THE MICROBIOME: A MEDIATOR OF HUMAN WELLNESS

The human microbiome refers to the millions of genes contained in the genomes of tens of trillions of microbes inhabiting the exposed surfaces of our bodies. Our microbial communities are dominated by bacteria; other microbes are also represented. Understanding of the microbiome has expanded dramatically through the application of advanced technologies—particularly culture-independent DNA sequencing and computational analytics. Mounting evidence indicates its important roles in human health and disease. We review a small but significant fraction of available knowledge, focusing initially on the de novo perinatal acquisition of bacterial communities, their maturation over time, and their variation among habitats and between individuals. We emphasize the intestinal (gut) habitat—wherein bacteria are major determinants of the organ's postnatal maturation and physiological functions, including its immune system. Early exposure to certain microbes may decrease subsequent human susceptibility to allergic and autoimmune conditions. Gut bacteria facilitate the processing of key dietary constituents and, among other effects, impact drug metabolism. Differences in gut bacterial communities appear to contribute to obesity and may also promote gastroesophageal reflux and other intestinal disorders. Additional research on microbiome manipulations may well yield novel preventive strategies and treatments.