The International Space Station is swarming with bacteria

You might not immediately find yourself comparing the International Space Station with your lounge room, but it turns out that the triumph of cutting-edge engineering and international goodwill has a lot in common with the place you eat chips and fall asleep – at a microbiological level, at least. 

It’s well known that we humans carry a rich ecology with us – there are billions of microbes swarming all over you right this second – but the way microbes are transferred into the places we live and work is proving a rich area of study.

The latest habitat to come under scrutiny, as described in a paper in the journal PeerJ, is the ISS. What the researchers found on the orbiting laboratory was rich and diverse microbial community, similar to the microbiology of a private home. 

Project MERCCURI (Microbial Ecology Research Combining Citizen and University Researchers on ISS) collected samples from 15 locations on the ISS. When analysing the samples back on Earth, microbiologists at the University of California, Davis, found thousands of different species which they then compared their results to those of the Wildlife In Our Homes study, which mapped the microbial life both in private houses and public buildings (which had been been a separate Project MERCCURI project), and finally from data from the Human Microbiome Project. 

The result? The ISS data most closely resembled the variety of microbial life found in homes, where much of the microbiology was courtesy of the limited number of humans in the space. 

One of the paper’s authors, David Coil, explained that “We are completely surrounded by mostly harmless microbes on Earth, and we see a broadly similar microbial community on the ISS. So it is probably no more or less gross than your living room.”

“We were also pleased to see is that the diversity was fairly high, indicating that it did not look like a ‘sick’ microbial community,” said the paper’s lead author Jenna Lang. 

The data is not merely the work of idle curiosity either. When planning extra-planetary travel, it’s important to know what the likely biological payload of any potential craft is likely to be. The ISS, where the only microbiological travellers are brought aboard by its inhabitants and its cargo, offers a uniquely sterile testing ground that no terrestrial building could hope to match.

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