Individualized Responses of Gut Microbiome to Diet and Their Role in Gastrointestinal Physiology

Germ-free mouse isolators

The germ-free mouse facility allows lab members to deconstruct a complex system and mechanistically address the role of gut bacteria in maintaining health and causing disease.

Dr. Kashyap's Gut Microbiome Lab is investigating how different microbiomes — modeled in germ-free mice — respond to dietary interventions, and the effects of diet-induced changes in the gut microbiome on gastrointestinal physiology. To do this, the team is examining how environmental factors, including diet, can modify the relationship between gastrointestinal motility and the gut microbiota.

Scientists know that diet may impact motility directly, via changes in the bulk flow of material through the gut, or indirectly, through an impact on the microbiota. Dietary polysaccharides are a major fuel for the distal gut microbial community; thus, gut microbiomes have a large repertoire of carbohydrate-degrading genes. Dietary fermentable polysaccharides can alter microbiota composition, in part, because community members differ in their ability to metabolize them.

Additionally, different bacteria produce different fermentation end products when metabolizing a specific carbohydrate. Changes in production of short-chain fatty acids, such as butyrate, can influence diverse aspects of host physiology, including motility.

A part of this project is examining the relationship between diet, gut microbiota and gastrointestinal physiology to better understand responses in diseases such as irritable bowel syndrome (IBS) and obesity. Patients with IBS often report food sensitivities and avoid one or more food groups that seem to worsen their symptoms. The Gut Microbiome Lab seeks to develop individualized dietary therapies for management of gastrointestinal motility disorders such as IBS and for metabolic disorders such as obesity.

Diet and gut microbiota

Dr. Kashyap provides a summary of the research published in "Individualized responses of gut microbiota to dietary intervention modeled in humanized mice" by Samuel A. Smits, Angela Marcobal, Steven Higginbottom, Justin L. Sonnenburg and Purna C. Kashyap.