That gut instinct! Novel insights in the interplay between the microbiota, serotonin metabolism and gut function

Bacteria are all around us and they even inhabit our gastrointestinal tracts, where they help us digest the food we eat. In recent years, the research into human-microbe interactions is getting increasingly noticeable, allowing us to better understand this amazing interactive environment. 

Gut bacteria are living organisms, just as humans or animals, and they need nutrients for their survival. In our gut, these bacteria get the necessary nutrients from the food we eat. A portion of the nutrients gut bacteria consume are transformed into messenger molecules, which in turn, induce chemically-mediated interactions between gut microbiota and the gut. For example, the beneficial members of this community can produce valuable products that can keep our intestinal immune system healthy, so that no bad bacteria can spread around and cause unwanted side effects, such as diarrhea or other intestinal disorders.

In this thesis research, we studied how gut bacteria interact with 5 hydroxytryptophan, which is the natural precursor of the hormone of happiness, serotonin. We showed how 5 hydroxytryptophan can be metabolized by the gut bacteria to an indole derivative, 5 hydroxyindole. This bacterial product affected gut motility, and had a marginal effect on the microbiota composition. In parallel, we uncovered that specific gut bacteria can metabolize serotonin to 5-hydroxyindoleacetic acid. Our research also suggested that the metabolization process (serotonin -> 5-hydroxyindoleacetic acid) might have an impact on both the bacterial fitness and on the enhancement of the intestinal epithelial barrier integrity.

Dissertation: http://hdl.handle.net/11370/7c09599d-eecf-4bb9-bfd5-639798cf6c4c