Bacterial-Fungal Interactions Affect the Physiology of the Causative Agent of White-Nose Syndrome, Pseudogymnoascus destructans

Abstract

The pathogenic fungus Pseudogymnoascus destructans causes white-nose syndrome of bats and has led to massive population declines in North American bat species. Infection with Pseudogymnoascus destructans is partially dependent on host-microbiome-pathogen interactions on the bat’s skin. Bacterial-fungal interactions range from mutualistic to antagonistic in nature and exist in a range of environments and hosts. One of the most specific bacterial-fungal interactions occurs when fungi harbor an endohyphal bacterium. The objective of this project was to characterize a bacterial-fungal interaction between P. destructans and Nocardia sp. using molecular, physiological, and microscopic techniques. I found molecular and visual evidence of an endohyphal bacterium in the genus Nocardia in 18 isolates of P. destructans. Fungal isolates were subjected to antibiotic treatment to remove the bacterial associate. Isolates that were released of their relationship with Nocardia had higher protease activity and were shown to have increased expression of the gene encoding virulence factor SP1. This work demonstrates the first endohyphal bacterial-fungal interaction in a wildlife pathogen and a likely antagonistic relationship between the bacterium and fungus.