Significant declines in amphibian populations are linked to factors such as urbanization and chytridiomycosis, a skin disease caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd). However, the relationship between habitat conditions, such as the degree of urbanization and distance from a water body, and the species richness of mutualistic cutaneous bacteria on redback salamanders (Plethodon cinereus) that inhibit the growth of Bdremains poorly understood. Salamanders found in stream-side, mid-upland, and high-upland habitats within nine urban, suburban, and rural sites were swabbed for cutaneous bacteria, which were then isolated in a laboratory setting. Challenge assays were conducted to assess inhibitory abilities of the bacterial isolates, and DNA sequence analysis was performed to identify bacterial species.
Results/Conclusions
Forty-six bacterial isolates were identified to species. While one species, Salinicoccus roseus, exhibited promising inhibitory abilities in the laboratory setting of this study, results of previous studies suggest several other of the isolated and identified bacterial species may inhibit Bd on salamanders in situ. Taken together, these results suggest that the species richness of bacteria shown to inhibit Bd was greater in urban areas than in suburban and rural areas, suggesting that urbanization does not necessarily exacerbate an amphibian’s susceptibility to infection. The findings of this research may help develop methods to alleviate amphibian declines through the bio-augmentation of bacterial species that may inhibit the growth of Bd, thereby mitigating the impact of chytridiomycosis on declining amphibian species.