Abstract
The term microbiome refers to the genetic material of the catalog of microbial taxa associated with humans. As in all ecosystems, the microbiota reaches a dynamic equilibrium in the human body, which can be altered by environmental factors and external stimuli. Metagenomics is a relatively new field of study of microbial genomes within diverse environmental samples, which is of increasing importance in microbiology. The introduction of this ecological perception of microbiology is the key to achieving real knowledge about the influence of the microbiota in human health and disease. The aim of this review is to summarize the link between the human microbiota (focusing on the intestinal, vaginal, skin, and airway body sites) and health from this ecological point of view, highlighting the contribution of metagenomics in the advance of this field.