Skin bacterial diversity of Panamanian frogs is associated with host susceptibility and presence of Batrachochytrium dendrobatidis

Abstract

Symbiotic bacteria on amphibian skin can inhibit growth of the fungus Batrachochytrium dendrobatidis (Bd) that has caused dramatic population declines and extinctions of amphibians in the Neotropics. It remains unclear how the amphibians' skin microbiota is influenced by environmental bacterial reservoirs, host-associated factors such as susceptibility to pathogens, and pathogen presence in tropical amphibians. We sampled skin bacteria from five co-occurring frog species that differ in Bd susceptibility at one Bd-naive site, and sampled one of the non-susceptible species from Bd-endemic and Bd-naive sites in Panama. We hypothesized that skin bacterial communities (1) would be distinct from the surrounding environment regardless of the host habitat, (2) would differ between Bd susceptible and non-susceptible species and (3) would differ on hosts in Bd-naive and Bd-endemic sites. We found that skin bacterial communities were enriched in bacterial taxa that had low relative abundances in the environment. Non-susceptible species had very similar skin bacterial communities that were enriched in particular taxa such as the genera Pseudomonas and Acinetobacter. Bacterial communities of Craugastor fitzingeri in Bd-endemic sites were less diverse than in the naive site, and differences in community structure across sites were explained by changes in relative abundance of specific bacterial taxa. Our results indicate that skin microbial structure was associated with host susceptibility to Bd and might be associated to the history of Bd presence at different sites.

Environmental fluctuations and host skin bacteria shift survival advantage between frogs and their fungal pathogen

“…One such example is A. rhizosphaerae, an OTU that was suppressed during the cool-dry season in our experiment (Figure 8). Non-susceptible species have bacterial communities enriched with Acinetobacter (Rebollar et al, 2016). Over the last few years, researchers have tested 27 isolates of A. rhizosphaerae against Bd, yet only 60% of them were able to inhibit the pathogen (Woodhams et al, 2015).…”

Short-Term Exposure to Coal Combustion Waste Has Little Impact on the Skin Microbiome of Adult Spring Peepers (Pseudacris crucifer)

“…Next, unique compounds that were only detected in a single sample were disregarded as noise. Finally, all features that had a peak area of less than 3,000 milli-absorbance units (mAU) were disregarded as minor components (32).…”

Direct and Indirect Horizontal Transmission of the Antifungal Probiotic Bacterium Janthinobacterium lividum on Green Frog (Lithobates clamitans) Tadpoles

“…In this study, we identified 5,981 bacterial OTUs on L. clamitans skin, and these communities were dominated by two Pseudomonas OTUs. Several members of the genus Pseudomonas are known to produce antifungal and antibiotic compounds, and their dominance on the amphibian skin may indicate a defensive function (14,31,45,69,71). A recent study on Bufo boreas boreas tadpoles that compared bacterial taxa with a B. dendrobatidis-inhibitory bacterial OTU database found that tadpoles hosted significantly more inhibitory OTUs than other life stages or environmental samples (46).…”

“…In this study, we tracked the presence and abundance of the probiotic bacterium J. lividum through time using two different techniques: bacterial culturing using selective media for rifampin-resistant strains (33) and 16S amplicon sequencing, which is a culture-independent technique increasingly used to describe the bacterial community structure in amphibians (14,45,58,68,69). Despite the great advantages of using 16S amplicon sequencing for community profiling, one caveat is that this method does not distinguish between the natural J. lividum and the rifampin-resistant inoculated strain.…”