Winnipeg Free Press - PRINT EDITION

We're one-tenth human

Rest of the body is a swarm of foreign microbes

  • Print
WASHINGTON -- Scientists are beginning a large-scale effort to identify and analyze the vast majority of cells in or on your body that aren't of human origin.

Only about 10 per cent of the trillions of cells that make up a person are truly human, researchers say. The other 90 per cent are bacteria, viruses and other microbes swarming in your gut and on your skin.

"We really are a superorganism," Brett Finlay, a microbiologist at the University of British Columbia in Vancouver, said in an email. "From the moment we are born until we die, we live in a symbiotic relationship with our microbes."

"At birth, babies emerge from a sterile environment into one that is laden with microbes," said Laurie Comstock, a microbiologist at Harvard Medical School in Boston. "The infant's intestines then rapidly become home to one of the densest populations of bacteria on Earth."

Most of these microbes are harmless, researchers say. Many are necessary to life and health. A troublesome minority, however, can cause everything from teenage acne and obesity to autism and cancer.

The National Institutes of Health has launched a $115-million, five-year project to identify, analyze and catalog hundreds of microbial species resident in or on the human body.

Called the Human Microbiome Project, it's modelled after the Human Genome Project, which decoded most of the human genes in the 1990s. The first 35 microbiome research grants took effect this summer.

"The composition of the complex microbial communities inhabiting the human body has a tremendous influence on human health and disease," said Richard Gibbs, a leading human genome researcher at the Baylor College of Medicine in Houston. Gibbs received a grant to sequence the genes of 400 bacterial strains by 2011.

The goal of the microbiome project, which is international in scope, is to identify which microbes are harmful and to figure out ways to prevent or treat diseases they cause.

It's a bewildering task, because scientists estimate there are about 1,000 different species of microbes living in the human gut and about as many more separate species on human skin.

The microbes form tiny colonies of bacteria that settle in different areas of the body. Jeffrey Gordon, a microbiologist at the University of Washington in St. Louis, likened them to "ecosystems," similar to those that plants and animals form on islands on Earth.

The most popular site for human skin microbes, surprisingly, is the forearm, which is home to 44 different microbial species, according to a recent study by Julia Segre, a microbiologist at the National Human Genome Research Institute in Bethesda, Md. The most barren region is behind the ear, where only 15 species typically settle, she reported in the journal Science last May.

"Hairy moist underarms lie a short distance from dry forearms, but these two niches are as ecologically dissimilar as rainforests are to deserts," Segre said.

Different tribes of microbes are associated with different maladies. For example, bacteria associated with the skin disease psoriasis favour the outer elbow, Segre reported. Eczema bugs prefer the inner elbow.

Microbes also vary between people. Matthias Tschoep, an obesity expert at the University of Cincinnati's College of Medicine, identified 383 microbial genes that differed significantly between pairs of obese and slender twins. Microbes in obese people harvest sugars and fats in the diet more efficiently than do others on slender people, he reported in Nature.

"It is possible that drug targets or drug candidates for the treatment of obesity could be identified from the obesity-associated microbiome," Tschoep said.

At the Conference on the Beneficial Effects of Microbes held in San Diego last fall, scientists described many ways in which microbes can be helpful -- even essential -- to humans.

Bacteria in the gut make it possible to digest food, synthesize vitamins, remove toxins and develop the immune system after birth.

One of the new human microbiome grants went to Robert Modlin, a dermatologist at the University of California, Los Angeles, to study microbes lurking under the skin that cause 17 million Americans -- including 80 per cent of those age 12 to 24 -- to suffer from acne.

"Success may lead to the development of new, effective therapeutic strategies for treatment of acne," Modlin's grant announcement declared.

-- McClatchy-Tribune Information Services

Republished from the Winnipeg Free Press print edition September 13, 2009 B3

Fact Check

Fact Check

Have you found an error, or know of something we’ve missed in one of our stories?
Please use the form below and let us know.

* Required
  • Please post the headline of the story or the title of the video with the error.

  • Please post exactly what was wrong with the story.

  • Please indicate your source for the correct information.

  • Yes

    No

  • This will only be used to contact you if we have a question about your submission, it will not be used to identify you or be published.

  • Cancel

Having problems with the form?

Contact Us Directly
  • Print

You can comment on most stories on winnipegfreepress.com. You can also agree or disagree with other comments. All you need to do is be a Winnipeg Free Press print or e-edition subscriber to join the conversation and give your feedback.

You can comment on most stories on winnipegfreepress.com. You can also agree or disagree with other comments. All you need to do is be a Winnipeg Free Press print or e-edition subscriber to join the conversation and give your feedback.

Have Your Say

New to commenting? Check out our Frequently Asked Questions.

Have Your Say

Comments are open to Winnipeg Free Press print or e-edition subscribers only. why?

Have Your Say

Comments are open to Winnipeg Free Press Subscribers only. why?

The Winnipeg Free Press does not necessarily endorse any of the views posted. By submitting your comment, you agree to our Terms and Conditions. These terms were revised effective April 16, 2010.

letters

Make text: Larger | Smaller

LATEST VIDEO

Your top TV picks for this week - December 8-12

View more like this

Photo Store Gallery

  • Marc Gallant / Winnipeg Free Press. Local- Deer in Canola field near Elma, Manitoba. 060706.
  • PHIL.HOSSACK@FREEPRESS.MB.CA 101130-Winnipeg Free Press Columns of light reach skyward to the stars above Sanford Mb Tuesday night. The effect is produced by streetlights refracting through ice crystals suspended in the air on humid winter nights. Stand Up.....

View More Gallery Photos

Poll

Now that former cabinet minister Theresa Oswald has entered the NDP leadership race, do you believe the "gang of five" rebel ministers were right to publicly criticize Premier Greg Selinger's leadership?

View Results

Ads by Google