Abstract
In the Neotropics, almost every species of the stream-dwelling harlequin toads (genus Atelopus) have experienced catastrophic declines. The persistence of lowland species of Atelopus could be explained by the lower growth rate of Batrachochytrium dendrobatidis (Bd) at temperatures above 25°C. We tested the complementary hypothesis that the toads' skin bacterial microbiota acts as a protective barrier against the pathogen, perhaps delaying or impeding the symptomatic phase of chytridiomycosis. We isolated 148 cultivable bacterial strains from three lowland Atelopus species and quantified the anti-Bd activity through antagonism assays. Twenty-six percent (38 strains representing 12 species) of the bacteria inhibited Bd growth and just two of them were shared among the toad species sampled in different localities. Interestingly, the strongest anti-Bd activity was measured in bacteria isolated from A. elegans, the only species that tested positive for the pathogen. The cutaneous bacterial microbiota is thus likely a fitness-enhancing trait that may (adaptation) or not (exaptation) have appeared because of natural selection mediated by chytridiomycosis. Our findings reveal bacterial strains for development of local probiotic treatments against chytridiomycosis and also shed light on the mechanisms behind the frog-bacteria-pathogen interaction.
Highlights
The world’s amphibians are facing a conservation crisis due to a variety of factors [1], with the newest and perhaps most insidious threat coming from an emerging global pathogen, the microscopic fungus Batrachochytrium dendrobatidis, or Bd [2]
Among all three hosts we identified 12 bacterial species with anti-Bd activity belonging to six genera: Pseudomonas, Acinetobacter, Stenotrophomonas, Comamonas, Chryseobacterium and Elizabethkingia (Table 1)
Our results demonstrated that 12 bacterial species isolated from three Atelopus species from the Colombian lowlands inhibit Bd growth
Summary
The world’s amphibians are facing a conservation crisis due to a variety of factors [1], with the newest and perhaps most insidious threat coming from an emerging global pathogen, the microscopic fungus Batrachochytrium dendrobatidis, or Bd [2]. This fungus is the etiological agent of chytridiomycosis, and has been implicated in many enigmatic declines worldwide [3,4,5]. Individuals, populations and species of amphibians are known to vary in their susceptibility to chytridiomycosis, but the causes of this variation are not well understood [16]. Variation in the cutaneous microbial community of amphibian skin may be a key factor in resistance to chytridiomycosis [26,28,29,30]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
