Greater Species Richness of Bacterial Skin Symbionts Better Suppresses the Amphibian Fungal Pathogen Batrachochytrium Dendrobatidis


The symbiotic microbes that grow in and on many organisms can play important roles in protecting their hosts from pathogen infection. While species diversity has been shown to influence community function in many other natural systems, the question of how species diversity of host-associated symbiotic microbes contributes to pathogen resistance is just beginning to be explored. Understanding diversity effects on pathogen resistance could be particularly helpful in combating the fungal pathogen Batrachochytrium dendrobatidis (Bd) which has caused dramatic population declines in many amphibian species and is a major concern for amphibian conservation. Our study investigates the ability of host-associated bacteria to inhibit the proliferation of Bd when grown in experimentally assembled biofilm communities that differ in species number and composition. Six bacterial species isolated from the skin of Cascades frogs (Rana cascadae) were used to assemble bacterial biofilm communities containing 1, 2, 3, or all 6 bacterial species. Biofilm communities were grown with Bd for 7 days following inoculation. More speciose bacterial communities reduced Bd abundance more effectively. This relationship between bacterial species richness and Bd suppression appeared to be driven by dominance effects—the bacterial species that were most effective at inhibiting Bd dominated multi-species communities—and complementarity: multi-species communities inhibited Bd growth more than monocultures of constituent species. These results underscore the notion that pathogen resistance is an emergent property of microbial communities, a consideration that should be taken into account when designing probiotic treatments to reduce the impacts of infectious disease.

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This research was supported by grants from the US Fish and Wildlife Service to JPS, SPL, and JEF, the University of California, Davis Academic Senate to SPL and JEF. A portion of the DNA sequencing work was supported by an NSF grant (DEB: 1146284) awarded to VJM. Valuable assistance was provided by Tara Roth; statistical advice was provided by Jarrett Byrnes, Kyle Edwards, and Rebecca Best.

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Correspondence to Jonah Piovia-Scott.

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Piovia-Scott, J., Rejmanek, D., Woodhams, D.C. et al. Greater Species Richness of Bacterial Skin Symbionts Better Suppresses the Amphibian Fungal Pathogen Batrachochytrium Dendrobatidis . Microb Ecol 74, 217–226 (2017).

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  • Biofilm
  • Community function
  • Pathogen resistance
  • Microbial symbiont
  • Synergy