Chemical Biology of Ant-Associated Defensive Bacteria

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 DESCRIPTION (provided by applicant): The need for new antibiotics continues to grow more dire. Natural products from microbial sources have supplied the major pipeline for novel antibiotics, but traditional discovery efforts have yielded diminishing returns over the last severl decades, necessitating new approaches. This proposal uses the powerful approach of aligning chemical ecology with natural product discovery, exploiting the highly productive chemistry of bacteria associated with fungus-farming ants. These highly specialized ant-associated bacteria are thought to defend their niche using antibiotics against closely related competitors. The chemical basis of this antagonism has not been explored and is the foundation of this project. The first aim of this project is to screen ant-associated bacteria to identify antibacterial activiy and other chemically mediated interactions. Second, the molecules responsible for this activity will be identified and characterized. Genome sequencing will connect these active molecules to their biosynthetic gene clusters and also reveal which additional clusters are present but "silent" - that is, no corresponding metabolites are observed. These "cryptic" biosynthetic clusters are a near-universal feature of bacterial genomes and are a major opportunity for antibiotic discovery. The third aim uses ecologically inspired co-culturing approaches to supply missing chemical cues that elicit production of some of these "cryptic" metabolites. These chemical inducers of antibiotic production will be identified, tested for general utility, and applied to elicit additioal cryptic metabolites.