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What's in Your Belly Button?

Some scientists want to explore the black expanse of space or uncover secrets buried on the floor of the deepest seas. Biologist Rob Dunn wants to know what's in your belly button.

Actually, Dunn and his team at North Carolina State University want to know what's in a lot of belly buttons. They have taken 340 samples so far and hope to get many thousands more before completing the Belly Button Biodiversity Project.

Would you do it? Participants answer a questionnaire: Are you a boy or girl? Are you an inny or outie? Do you wash your b.b. with soap or not? Then you provide a sample by swiping your belly button with a long cotton swab.

Bacteria Live in Belly Buttons

A sample of what? The cotton swab picks up some of the bacteria and other microorganisms living in your belly button. Yes, microorganisms live on your skin, even though you can't see them. After it takes a tour of your belly button, the swab gets wiped on a specially prepared dish, where the bacteria can grow. Then the researchers figure out what's growing on you.

microscopic photograph of Enterococcus mundti

So far, the most common colonies are from Staphylococcus epidermidis and Micrococcus luteus. Have they found any rare, truly bizarre bacteria? Why, yes — in Dunn's own belly button. It's a bacterium called Enterococcus mundti and it was only recently discovered by scientists. "(It's) found on me, soybeans, and silk moths. Go figure," Dunn said.

It's a tricky thing using those special plates — called agar plates — to grow bacteria. Some bacteria grow like crazy on the plates, so we know the most about those kinds, Dunn said.

Plenty of bacteria remain undiscovered. And we don't know much about many of the bacteria that live on our bodies because we can't grow them.

Dunn and his team are extracting bacterial genetic information from the belly buttons, and by literally reading it, they know which species of bacteria live on the skin. "When it is done, we will undoubtedly find some very rare species, some of them probably new to science," Dunn said.

Bad Germs, Good Germs?

Bacteria are the most common micro-critters living on our skin, but Dunn says there are also fungi, yeast, and mites. But don't be alarmed. He doesn't even like to call them germs because that makes them sound bad.

Most microscopic creatures that live on your skin — including those in the belly button — won't hurt you or make you sick. "The vast majority (99.99%) of the bacteria on your body are not bad," Dunn said.

Some even help keep us well. That's why we shouldn't misuse antibacterial soap and bacteria-killing medicines called antibiotics, he said. "Killing the species that live on and in you can make you sicker, rather than more healthy, if you kill the wrong ones."

The team is studying one type of belly button bacteria that seems to be producing antibiotics. That means one bacterium is producing chemicals that kill other bacteria. Watch out, bad bacteria!

Early Results Reveal Few Outies

Of the 340 people in the belly button study, just 4%, or about 13 people, were outies. That means their belly buttons stick out a little bit. Innies, on the other hand, go in like a teeny tiny swimming pool — perfect places for germs to hide out and grow.

Most people say they wash their belly buttons with soap, but 14% said they never do. Doctors recommend you wash your belly button with soap when you shower, just like the rest of you. Dunn says he isn't sure it's good advice, but you can be sure your mom will want you to follow your normal stay-clean routine!

Did you know that babies are germ-free until they're born? Then it's a lifelong process of acquiring all the micro-critters that hop aboard — both inside our bodies and outside on our skin. So far, the researchers have collected samples from 119 people younger than 20, including 25 who were younger than 5. Early results show the kinds of bacteria in the belly buttons of older people differ from the kinds found on younger folks.

"A key question is why," Dunn said.

Author Rob Dunn Biologist

Dunn will continue to report on the belly button project and other projects, including one that has kids and grownups collect bacteria samples from their houses and backyards. He has written a book called "The Wild Life of Our Bodies."

"Our bodies are a wonderful wilderness of life," Dunn said. "It is a wilderness we are just beginning to understand and yet it is one that affects us every day. It is the last frontier right under our noses and, of course, shirts."

Reviewed by: Mary L. Gavin, MD
Date reviewed: May 2011

Kids Health

Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.

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