White-nose syndrome restructures bat skin microbiomes

The skin microbiome is an essential line of host defense against pathogens, yet our understanding of microbial communities and how they change when hosts become infected is limited. We investigated skin microbial composition in three North American bat species (Myotis lucifugus, Eptesicus fuscus, and Perimyotis subflavus) that have been impacted by the infectious disease, white-nose syndrome, caused by an invasive fungal pathogen, Pseudogymnoascus destructans. We compared bacterial and fungal composition from 154 skin swab samples and 70 environmental samples using a targeted 16S rRNA and ITS amplicon approach. We found that for M. lucifugus, a species that experiences high mortality from white-nose syndrome, bacterial microbiome diversity was dramatically lower when P. destructans is present. Key bacterial families--including those potentially involved in pathogen defense--significantly differed in abundance in bats infected with P. destructans compared to uninfected bats. However, skin bacterial diversity was not lower in E. fuscus or P. subflavus when P. destructans was present, despite populations of the latter species declining sharply from white-nose syndrome. The fungal species present on bats substantially overlapped with the fungal taxa present in the environment at the site where the bat was sampled, but fungal community composition was unaffected by the presence of P. destructans for any of the three bat species. This species-specific alteration in bat skin bacterial microbiomes after pathogen invasion may suggest a mechanism for the severity of WNS in M. lucifugus, but not for other bat species impacted by white-nose syndrome.