Bacteria in Space: International Space Station Has Lots of The Same Microbes as Any Other Home

Just like any other place where humans have spent decades eating, the International Space Station is full of bacteria. NASA

Any given adult human body is full of trillions of invisibly tiny lodgers keeping us company, helping us survive—and, yes, occasionally giving us a sniffle or a stomachache. Those microbes also end up making their homes everywhere we go, including our houses, offices and subway cars. And now a new study published in the journal PeerJ looked at the most exotic house humans have built, the International Space Station, and found that it, too, is full of tiny bacterial roommates—12,554 different species of bacterial roommates, in fact. But in general, they're nice, mundane bacterial roommates.

"'Is it gross?' and 'will you see microbes from space?' are probably the two most common questions we get about this work," co-author David Coil, a microbiologist at the University of California, Davis, said in a press release. "It is probably no more or less gross than your living room."

To do the analysis, the team enlisted Japanese astronaut Koichi Wakata, in space during 2014, to swab 15 surfaces in the space station—things like telephones, computer keyboards and air vents—and sent those samples down to Earth for processing.

Then, they compared them to a similar group of samples gathered from homes here on Earth—cutting boards, toilet seats, pillowcase, door trim—as well as from bacterial samples taken from human bodies, to see whether the space station's microbes more closely match a home or a body.

If those terrestrial samples don't quite seem like they match the mundanity of the space station samples, there's a reason for that: the space kitchen is located in the Russian part of the station, which the scientists weren't given permission to sample, and according to the paper, "swabbing the toilet seat was deemed inappropriate due to biosafety concerns."

Read more: NASA Put Dangerous Bacteria on a Satellite to Find Treatments for Future Space Travelers

The most common bacteria in space were all the sorts of critters scientists expect to find where humans go, although their technique couldn't distinguish between living and dead microbes. But what the space station was missing that homes here on Earth have is bacteria associated with the outdoors and pets. That's not surprising, since the oldest part of the International Space Station went into orbit in 1998 and astronauts are kept in quarantine just before they launch.

While the study may feel a little light-hearted, its results could be important for helping NASA and other space agencies keep humans healthier in space for longer periods of time as they look to leave the low-Earth orbit of the space station.