Dr. Michael Patnode, Washington University, St. Louis: Dietary Plant Polysaccharides Mediate Interactions between Human Gut Microbes in Vivo
Seminar | February 3 | 10-11:30 a.m. | 1205 Berkeley Way West
The development of microbiota-directed foods (MDFs) that selectively promote beneficial human gut microbes requires an understanding of the nutrient acquisition strategies used by targeted microbes and their potential competitors. We screened 34 food-grade dietary fibers in gnotobiotic mice to identify those that selectively target beneficial Bacteroides species in a defined community of human gut microbes. A combination of in vivo forward genetic screens and community-wide bacterial proteomics revealed bioactive carbohydrate components of fibers and nutrient harvesting systems required for expansion of targeted species. Unexpectedly, these results predicted overlap in the use of fiber-derived carbohydrates among targeted and non-targeted community members. Using single- and multi-strain omissions in gnotobiotic mice along with time-series proteomics, we uncovered competition between particular species in vivo, as well as instances of metabolic flexibility that served to mitigate competition. Administration of retrievable artificial food particles, consisting of paramagnetic microscopic beads coated with dietary polysaccharides, disclosed the contributions of individual target Bacteroides species to fiber degradation. Our results define the resource harvesting strategies that underlie, as well as alleviate, competition between Bacteroides and control the selectivity of microbiota-directed dietary interventions.