Belly button bacteria under the microscope

Nov 08, 2012 by Matt Shipman
Ever wonder what’s living in there?

(Phys.org)—Researchers have discovered which bacteria species are most commonly found in our bellybuttons, but have still not discovered what governs which species will be found on which people. These are the first published findings of the Belly Button Biodiversity project led by NC State's Dr. Rob Dunn.

The researchers swabbed the belly buttons of 66 study participants, and then processed the samples using high-throughput genetic sequencing to identify each of the phylotypes present in a sample and how prevalent each phylotype was. For the purposes of this study, a phylotype was defined as an organism whose sequence in the 16s rDNA gene (essentially the microbial fingerprint gene) varied from other by at least three percent.

The researchers found thousands of phylotypes, but only a handful were found on a significant number of people. The vast majority of phylotypes were only found once or twice. Images of some of the phylotypes are available here.

Specifically, the study identified 2,368 different phylotypes – including, for the first time, three phylotypes of – but only eight phylotypes were found on at least 70 percent of the study participants. And those eight phylotypes were also among the most abundant – meaning that when they were present, there were a LOT of them. In fact, those eight phylotypes accounted for almost 50 percent of the total abundance of in the samples.

Some of the most common taxa found in the study belong to the genus Micrococcus, part of the Actinobacteria group of bacteria. Click to enlarge. Credit: Belly Button Biodiversity

"The common, are from a relatively small number of evolutionary lines, indicating that they have evolved traits that make them at home on ," says Dunn, who is co-author of a paper describing the work. "However, we are still trying to figure out what determines which of these species are found in a given person's . We've looked at sex, age, and a number of other factors – none of them are predictive of which species live in that person."

The researchers launched this project, in large part, because it has become increasingly clear in recent years that the collection of organisms on our skin forms our first line of defense against pathogens.

"We know that without these microbes our immune systems won't function properly," Dunn says. "In fact, this collection of microbes must have a certain composition – must form a certain microbial ecosystem – in order for our immune system to function properly. This work is a significant step toward helping us understand which are the most important players in those ecosystems."

Researchers chose to sample the belly button for two reasons. First, it is a representative site on the body that is not disturbed very often. Second, the research team wanted to engage the public in science – "and the belly button is inherently ridiculous," Dunn says. "It gets people's attention."

Altogether, the researchers found that the average belly button among study participants contains 67 different phylotypes of bacteria. And many of those bacteria were quite unexpected – including some normally found only in marine environments or in foreign soils.

The paper, "A Jungle in There: Bacteria in Belly Buttons are Highly Diverse, but Predictable," is published online in PLOS-ONE.

Explore further: How do our muscles work? Scientists reveal important new insights into muscle protein

More information: dx.plos.org/10.1371/journal.pone.0047712

Related Stories

Bacterial phylotype alterations in irritable bowel syndrome

Jan 15, 2010

Irritable bowel syndrome (IBS) is a common gastrointestinal functional disorder that can greatly affect the patient's well being. Multiple interacting mechanisms, including alterations in the intestinal microbiota, are suspected ...

Scientists find a new species of fungus -- in a wasp nest

Nov 09, 2011

While some researchers look for new species in such exotic places as the deep sea, tropical regions, or extreme environments, a team headed by Tufts researchers turned their attention towards nests of an invasive ...

For our guts, not just any microbiome will do

Jun 21, 2012

Gut bacteria's key role in immunity is tuned to the host species, researchers have found, suggesting that the superabundant microbes lining our digestive tract evolved with us—a tantalizing clue in the mysterious recent ...

Recommended for you

Genomes of malaria-carrying mosquitoes sequenced

8 hours ago

Nora Besansky, O'Hara Professor of Biological Sciences at the University of Notre Dame and a member of the University's Eck Institute for Global Health, has led an international team of scientists in sequencing ...

How calcium regulates mitochondrial carrier proteins

Nov 26, 2014

Mitochondrial carriers are a family of proteins that play the key role of transporting a chemically diverse range of molecules across the inner mitochondrial membrane. Mitochondrial aspartate/glutamate carriers are part of ...

Team conducts unprecedented analysis of microbial ecosystem

Nov 26, 2014

An international team of scientists from the Translational Genomics Research Institute (TGen) and The Luxembourg Centre for Systems Biomedicine (LCSB) have completed a first-of-its-kind microbial analysis of a biological ...

Students create microbe to weaken superbug

Nov 25, 2014

A team of undergraduate students from the University of Waterloo have designed a synthetic organism that may one day help doctors treat MRSA, an antibiotic-resistant superbug.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Egleton
not rated yet Nov 09, 2012
Just what we need. More navel gazing.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.