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The Bacterial Cloud We All Carry Could Be As Unique As A Fingerprint


All of us, no matter how together we are, are walking around in a fog - or rather, a cloud formed by millions of microorganisms spewing from our bodies. That's the conclusion of a recent study and the subject of a story from NPR's Rob Stein. It was so popular when it originally broadcast, that we're airing it again.


ROB STEIN, BYLINE: A lot of people probably know this character from the cartoon "Peanuts."


CIARA BRAVO: (As Patty) Pigpen, you're a disgrace.

STEIN: Pigpen's the little kid who walks around in a cloud of dirt, whose friends, like Violet, are always giving him grief.


SHANE BAUMEL: (As Pigpen) What's the matter?

BLESST BOWDEN: (As Violet) What's the matter, he asks. You're a mess when you eat, a mess when you play and a mess when you're just standing still.

JAMES MEADOW: Yeah, it turns out that that kid is all of us.

STEIN: James Meadow led the new research at the University of Oregon.

MEADOW: It's just a microscopic, invisible cloud that's really hard to see.

STEIN: Because our clouds aren't dirt, they're microscopic bacteria and other organisms. You see, we all carry around millions of microorganisms - bacteria, fungi, viruses. Most of them aren't dangerous. In fact, they help us in lots of ways. Scientists call this our microbiome.

MEADOW: A lot of recent work on the human microbiome has revealed that we're kind of spilling our microbiome all over our houses and our offices and the people around us.

STEIN: By touching them, sharing objects, beds. But Meadow and his colleagues wanted to see if we're also spewing our microbial companions into the air around us. So they studied the air around 11 volunteers as they sat alone, one by one, in a special sealed booth for four hours.

MEADOW: And the results really surprised us.

STEIN: Not only could they clearly detect plumes containing thousands of different types of bacteria, they could tell all sorts of things from the clouds, like whether they came from a man or a woman. And they realized each person's cloud is sort of like a fingerprint.

MEADOW: We each give off a slightly different cocktail of those bacteria. There's just really subtle differences, and you can tell that different people give off a slightly different cocktail. We could actually tell people apart.

STEIN: Meadow says this raises all kinds of possibilities, like someday maybe being able to identify a murder suspect by reading the microbial cloud he or she left behind at the scene of a crime.

MEADOW: You know, there's a lot of reasons why we might want to know if some nefarious character's been in the certain room in the last few hours, and maybe there's a way to use microbes for that.

STEIN: Other scientists agree. Rob Knight studies the microbiome at the University of California, San Diego.

ROB KNIGHT: What's exciting about this is, in addition to showing that we leave microbes behind on surfaces we touch, this also shows that we release our personal microbes into the air of the spaces that we inhabit.

STEIN: The research could also explain how we get our microbes in the first place.

KNIGHT: We know that if you live with people, and even if you just work with people, your microbial community has come to resemble theirs. And in the past, we mostly thought that that was due to touch. It may be just that you're releasing microbes into the air and some of those microbes are colonizing the people you're with.

STEIN: Knight thinks we've just begun to understand what our microbes could tell us.

KNIGHT: We're finding out that our microbes have a tremendous amount of data in them, right? And if you think about that as a data recording device that we're just beginning to read out now, your microbes may contain a tremendous amount of information about where you've been, who you've been in contact with and so forth.

STEIN: So Pigpen may not have been so far off after all.


BAUMEL: (As Pigpen) Sort of makes you want to treat me with more respect, doesn't it?

STEIN: Rob Stein, NPR News.


UNIDENTIFIED ACTORS: (As characters, singing) When you're doing the Pigpen Hoedown, you've got to have a caller you can trust because when Pigpen does the hoedown, he really kicks up some dust.


GINI HOLTZMAN: (As Peppermint Patty) Hey Chuck, we're all bumping into each other. Let me give it a try.

(Singing) Bow to your left, bow to your right, and if you find no one in sight, just bow to your toes and bow to your knees and gather 'round just as you please.

UNIDENTIFIED ACTORS: (As characters, singing) When you're doing the Pigpen Hoedown... Transcript provided by NPR, Copyright NPR.

Rob Stein is a correspondent and senior editor on NPR's science desk.