Image: Bacteria
United States Department of Agriculture
A "map" of all of the microbes on the human body could help to treat disease. Entercoccus faecalis, a microbe that lives in the human gut, appears above.
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updated 12/1/2009 12:56:59 PM ET 2009-12-01T17:56:59

The 100 trillion microbes that reside in and on our bodies are distributed into distinct neighborhoods, according to new research.

Sampling 27 different internal and external sites across the body, researchers from the University of Colorado at Boulder have developed the most detailed atlas of human microbial bacteria, collectively known as the human microbiome, to date.

This baseline bacterial atlas is a significant step toward learning how to treat or manipulate the microbial communities on the body to solve important health problems, such as skin disorders.

The study, published in Science, found that not only does bacterial distribution change from person to person, but also that bacterial species selectively congregate on certain body parts.

For example, Propionibacteria thrive in the oily microenvironments on the forehead, hair and external nose, while Staphylococcus prefer the danker regions of the armpits and bottoms of the feet.

Rob Knight, assistant professor of biochemistry at the University of Colorado at Boulder and lead author of the study, notes that he can't explain why skin chemistry has such a significant effect on bacterial growth, but follow-up studies are underway.

Over four months, the researchers swabbed the sample sites from a pool of nine healthy adults four separate times. They also transplanted local and foreign bacteria to different body parts to test how the microbes fared in various microenvironments.

By identifying and mapping this range of bacteria, Knight and his colleagues hope to establish a baseline for a healthy human microbiome, which can then be applied to disease prevention.

"When we have equivalent samples from sick people, we would be able to start developing markers that could let you predict that you were developing a disease, either because of the bacteria themselves, or because the bacteria provide a sensitive readout of the underlying conditions, before symptoms appear," Knight told Discovery News.

Until then, there are still many questions about the physiological interactions among these microbes and the human body.

"Most of the microbes living on our skin are harmless and don't cause any problems," said Elizabeth Grice, post-doctoral fellow at the National Institutes of Health who has studied bacterial diversity on skin. "Yet, we don't understand the role of these microbes in skin health or disease."

© 2012 Discovery Channel

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