FUNGI AS SOURCES OF SMALL MOLECULE INHIBITORS OF BOTULISM NEUROTOXINS
Bacterial Foodborne Pathogens & Mycology Research Unit
2012 Annual Report
1a.Objectives (from AD-416):
Discover and develop potent, safe and soluble inhibitors of botulinum neurotoxins (BoNTs).
1b.Approach (from AD-416):
Microfungal colonists (fungicolous fungi) of long-lived fungal sporocarps collected in forested habitats within the continental USA and Hawaii were isolated into pure culture. Individual fungi are grown in both liquid and solid culture fermentation and extracted with organic solvents. Extracts containing fungal produced compounds that neutralize botulism, in assays performed by USAMRIID, will be delivered to a cooperating chemist at the University of Iowa for isolation and characterization of the bioactive compound(s). Cultures producing compounds that neutralize botulism neurotoxins will be identified based on morphological characteristics and DNA sequencing of the internal transcribed spacer (ITS) region and domains D1 and D2 of the nuclear large subumit (28S) rDNA geme and comparison with sequences deposited in GenBank (National Center for Biotechnology Information). Viable cultures of the small molecule producing fungal strains of interest will be maintained.
Fungi that colonize and kill other fungi are potential sources of novel antifungal agents and other compounds useful to agriculture or medicine. Several antifungal compounds “bis-naphthopyrones” were isolated from fungi isolated as colonists of other fungi. Bioassays performed at USAMRIID have identified three of these compounds as inhibitors of botulinum neurotoxin serotype A which causes a life-threatening neuroparalytic illness known as botulism. These are the first fungal natural products reported to exhibit botulinum neurotoxin serotype A inhibitory activity.