Effects of diet on resource utilization by a model human gut microbiota containing Bacteroides cellulosilyticus WH2, a symbiont with an extensive glycobiome

The human gut microbiota is an important metabolic organ. However, little is known about how its individual species interact, establish dominant positions, and respond to changes in environmental factors such as diet. In the current study, gnotobiotic mice colonized with a simplified model microbiota composed of 12 sequenced human gut bacterial species were fed oscillating diets of disparate composition. Rapid, reproducible and reversible changes in community structure were observed. Time series microbial RNA-Seq analyses revealed staggered functional responses to diet shifts throughout the community that were heavily focused on carbohydrate and amino acid metabolism. High-resolution shotgun metaproteomics confirmed many of these responses at a protein level. One member, Bacteroides cellulosilyticus WH2, proved exceptionally fit regardless of diet. Its genome encoded more carbohydrate active enzymes than any known Bacteroidetes. Transcriptional profiling indicated that B. cellulosilytic...