Fair warning to germaphobes: This story might cause spontaneous itchiness or an immediate desire for hand sanitizer. Still with us? Read on, brave soul.
Human skin and hair are the preferred habitat for hordes of bacteria. There could be thousands of species camped right now on your arms and legs, nestled in your armpits and scrunched between your toes.
These are things we understand. But there is a lot we don’t. “The reality is we know incredibly little about these species,” said Rob Dunn, a North Carolina State University biologist. “It’s a kind of garden that lives on people, but we don’t know what we’re planting.”
Dunn leads a project that seeks to change the way we think about the microscopic creatures that live closer to us than our loved ones. ] He and his colleagues went searching for new species of microbes. But they didn’t have to travel to some strange, exotic rainforest or deepwater vent. ] In fact, they didn’t have to go any farther than their bellybuttons.
About 900 people have participated in the Bellybutton Biodiversity Project, swabbing their innies and outies and sending the microbes to Dunn for testing.
A presentation by his team at the Ecological Society of America’s annual meeting in August made a big splash.
Dunn’s team split each bellybutton swab in two. Half went into Petri dishes (see illustration above) to see what would grow, and the other underwent genetic analysis.
Early results have been intriguing.
“We’ve found 1,400 species of bacteria,” Dunn said. “About 600 of those species don’t match up with any species known to science.”
He said scientists tend to focus on the relatively small number of microbes that pose a health threat.
Among those are Staphylococcus epidermidis and Staphylococcus aureas, two skin microbes that can cause serious infections in patients recovering from surgeries or who had catheters or other tubes inserted into their bodies.
“Staphylococcus epidermidis is a really common inhabitant of the skin,”
Said Dr. Kurt Stevenson, an infectious-disease expert and epidemiologist at Ohio State University Medical Center.
Epidermidis can cause slow-moving infections, but aureas, which is found on 30 percent of people’s skin, is a more-aggressive threat. It’s why doctors routinely wipe skin with anti-microbial agents before injections or surgery.
There are, of course, many more germs that we don’t fear. Take Bacillus subtilis, a foot-dwelling microbe that eats the amino acids in sweat. You might not know its name, but you do know when the little buggers are doing their job. They excrete a nose-wrinkling stink.
Same with Corynebacterium xerosis, one of several denizens of the armpit that excrete the body funk we aim to tame with deodorants.
Research into all kinds of body bacteria has expanded in recent years with the increasing availability of DNA analysis.
At Ohio State, immunologist and animal physiologist Michael Bailey found that, in mice, stress can cause an imbalance in gut bacteria that activates the animals’ immune systems. The result is that white blood cells attack the bacteria (good and bad) in the same way they would go after a virus.
Bailey said Dunn’s research might find similar links between skin bacteria and the body’s ability to shrug off diseases, including skin rashes.
Dunn said he is interested in learning about whether such symbiotic relationships exist.
He said the bellybutton was a good choice because it offers some shelter for bacteria from the routine scrubbings that reduce germs on our feet, armpits and hands.
As more results come back from genetic testing, Dunn said, he hopes to learn how the population of bacteria that lives on people might vary by sex, race, age and even climate. He also hopes to learn how soap and where people live (urban versus rural) affect the bacteria that live on us.
The other notable component of the research has been the public participation and response. The bellybutton research has been labeled a “citizen science project” with a website ( http://www.wild lifeofyourbody.org ) that has had more than 55,000 hits.
The website includes images of bacteria found in participants’ samples.
There have been many willing volunteers, including about 40 scientists and staffers at the North Carolina Museum of Natural Sciences in Raleigh.
“It’s an interesting project — really cool — but it’s also really good science,” said Betsy Bennett, the museum’s director and a research subject. You can see Bennett’s bellybutton bacteria on the website.
“It’s kind of weird ...,” she said. “I would say my Petri dish was average. I had small dots and some bigger dots.”
Dunn said the project shows that you don’t have to travel to far-away exotic locales to find new species and make scientific discoveries.
“I think I had 400 to 500 species,” Dunn said about his own skin samples. “I actually had on my forehead a species that’s only known to eat pesticides.”
Of course a discovery such as that leads to yet another scientific inquiry.
“What’s it doing there?”