GUT PHYSIOLOGY The microbiome and gut homeostasis

Changes in the composition of the gut microbiota are associated with many human diseases. So far, however, we have failed to define homeostasis or dysbiosis by the presence or absence of specific microbial species. The composition and function of the adult gut microbiota is governed by diet and host factors that regulate and direct microbial growth. The host delivers oxygen and nitrate to the lumen of the small intestine, which selects for bacteria that use respiration for energy production. In the colon, by contrast, the host limits the availability of oxygen and nitrate, which results in a bacterial community that specializes in fermentation for growth. Although diet influences microbiota composition, a poor diet weakens host control mechanisms that regulate the microbiota. Hence, quantifying host parameters that control microbial growth could help define homeostasis or dysbiosis and could offer alternative strategies to remediate dysbiosis.

Automated summary

Changes in gut microbiota composition are linked to various human diseases. However, defining homeostasis or dysbiosis based on the presence or absence of specific microbial species has been unsuccessful. The adult gut microbiota is regulated by diet and host factors, with oxygen and nitrate availability shaping the bacterial community in different parts of the gut. Poor diet weakens host control mechanisms, potentially leading to dysbiosis. Therefore, quantifying host parameters that control microbial growth could offer alternative approaches to define and remediate dysbiosis.