Gut check finds plenty of bacteria

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Gut check finds plenty of bacteria

San

January 23, 2006 - 2:14AM

Scientists have discovered that the human stomach - a nasty, highly

acidic place - is home to a surprising variety of bacteria, including

a close relative of a bug that lives in radioactive waste sites, hot

springs and animal poop.

In samples from the stomach linings of 23 people, they found at least

128 different types of bacteria, 10 per cent of them previously unknown.

They also found that the mix of bacteria varies greatly from person

to person, and that conventional tests for Heliobacter pylori - a

germ that causes ulcers, stomach cancer and other gastric distress -

failed to identify it in 7 out of 19 people.

The report in the online edition of the Proceedings of the National

Academy of Sciences lends weight to the view that microbes are a

vital and intrinsic part of the human body.

" We are at a period of time that's very exciting, where we can have a

much more transcendent view of ourselves as life forms, " said

I Gordon, director of the Center for Genome Sciences at the

University of Washington in St Louis, who was not involved in the study.

In that view, he said, people are " superorganisms " made up of human

cells and microbial cells - and the microbes outnumber our own cells

10 to one.

The study also overturns conventional wisdom about the stomach. With

its strong acids and enzymes for breaking down food, it was thought

to be a barren, almost sterile place where no respectable microbe

would choose to live.

The stomach was considered " an acid waste pit, " said Dr Relman

of Stanford University and the Veterans Affairs Palo Alto Health Care

System, who was part of the study led by research associate beth

Bik.

" It would burn you if you stuck your finger in something that strong. "

He said the discovery of bacteria that cause ulcers, which earned

Australian scientists Barry Marshall and Robin Warren this year's

Nobel Prize in physiology or medicine, did little to change that view

because those germs were thought to have unique ways of coping with

the stomach's harsh environment.

Relman's lab is one of a handful probing the microbial ecosystems of

the human body.

Scientists have known for years that bacteria in the gut - known as

the intestinal microflora - help us digest food. Taking antibiotics

can kill off this microbial community and cause digestive misery.

More recently they've come to suspect that other parts of the body

have their own natural blends of microbes; that throwing this balance

off-kilter can cause illness; and that chronic infections could

contribute to diseases such as diabetes, Alzheimer's disease,

rheumatoid arthritis, atherosclerosis, chronic prostate infections

and bowel inflammations.

In April, a study led by Dr Eckburg of the Relman lab found 395

species of microbes living in the human colon. Most of those bugs

were unknown to science. Some cling to the intestinal wall; others

hitch rides on bits of undigested food, forming colonies that

researchers jokingly called " Whovilles, " after those in the Dr Seuss

book " Horton Hears a Who! "

The lab is now looking at bacterial communities in the mouth, taking

samples from the gums, the top and bottom of the tongue, teeth and

palate. It's also investigating the role of microbes in Crohn's

disease, a chronic bowel inflammation.

And it's probing the question of where people get their distinctive

microbial mixes: Why, for instance, are the communities in the mouth

different from those in the esophagus, which in turn are different

from those in the stomach or gut?

Other labs are investigating bacteria of the esophagus, vagina, skin

and even earwax.

http://www.theage.com.au/news/world/gut-feeling-mysterious/

2006/01/23/1137864815741.html