White nose syndrome of bats: Lipid profiling and enzyme identification in a host/pathogen system

Pseudogymnoascus destructans is a fungus isolated from cave-dwelling bats that is the pathogen responsible for white-nose syndrome (WNS) and the associated mass mortality of North American cave bats. This study addresses isolation and identification of biomolecules that may function in host/pathogen interactions in WNS. Fungal skin infections requires fungal adherence and growth on the host organism integumentary matrix, which consists of hard cornified insoluble structural proteins coated with lipid residues from epidermal cells or sebaceous secretions. There is a knowledge gap on how molecules present on the bat integument are utilized as carbon or nitrogen sources by P. destructans. I conducted biochemical investigations into biomolecules present on bat integument and secreted enzymes of P. destructans. I hypothesize that lipids on bat integument are utilized carbon and energy sources allowing P. destructans to disseminate causing infection. Conversely, some byproducts from lipid metabolism may inhibit fungal growth. P. destructans increases in surface area on bat integument while releasing proteolytic enzymes causing wing necrosis. In this study, differences in lipid content among tissues of three bat species/tissues with different life histories were determined by GC/MS of lipid TMS esters. Differences in surface lipid content among wings from thirteen bat species with differing susceptibilities to WNS was determined by derivatizing lipids to FAMEs and analyzing by GC/MS. The fungistatic properties of saturated and unsaturated FFAs were assessed using solid media. Finally, I isolated and identified a dominant subtilisin-like serine protease from in vitro P. destructans cultures. This study provides the first detailed examination into bat wing sebum chemical composition, P. destructans extracellular enzymes that may be involved in infection, and establishes the basis for examining their function in vivo during the infection process.