Isolation of Antagonistic Bacterial Strains and Their Antimicrobial Volatile Organic Compounds Against Pseudogymnoascus destructans in Rhinolophus ferrumequinum Wing Membranes.

White-nose syndrome (WNS), caused by the fungus Pseudogymnoascus destructans (Pd), has led to significant mortality and species endangerment in North America. Bats in eastern China, however, carry low loads of Pd and do not exhibit disease, suggesting natural resistance. To explore potential defenses, we isolated and screened antagonistic bacteria from the wing membranes of Rhinolophus ferrumequinum for their ability to inhibit Pd growth. We employed the plate delineation isolation method to obtain 74 single strains, which were then screened for antagonistic effects through contact and non-contact inhibition experiments. A total of 18 antagonistic strains were isolated. After sequencing and comparison with the NCBI database, we identified eight known species and three unidentified species of antagonistic bacteria: Pseudomonas carnis, Buttiauxella ferragutiae, Paraburkholderia fungorum, Arthrobacter rhombi, Serratia liquefaciens, Paeniglutamicibacter gangotriensis, Brevibacterium aurantiacum, Acinetobacter lactucae, Pseudomonas sp., Brevibacterium sp., and Acinetobacter sp. Seventeen isolated strains showed varying degrees of inhibition by contact, while five species, including P. carnis, B. ferragutiae, S. liquefaciens, P. gangotriensis, and Brevibacterium sp., also inhibited Pd via non-contact mode. We utilized solid-phase microextraction coupled with GC-MS to obtain approximately 20 volatile compounds, all of which exhibited inhibitory effects on the growth of Pd, including ketones, aldehydes, and sulfur ethers. Notably, 5 ppm of 1-undecene, dimethyl trisulphide, and 2-nonanone each independently inhibited Pd growth. These findings suggest that the antagonistic strains and their VOCs might help protect bats from WNS. Understanding the interactions between Pd and skin flora, along with their VOCs, may be crucial in mitigating bats' vulnerability to WNS and developing effective mitigation strategies in the future.