Psychrophilic and Psychrotolerant Fungi on Bats and the Presence of Geomyces spp. on Bat Wings Prior to the Arrival of White Nose Syndrome

Abstract

Since 2006, Geomyces destructans, the causative agent of white nose syndrome (WNS), has killed over 5.7 million bats in North America. The current hypothesis suggests that this novel fungus is an invasive species from Europe, but little is known about the diversity within the genus Geomyces and its distribution on bats in the United States. We documented the psychrophilic and psychrotolerant fungal flora of hibernating bats prior to the arrival of WNS using culture-based techniques. A total of 149 cultures, which were obtained from 30 bats in five bat hibernacula located in four caves and one mine, were sequenced for the entire internal transcribed spacer (ITS) nuclear ribosomal DNA (nrDNA) region. Approximately 53 operational taxonomic units (OTUs) at 97% similarity were recovered from bat wings, with the community dominated by fungi within the genera Cladosporium, Fusarium, Geomyces, Mortierella, Penicillium, and Trichosporon. Eleven Geomyces isolates were obtained and placed in at least seven distinct Geomyces clades based on maximum-likelihood phylogenetic analyses. Temperature experiments revealed that all Geomyces strains isolated are psychrotolerant, unlike G. destructans, which is a true psychrophile. Our results confirm that a large diversity of fungi, including several Geomyces isolates, occurs on bats prior to the arrival of WNS. Most of these isolates were obtained from damaged wings. Additional studies need to be conducted to determine potential ecological roles of these abundant Geomyces strains isolated from bats.

Fungi on white-nose infected bats (Myotis spp.) in Eastern Canada show no decline in diversity associated with Pseudogymnoascus destructans (Ascomycota: Pseudeurotiaceae) presence

“…did not change with the introduction of Pd to New Brunswick hibernacula. Johnson et al (2013) found that Pd-negative bats (n = 25) sampled April-May in Illinois had a much greater diversity of fungi than Pd-positive bats (n = 5) sampled in June in Indiana. Although Johnson et al (2013) suggested that it was presence of Pd that lead to this reduced fungal diversity, we believe the pattern they report is the result of unbalanced sample sizes, fungal assemblages sampled from bats during and outside the hibernation period, and the comparison of assemblages from different geographic regions.…”

“…Our results, both in Pd-negative hibernacula in 2010 and Pd-positive hibernacula in 2012, are very similar in terms of number and composition of fungal taxa (43 fungal taxa on M. septentrionalis in 2012 with x = 6.0 ± 4.0 SD fungal taxa/bat, n = 16 bats). Nineteen of 44 fungal taxa and 9 of the 10 most common taxa isolated from 3 bat species by Johnson et al (2013) were also found on bats in New Brunswick in 2012 or 2010 (Vanderwolf et al 2013a). Penicillium spp., Cladosporium spp., Pseudogymnoascus pannorum sensu lato, and Mortierella spp.…”

“…This varying pattern of mortality events at Pd-infected bat hibernacula may therefore influence the diversity of fungi that can be cultured from live bats in the immediate aftermath of WNS infection. Johnson et al (2013) found a total of 31 fungal taxa on M. septentrionalis in two Pd-negative hibernacula in Illinois, with a mean of 9.75 ± 1.49 SD fungal taxa per bat (n = 8 bats) and 5.17 ± 4.92 SD (n = 6 bats) respectively. They found 8 fungal taxa on M. sodalis (n = 1 bat) in a Pd-negative Illinois hibernaculum.…”

“…Whether Pd interacts with fungi and bacteria naturally occurring on bats, or whether the microbiome on bats or in hibernacula differs between North America and Europe, is unknown. The few studies on mycobiota present on hibernating bats have shown the composition of fungal taxa is similar between Europe and North America, although sample sizes are generally small and differences in methodology make comparison difficult (Larcher et al, 2003;Voyron et al, 2011;Johnson et al, 2013;Vanderwolf et al, 2013a).…”

“…In the United States, Johnson et al (2013) sampled both Pd-positive and Pd-negative bats and found that the fungal diversity on the former was much lower than on the latter. This led these authors to hypothesize that Pd was responsible for suppressing the normal fungal diversity present on hibernating bats.…”