Genome sequencing creates first reference data for microbes living with healthy adults
Microbes inhabit just about every part of the human body, living on the skin, in the gut, and up the nose. Sometimes they cause sickness, but most of the time, microorganisms live in harmony with their human hosts, providing vital functions essential for human survival. For the first time, a consortium of researchers organized by the National Institutes of Health has mapped the normal microbial makeup of healthy humans, producing numerous insights and even a few surprises. The human body contains trillions of microorganisms — outnumbering human cells by 10 to 1. Because of their small size, however, microorganisms make up only about 1 to 3 percent of the body’s mass (in a 200-pound adult, that’s 2 to 6 pounds of bacteria), but play a vital role in human health.
Researchers found, for example, that nearly everyone routinely carries pathogens, microorganisms known to cause illnesses. In healthy individuals, however, pathogens cause no disease; they simply coexist with their host and the rest of the human microbiome, the collection of all microorganisms living in the human body. Researchers must now figure out why some pathogens turn deadly and under what conditions, likely revising current concepts of how microorganisms cause disease.