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Microbe Census Maps Out Human Body’s Bacteria, Viruses, Other Bugs

June 30, 2012

It gives scientists a reference point of what the microbial community looks like in healthy people, and they plan to use it to study how changes in a person’s microbiome can lead to illness.

After five years of toil, a consortium of several hundred U.S. researchers has released a detailed census of the myriad bacteria, yeasts, viruses and amoebas that live, eat, excrete, reproduce and die in or on us.

Described in two papers in Nature and a raft of reports in other journals, the data released Wednesday describe microbes of the skin, saliva, nostrils, guts and other areas of 242 adults in tiptop health.

The $170-million, federally funded Human Microbiome Project also cataloged the genes contained within this zoo of life. The results shed light on the hum of microbial activity inside us as nutrients are chopped and guzzled, gas and other wastes are expelled, and bugs send chemical messages to one another, jostling for supremacy or attracting new neighbors to help keep their community going.

The research is important because it gives scientists a reference point of what the microbial community looks like in healthy people, and they plan to use it to study how changes in a person’s microbiome can lead to illness. A spate of studies in the last few years has documented potential links to conditions such as inflammatory bowel disease,asthma and obesity.

Each of us is home to about 100 trillion microscopic life forms — a figure that’s about 10 times higher than the number of cells in the human body. In a 200-pound adult, these organisms can weigh a combined 2 to 6 pounds.

The vast majority of our microscopic denizens appear to be bacteria; 10,000 types may choose to make Homo sapienshome, the scientists found.

Some spots on the body, such as the mouth, are rain-forest-like in their diversity, inhabited by a rich community of bacteria that is fairly similar from one person to the next.

Other locations, such as the vagina, are more like monocultures dominated by a single bacterium, though the precise strain can vary from person to person.

“Pretty much every time you look at the results from one of the samples, it’s like a Christmas present, it’s like, ‘Oh, what’s inside?’ ” said microbial ecologist Barbara A. Methe of the J. Craig Venter Institute in Rockville, Md., who worked on both of the Nature studies. “What are all these microbes doing?”

Scientists have been aware that bacteria live on the human body ever since a 17th century Dutch naturalist examined the plaque from his teeth under a microscope. They have long speculated that these tenants exert crucial influence on our health.

Efforts to study the microbes were stymied because only a tiny fraction of bugs can be coaxed to grow in the laboratory. But the rise of sophisticated DNA sequencing technology offered a new approach. In 2001, as the landmark Human Genome Project was wrapping up, researchers proposed it was time to explore our “second genome.”
see the full story here:
http://www.latimes.com/news/science/la-sci-bacteria-20120614,0,5855,full.story

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