The WormFood CURE: Screening for bioactive metabolites that antagonize the Caenorhabditis elegans Ras signaling pathway

Abstract

Course-based Undergraduate Research Experiences (CUREs) provide an accessible, scalable platform for scientific discovery. Here, we present the WormFood CURE, which mines environmental bacterial isolates for bioactive secondary metabolites using Caenorhabditis elegans phenotype suppression as a functional readout. Utilizing the multivulva (Muv) phenotype, our pilot cohort interrogated 41 wild bacterial isolates for suppression of Ras/MAPK signaling. We identified one Bacillus safensis isolate BAC-08 and one Bacillus altitudinis isolate BAC-44 that significantly inhibited ectopic vulval precursor cell (VPC) induction in Muv strains when fed as a live food source. BAC-08 and BAC-44 also significantly affected wild-type nematode development and growth. Metabolic pathway reconstruction from annotated genome assemblies did not support nutritional deficiency as the potential mechanism; instead, we observed that methanol-soluble intracellular extracts from BAC-44 were sufficient to inhibit pseudovulvae growth. We concluded that the observed Muv suppression is likely driven by a secondary metabolite effect. Comparative genomic analysis further identified unique biosynthetic gene clusters (BGCs) present in both BAC-08 and BAC-44 isolates compared to the other isolated Bacillus species. Altogether, our study demonstrates that the WormFood CURE model successfully identifies novel bacterial-genetic interactions, providing a scalable platform for discovery of new natural microbial products that modulate conserved eukaryotic signaling pathways.