Benjamin Ross

The bacteria resident in the human gastrointestinal tract (the gut microbiota) potently influence diverse aspects of human health, including immunity. However, the forces that govern the composition of the gut microbiota are poorly understood. Our work focuses on a mechanistic, ecological, and evolutionary understanding of how interbacterial interactions between members of the dominant Gram-negative bacteria in the gut, the Bacteroidales, modulate the composition of the microbiota. The Bacteroidales utilize a contact-dependent toxin-delivery system known as the type VI secretion system (T6SS) to kill neighboring cells. We study the impact of this pathway on the microbiota and how bacteria adapt to defend against T6SS-mediated antagonism, using a combination of bacterial genetics, biochemistry, metagenomics, and germ-free mouse models. We are also interested in understanding why Bacteroidales abundance is depleted in individuals with cystic fibrosis, with the goal of improving health through restoration of these bacteria.