Bacteria On Our Bodies

How much bacteria do people carry around?

Enough to fill a big soup can. "That's three to five pounds of bacteria," says Lita Proctor, the program coordinator of the National Institutes of Health's Human Microbiome Project, which studies the communities of bacteria living on and in us. The bacteria cells in our body outnumber human cells 10 to 1, she says, but because they are much smaller than human cells, they account for only about 1 to 2 percent of our body mass—though they do make up about half of our body's waste. 

The host of bacteria we carry around weren't well-cataloged until recently. In July 2011, at North Carolina State University, the Belly Button Biodiversity study found about 1,400 different strains of bacteria living in the navels of 95 participants. Of these, 662 strains were previously unrecognized.
A new non-profit called My Microbes wants to connect people through a social network exclusively to talk and compare experiences with, you guessed it, bacteria (specifically gastrointestinal bacteria). 


Hundreds of different kinds of bacteria, viruses, yeast, fungi, and other micro-organisms. Forsyth scientists, most of whom are on the faculty of the Harvard School of Dental Medicine, have found 615 different species of bacteria - and they're still counting. 

It's a great place for micropests to dwell. Glistening white plateaus, dark crevices, and slimy surfaces boast steamy temperatures of 95 degrees Fahrenheit. The microbes bathe in a saliva-induced humidity of 100 percent, and eat a lavish diet of sugar and other carbohydrates. It's so lush and varied, Mager refers to it as a mini-jungle. 

"In one mouth, the number of bacteria can easily exceed the number of people who live on Earth (more than 6 billion)," notes Sigmund Socransky, associate clinical professor of periodontology at Harvard. "These bugs don't colonize your mouth in a random way; rather, they form communities in a pattern that is dictated both by other bugs and by the environment. Bacteria affect their environment, and the environment affects them. Although they touch each other, the floor of the mouth is populated by different communities than the bottom of the tongue, and the top of the tongue hosts a biota unlike that on the roof of your mouth." 

Years of detecting and identifying mouth tenants have revealed that those living in healthy mouths can be remarkably different from those living in diseased mouths. Some bacteria increase in number, while others decrease.