Mechanisms underlying bacterial fitness in the intestine

A central challenge in microbiome science is defining how individual bacterial species achieve ecological fitness in the gut and how strain-level variation shapes host physiology. Phocaeicola vulgatus (Pvu) is a highly prevalent, early-life colonizer of the human intestine that exhibits exceptional competitive fitness, yet its mechanisms of persistence and host interaction remain poorly understood. Pvu has been repeatedly associated with metabolic disorders and inflammatory bowel disease, where it appears capable of either exacerbating or protecting against inflammation depending on context. However, causal mechanisms are obscured by limited genomic annotation and sparse characterization of strain-level diversity. We are working to define the genetic and phenotypic diversity within the Pvu species complex, identifying the genes, pathways, and metabolites that govern gut colonization and inflammatory potential. We also seek to understand how microbial competition and inflammation alter Pvu’s fitness landscape along the intestinal tract. The outcomes of this work are laying the foundation for strain-specific prognostic markers and microbiome-directed therapeutic strategies to reduce inflammatory disease risk and severity.