Abstract:

Certain groups of marine bacteria are enriched in the ability to produce structurally diverse secondary metabolites. The research conducted in my lab asks: who are these bacteria, where do they live, and why do they make these compounds? The first of these questions is linked to our ability to recognize groups of bacteria that maintain species-like properties. Using phylogenomic approaches, we have identified species-like clades in a model organism and linked them to the production of specific secondary metabolites. These linkages suggest that the compounds represent important functional traits that help distinguish bacterial ecotypes. Likewise, we have acquired evidence that globally distributed species acquire biosynthetic pathways from the local gene pool, thus generating larger than expected species-level biosynthetic diversity. Finally, although the functions of these compounds remain poorly understood, we can distinguish closely related clades that differentially invest in interference vs. exploitation competition, with the former mediated by secondary metabolism. These compounds do not exclusively function in defense, as evidenced by our recent finding that a redox-active compound is up regulated under low oxygen conditions. There is evidence that this compound functions as an extracellular electron shuttle and, surprisingly, is an intermediate in a pathway that produces a potent antibiotic when oxygen is readily available. Thus, the products of a single pathway shift depending upon environmental conditions resulting in products that have dramatically different ecological functions. While exploiting these compounds for useful purposes is an additional goal of our research, addressing fundamental ecological and evolutionary questions has provided surprising new insight that has aided our discovery efforts.