Composition and Function of the Gut Microbiome

The human gastrointestinal tract harbors a plethora of microorganisms, most of which belong to the domain Bacteria. Owing to manifold effects on host physiology and host health, there is a growing interest in better understanding the role and function of gut microbial communities. Microbiota composition changes along the gastrointestinal tract in response to changes in the physicochemical conditions and substrate availability. Moreover, large interindividual differences are observed. One major function of the gut microbiota lies in the conversion of indigestible dietary carbohydrates and host-derived glycans to short-chain fatty acids, which provide energy to the host and have regulatory functions. Microbiome analysis has led to the notion of a “core microbiome” which encodes functions shared by human individuals. Gut microbial community members interact with each other and with the host constituting a functional microbial ecosystem. However, there are still major gaps in our understanding of the molecular mechanisms underlying such interactions.