Prof. Dr. Eric Martens (University of Michigan Medical School)

Biological Colloquium of the Christian-Albrechts-University Kiel

Monday, 14th October 2019, 4:15 pm

Center for Molecular Biosciences (ZMB)
Seminar room 4th floor
Am Botanischen Garten 11

As guest of the CRC 1182

Prof. Dr. Eric Martens

University of Michigan Medical School

Talks about:

Complex carbohydrate metabolism by human gut bacteria in health and disease

Colonic bacteria are responsible for nearly all of human dietary fiber digestion. Despite the accepted health benefits of consuming dietary fiber, little is known about the precise mechanisms by which fiber levels impact the gut microbiota and alter disease risk or how the precise chemistry of fiber polysaccharides interfaces with the hundreds of gut microbiota species. Using gnotobiotic mouse models, functional genomics, biochemical and genetic studies we have explored these interactions in mechanistic depth. One of the prominent groups of human gut bacteria (Bacteroidetes) deploy their armament of fiber-degrading enzymes in genomically linked “polysaccharide utilization loci” (PULs). Work in my lab, or by others, has identified PULs for degradation of nearly all known terrestrial fiber polysaccharides and secreted host glycans. In addition, some PULs involved in degradation of seaweed polysaccharides have also emerged in human gut bacteria and appear to have been laterally transferred from oceanic Bacteroidetes or fish intestinal symbionts. In recent studies in which animals were colonized with a synthetic human gut microbiota composed of fully sequenced commensal bacteria, we have elucidated the functional interactions between dietary fiber, the gut microbiota and the colonic mucus barrier, which serves as a primary defense against enteric pathogens. During chronic or intermittent dietary fiber deficiency, the gut microbiota resorts to host-secreted mucus glycoproteins as a nutrient source, leading to erosion of the colonic mucus barrier. Dietary fiber deprivation, together with a fiber-deprived, mucus-eroding microbiota, promotes greater epithelial access and lethal colitis by the mucosal pathogen, Citrobacter rodentium, or inflammatory disease in the absence of pathogen in IL-10-deficient mice. Our work has begun to unravel the intricate pathways linking diet, the gut microbiome and intestinal barrier dysfunction, which could be exploited to improve health using dietary fiber or prebiotic therapeutics.