Open Access Senior Thesis
Bachelor of Arts
Ethan Van Arnam
There is an urgent and growing need for novel antibiotics with the growing prevalence of antibiotic-resistant pathogens. Ecologically-guided discovery is a strategy that focuses on how and where specially evolved metabolites such as antibiotics are used in nature. This strategy reveals unique active molecules with potential for human use. An unexplored niche with great potential for antibiotic discovery exists with Southwestern fungus-farming Trachymyrmex ants and their Actinobacteria symbionts. In exchange for nutrients from the ant, the ants’ bacterial symbiont produces antifungal molecules that protect the ants’ fungal cultivar from invasion by pathogenic microorganisms. They also produce antibacterial molecules to protect themselves from niche competitors. Recently, new antibiotics have been isolated from Trachymyrmex ant symbionts collected in the southwestern U.S., such as a novel analog of the antibiotic nocamycin and an antifungal compound, ECO-0501. These findings suggest that this unique environment may yield additional novel metabolites. Reported here are discoveries from a large-scale and systematic analysis of symbiont-derived natural products from this niche to understand their distribution and discovery potential, with the goal of discovering and characterizing novel bioactive compounds. We have assembled a collection of Actinobacteria isolated from colonies of Trachymyrmex ants in Arizona, New Mexico, and New York. An extract library has been prepared from this collection, and antibiotic activity testing of that library indicates the presence of ecologically and clinically relevant active compounds. Metabolomics data reveals patterns with regards to ant genus and the metabolites present in crude extracts. This method has great potential for strain prioritization in future studies.
Hansen, Katherine, "Biogeography of Special Metabolites Produced by Ant-Associated Bacteria" (2023). Scripps Senior Theses. 2149.