vs. pyrosequencing) or, potentially, differences in severity of infection. [Roth et al (58) report binary Bd infection rather than Bd load, but another study found relatively low loads in R. cascadae (66), compared with the Bd loads observed in R. sierrae in the current study.…”

Section: Coordinated Laboratory and Field Studies Show Bd Infection Dmentioning

confidence: 75%

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The pathogenBatrachochytrium dendrobatidisdisturbs the frog skin microbiome during a natural epidemic and experimental infection

Jani¹,

Briggs

2014

Proc. Natl. Acad. Sci. U.S.A.

227

294

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Significance Animals are inhabited by communities of microbes (the microbiome) that potentially interact with pathogens. Detailed studies of microbiome–pathogen interactions in nature are rare, and even when correlations are observed, determining causal relationships is challenging. The microbiome–pathogen relationship is of particular interest in the case of Batrachochytrium dendrobatidis , a chytrid fungus that infects the skin of amphibians and is causing amphibian declines worldwide. We documented a strong correlation between pathogen load and skin bacterial communities of frogs during natural disease episodes. We then showed experimentally that infection alters the microbiome, with similar bacteria responding in both laboratory and field. The results indicate that the chytrid pathogen drives changes in the amphibian skin microbiome during disease episodes in wild frogs.

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Section: Coordinated Laboratory and Field Studies Show Bd Infection Dsupporting

confidence: 63%

Section: Coordinated Laboratory and Field Studies Show Bd Infection Dmentioning

confidence: 75%

The pathogenBatrachochytrium dendrobatidisdisturbs the frog skin microbiome during a natural epidemic and experimental infection

Jani¹,

Briggs

2014

Proc. Natl. Acad. Sci. U.S.A.

227

294

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“…R2A is a low-nutrient medium originally designed for cultivation of bacteria from potable water (57). It was chosen because it is the most commonly used medium for culturing amphibian-associated bacteria (25,41,42,45,(58)(59)(60)(61) and because it supports the growth of slow-growing bacteria, which would quickly be suppressed by faster-growing species on a high-nutrient medium. The culture-dependent swabs obtained from bullfrogs and newts were plated directly onto R2A plates in the field by streaking each swab in a "W" pattern while simultaneously rotating the swab.…”

Section: Methodsmentioning

confidence: 99%

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

Walke

Becker

Hughey

et al. 2015

Appl Environ Microbiol

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Currently, 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 pathogen Batrachochytrium dendrobatidis, and thus there is great interest in using these symbionts as probiotics for the conservation of amphibians threatened by B. 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. Microorganisms represent a large portion of global biodiversity and are responsible for many important ecological functions, yet the majority of microbes have not been cultured (1-3). It is estimated that only 0.001% to 15% of microbes can be cultured by use of commonly used techniques and media (2, 4), although some recent attempts at culturing the uncultured have been successful. For example, a prevalent and abundant human gut bacterium with potential biomedical importance was recently cultured by a gene-targeted approach (5). Still, only a third of known bacterial phyla have cultured representatives (6). Recent advances in culture-independent rRNA-based molecular approaches have allowed for a greater understanding of bacterial diversity (1,7,8), but in most cases, the only data we have about uncultured microbes are the DNA sequences obtained directly from the environment. Next-generation sequencing in some cases has led to the discovery of entire groups, such as the TM7 candidate division, often found in terrestrial, aquatic, and clinical habitats (9). This group is phylogenetically distinct and widespread yet has not been isolated in pure culture (9-12). There are also bacteri...

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“…Symbiotic skin bacteria have been identified as a potential defense against B. dendrobatidis in several species via the production and constitutive secretion of metabolites that inhibit in vitro growth of the fungus (43)(44)(45)(46). The interactions of these bacteria with their host must be considered when antimicrobial agents are applied to the skin.…”

mentioning

confidence: 99%

Evaluation of Amphotericin B and Chloramphenicol as Alternative Drugs for Treatment of Chytridiomycosis and Their Impacts on Innate Skin Defenses

Holden

Ebert

Canning

et al. 2014

Appl Environ Microbiol

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c Chytridiomycosis, an amphibian skin disease caused by the emerging fungal pathogen Batrachochytrium dendrobatidis, has been implicated in catastrophic global amphibian declines. The result is an alarming decrease in amphibian diversity that is a great concern for the scientific community. Clinical trials testing potential antifungal drugs are needed to identify alternative treatments for amphibians infected with this pathogen. In this study, we quantified the MICs of chloramphenicol (800 g/ml), amphotericin B (0.8 to 1.6 g/ml), and itraconazole (Sporanox) (20 ng/ml) against B. dendrobatidis. Both chloramphenicol and amphotericin B significantly reduced B. dendrobatidis infection in naturally infected southern leopard frogs (Rana [Lithobates] sphenocephala), although neither drug was capable of complete fungal clearance. Long-term exposure of R. sphenocephala to these drugs did not inhibit antimicrobial peptide (AMP) synthesis, indicating that neither drug is detrimental to this important innate skin defense. However, we observed that chloramphenicol, but not amphotericin B or itraconazole, inhibited the growth of multiple R. sphenocephala skin bacterial isolates in vitro at concentrations below the MIC against B. dendrobatidis. These results indicate that treatment with chloramphenicol might dramatically alter the protective natural skin microbiome when used as an antifungal agent. This study represents the first examination of the effects of alternative antifungal drug treatments on amphibian innate skin defenses, a crucial step to validating these treatments for practical applications.

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Bacterial flora on Cascades frogs in the Klamath mountains of California

Cited by 20 publications

References 56 publications

The pathogenBatrachochytrium dendrobatidisdisturbs the frog skin microbiome during a natural epidemic and experimental infection

The pathogenBatrachochytrium dendrobatidisdisturbs the frog skin microbiome during a natural epidemic and experimental infection

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

Evaluation of Amphotericin B and Chloramphenicol as Alternative Drugs for Treatment of Chytridiomycosis and Their Impacts on Innate Skin Defenses

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