Inhibition of Pseudogymnoascus destructans Growth from Conidia and Mycelial Extension by Bacterially Produced Volatile Organic Compounds

Abstract

The recently identified causative agent of white-nose syndrome (WNS), Pseudogymnoascus destructans, has been implicated in the mortality of an estimated 5.5 million North American bats since its initial documentation in 2006 (Frick et al. in Science 329:679-682, 2010). In an effort to identify potential biological and chemical control options for WNS, 6 previously described bacterially produced volatile organic compounds (VOCs) were screened for anti-P. destructans activity. The compounds include decanal; 2-ethyl-1-hexanol; nonanal; benzothiazole; benzaldehyde; andN,N-dimethyloctylamine. P. destructans conidia and mycelial plugs were exposed to the VOCs in a closed air space at 15 and 4 °C and then evaluated for growth inhibition. All VOCs inhibited growth from conidia as well as inhibiting radial mycelial extension, with the greatest effect at 4 °C. Studies of the ecology of fungistatic soils and the natural abundance of the fungistatic VOCs present in these environments suggest a synergistic activity of select VOCs may occur. The evaluation of formulations of two or three VOCs at equivalent concentrations was supportive of synergistic activity in several cases. The identification of bacterially produced VOCs with anti-P. destructans activity indicates disease-suppressive and fungistatic soils as a potentially significant reservoir of biological and chemical control options for WNS and provides wildlife management personnel with tools to combat this devastating disease.

Microbial inhibitors of the fungus Pseudogymnoascus destructans, the causal agent of white-nose syndrome in bats

“…[19]. These microbes are being studied for their biocontrol potential, and our study adds nearly 150 candidate biocontrol agents to this list, Additionally, we expand the list of natural products [18,20–23] that could be of potential use in controlling P . destructans in bat caves.…”

White-Nose Syndrome in Bats

“…Several studies have examined the efficacy of treating bats with anti-fungal chemicals, such as terbinafine, but none have shown any promise. There has also been interest in alternative forms of treatment, including use of naturally occurring bacteria (Fritze et al 2012;Hoyt et al 2015) or volatile compounds (Cornelison et al 2014). Recent work by Cornelison et al (2014) showed that a volatile organic compounds (VOCs) inhibited growth of P. destructans in vitro.…”

“…There has also been interest in alternative forms of treatment, including use of naturally occurring bacteria (Fritze et al 2012;Hoyt et al 2015) or volatile compounds (Cornelison et al 2014). Recent work by Cornelison et al (2014) showed that a volatile organic compounds (VOCs) inhibited growth of P. destructans in vitro. Similarly, a recent study by Hoyt et al (2015) showed that Pseudomonas bacteria that naturally occur on hibernating bats inhibit growth of P. destructans in vitro.…”

Success of Wildlife Disease Treatment Depends on Host Immune Response

“…Advances in antibiotics, fungicides, and probiotics make effective treatment of wildlife diseases more achievable than ever. However, while lab experiments or short-term field trials may produce promising results (e.g., Cornelison et al, 2014), deployment of a given treatment strategy may have unforeseen negative consequences on the host population, especially if host response to the pathogen (or its removal) is not considered in advance. Therefore, it is critical to fully evaluate host-pathogen interactions prior to the deployment of a treatment strategy.…”

“…The fungus colonizes bats during an immunosuppressed torpor, but while European bats tolerate infection (Puechmaille et al, 2011), naïve North American bats experience a disruption of physiological homeostasis leading to measureable population declines (Willis et al, 2011;Verant et al, 2014). Severity of these declines has created a sense of urgency for conservation intervention in the form of chemical or biological control (e.g., fungistatic volatile organic compounds; Cornelison et al, 2014), probiotics (e.g., Cheng et al, 2016), or synthetic compounds (e.g., Raudabaugh and Miller, 2015) to either prevent pathogen exposure to naïve populations or reduce disease intensity in infected populations.…”