Western Bats as a Reservoir of Novel Streptomyces Species with Antifungal Activity

At least two-thirds of commercial antibiotics today are derived fromActinobacteria , more specifically from the genusStreptomyces . Antibiotic resistance and new emerging diseases pose great challenges in the field of microbiology. Cave systems, in which actinobacteria are ubiquitous and abundant, represent new opportunities for the discovery of novel bacterial species and the study of their interactions with emergent pathogens. White-nose syndrome is an invasive bat disease caused by the fungusPseudogymnoascus destructans , which has killed more than six million bats in the last 7 years. In this study, we isolated naturally occurring actinobacteria from white-nose syndrome (WNS)-free bats from five cave systems and surface locations in the vicinity in New Mexico and Arizona, USA. We sequenced the 16S rRNA region and tested 632 isolates from 12 different bat species using a bilayer plate method to evaluate antifungal activity. Thirty-six actinobacteria inhibited or stopped the growth ofP. destructans , with 32 (88.9%) actinobacteria belonging to the genusStreptomyces . Isolates in the generaRhodococcus ,Streptosporangium ,Luteipulveratus , andNocardiopsis also showed inhibition. Twenty-five of the isolates with antifungal activity againstP. destructans represent 15 novelStreptomyces spp. based on multilocus sequence analysis. Our results suggest that bats in western North America caves possess novel bacterial microbiota with the potential to inhibitP. destructans .IMPORTANCE This study reports the largest collection of actinobacteria from bats with activity againstPseudogymnoascus destructans , the fungal causative agent of white-nose syndrome. Using multigene analysis, we discovered 15 potential novel species. This research demonstrates that bats and caves may serve as a rich reservoir for novelStreptomyces species with antimicrobial bioactive compounds.