Antifungal Potential of the Skin Microbiota of Hibernating Big Brown Bats (Eptesicus fuscus) Infected With the Causal Agent of White-Nose Syndrome

Abstract

Little is known about skin microbiota in the context of the disease white-nose syndrome (WNS), caused by the fungus <i>Pseudogymnoascus destructans</i> (<i>Pd</i>), that has caused enormous declines of hibernating North American bats over the past decade. Interestingly, some hibernating species, such as the big brown bat (<i>Eptesicus fuscus</i>), appear resistant to the disease and their skin microbiota could play a role. However, a comprehensive analysis of the skin microbiota of <i>E. fuscus</i> in the context of <i>Pd</i> has not been done. In January 2017, we captured hibernating <i>E. fuscus</i>, sampled their skin microbiota, and inoculated them with <i>Pd</i> or sham inoculum. We allowed the bats to hibernate in the lab under controlled conditions for 11 weeks and then sampled their skin microbiota to test the following hypotheses: (1) <i>Pd</i> infection would not disrupt the skin microbiota of <i>Pd</i>-resistant <i>E. fuscus</i>; and (2) microbial taxa with antifungal properties would be abundant both before and after inoculation with <i>Pd</i>. Using high-throughput 16S rRNA gene sequencing, we discovered that beta diversity of <i>Pd</i>-inoculated bats changed more over time than that of sham-inoculated bats. Still, the most abundant taxa in the community were stable throughout the experiment. Among the most abundant taxa, <i>Pseudomonas</i> and <i>Rhodococcus</i> are known for antifungal potential against <i>Pd</i> and other fungi. Thus, in contrast to hypothesis 1, <i>Pd</i> infection destabilized the skin microbiota but consistent with hypothesis 2, bacteria with known antifungal properties remained abundant and stable on the skin. This study is the first to provide a comprehensive survey of skin microbiota of <i>E. fuscus</i>, suggesting potential associations between the bat skin microbiota and resistance to the <i>Pd</i> infection and WNS. These results set the stage for future studies to characterize microbiota gene expression, better understand mechanisms of resistance to WNS, and help develop conservation strategies.