Bacterial metabolism and competition in the mammalian gut: Dr. Ashley Wolf, Washington University School of Medicine

Seminar | February 10 | 10-11:30 a.m. | 1205 Berkeley Way West

 Center for Computational Biology, Public Health, School of

Abstract: To manipulate the microbiota and impact human health, we must understand how specific metabolites and interspecies nutrient competition influence microbial abundance and metabolism. Maillard reaction products, which are common in processed foods, form upon heat-induced reaction of amino acids with reducing sugars and include products with deleterious health effects. We fed gnotobiotic mice, colonized with 54 phylogenetically-diverse human gut bacterial strains, defined sugar-rich diets containing whey as the sole protein source or a matched amino acid mixture. In vivo and in vitro mechanistic studies disclosed that whey or fructoselysine, an MRP in whey and many processed foods, selectively increases C. intestinalis absolute abundance, decreases C. aerofaciens abundance, and induces expression of genomic loci that direct import and metabolism of fructoselysine to innocuous products. We further identified a role for differential catabolite repression as a modulator in interspecies nutrient competition. C. aerofaciens represses fructoselysine utilization in the presence of glucose and fructoselysine, but C. intestinalis does not, potentially leading to improved fitness for C. intestinalis in the mixed nutrient environment of the gut. Our identification of a dietary metabolite that specifically impacts gut microbiota composition provides mechanistic knowledge that may influence rational design of microbial-targeted therapies. Our findings suggest that increased consumption of processed foods may influence microbiota composition, and that bacteria are capable of consuming and degrading potentially toxic processed food modifications.