Study of the Intestinal Microbiota

The intestinal microbiota is the set of numerous microorganisms (between 1012 and 1014 bacteria, viruses, parasites, and non-pathogenic fungi) that live in our digestive tract, mainly in the small intestine and colon. Like a fingerprint, the intestinal microbiota is unique to each individual. However, there is a common core of 15-20 species present in all humans, responsible for the essential functions of the microbiota. Recent techniques for high-throughput sequencing of genetic material and metabolomics (i.e., the global analysis of the elements produced by the microbiota) have made it possible to more precisely describe the relationships between microorganisms and the host and how each influences the functioning of the body. Thus, we now know that the microbiota plays a role in digestive, metabolic, immune, and neurological functions. Certain events will modify the microbiota in a more or less lasting way: illnesses, medical treatments, diet, lifestyle. And these changes to the microbiota can, in turn, influence the body's behavior. As a result, dysbiosis-a quantitative, qualitative, or functional alteration of the microbiota-is a serious avenue for explaining certain pathologies. This topic has become central to biological and medical research, as evidenced by the growing number of scientific publications since the 2010s. Scientists are trying to explore the bidirectional links between dysbiosis and pathologies. They are also trying to explore therapeutic avenues: how to modulate the microbiota to maintain it, bring it closer to, or restore its "normal" configuration to limit the impact of dysbiosis? Research has yielded encouraging results: fecal transplantation (instilling a sample of normal microbiota from the feces of healthy donors into a sick person) or new-generation probiotics with protective biological effects.