Discovery of anti-fungal compounds from the immunobiome of North American bat species threatened by fungal infection with Pseudogymnoascus destructans

Abstract

With the spread of bat White-nose Syndrome decimating regional bat populations, finding a safe antifungal agent able to combat the causative agent Pseudogymnoascus destructans is a necessity. Upsetting the already fragile microbial balance on the skin of bats with, or at risk of developing, White-nose Syndrome is ill-advised. To avoid this, microbes that already reside on the skin of bats and in their hibernacula have been screened for anti-fungal activity. Co-culturing cutaneous and environmental microbes against Pseudogymnoascus destructans and closely related species has yielded many potential candidates for antifungal bioactivity. The nature of the bioactivity was assessed by extracting the potentially antifungal compounds, screening them alone for bioactivity, and obtaining LC/MS profiles of all extracted compounds. While five prime candidates were screened for activity, it was found that four were only able to produce significant inhibition when cocultured, indicating that their bioactivity is a result of resource competition or induction of antifungal compounds under the stress of co-culture conditions. The final strain shows innate antifungal properties based on the treatment of the Pseudogymnoascus fungi with compounds produced by the pure isolate strain. It shows increased bioactivity against Pseudogymnoascus destructans, specifically. The extracted compounds have been found to be stable for at least four weeks in solution without degrading and were able to maintain bioactivity for 8 weeks.