Inhibition of Pseudogymnoascus destructans, the causative agent of white-nose syndrome, by environmental microorganisms

White-nose syndrome, a disease that affects hibernating bats, has caused mass mortality in many bat populations since it was first detected in North America in 2006. This disease has both ecological and economic impacts, since bats are relied upon by the agricultural sector for natural pest-control. White-nose syndrome is caused by the psychrophilic fungus Pseudogymnoascus destructans, which is believed to be an invasive species in North America. Although biological and chemical agents able to inhibit the growth of P. destructans have been found, none of these have been put into widespread use, so the search for inhibitory agents continues. Environmental microorganisms are a diverse source of antibiotics and antifungals; therefore, the goal of this project was to isolate bacteria and fungi from three unique environments and screen these microorganisms for inhibitory activity towards P. destructans. Infected plant (rotten leaves, bark, wood) and mushroom samples collected from the area around Bush Lake and Timber Lake, British Columbia were plated on Sabouraud dextrose agar plates and incubated at 25°C to promote microbial growth. Additionally, fungi were isolated from dwarf mistletoe plants and soil samples collected at a mushroom farm in Summerland, British Columbia. Morphologically distinct bacterial and fungal colonies were isolated in pure culture and screened for inhibitory activity towards P. destructans. Ninety-three bacterial isolates were pre-screened using a direct contact streak assay, with 30 exhibiting inhibitory activity towards P. destructans. These 30 bacterial isolates plus 77 fungal isolates were then grown in V8 broth and the broth supernatant was collected and filtered before being used in a Kirby-Bauer style agar diffusion assay. Thirteen bacteria and seven fungi exhibited inhibitory activity towards P. destructans in the agar diffusion assay. Further characterization of the positive candidates could lead to the production of a novel biological control agent that could be used for treatment and/or prevention of WNS.