THE HUMAN MICROBIOME
The human microbiome is a complex ecosystem that includes all the microorganisms that reside on the surface and deep within. These organisms are researched, characterized, and organized by the National Insitute of Health's (NIH) Human Microbiome Project. Explore this page to learn more about the human microbiome, the HMP, and examine an interactive.
THE HUMAN MICROBIOME
The Human Microbiome is the collection of all the microbes within the human body.
These microorganisms include a variety of eukaryotes, archaea, bacteria and viruses. In an average human adult, microbes outnumber their host 10 to 1. However, due to their size, microbes make up only about 1 to 3 percent of our body mass (around 2 to 6 pounds in a 200 pound adult). These organisms are by and large not harmful to their host, in fact most are crucial for maintaining health. For example, some produce vitamins that the human body cannot make, break down food to extract nutrients, and assist the immune system in defending the body.
A variety of microbes inhabit different areas of the human body. Bacteria in the digestive tract, collectively referred to as the gut flora, can digest certain nutrients that humans otherwise could not breakdown. Most of these are anaerobes, meaning they survive in an environment that lacks oxygen. Others, such as Actinomyces viscosus and A. naeslundii, reside within the mouth, where they contribute to plaque. Archaea, such at methanogens, also are present in the human body, but the number of archaeal species is much more limited. Furthermore, fungi, specifically those of the Candida and Malassezia species, can be found. These microbes have the ability to become pathogenic in immunocompromised hosts.