The International Space Station may need more microbes to keep astronauts healthy

by ALLISON PARSHALL

The overly sterile environment of the International Space Station is missing important microbes, a new detailed map shows. If we want to live off Earth, we may need to take more of our bacterial friends with us

For almost a quarter-century, humans have continuously occupied what is arguably our most isolated habitat ever: the International Space Station, or ISS. Perched in the near vacuum of low-Earth orbit, it’s been home to some 270 people and a variety of animal guests—plus the microbes that hitched a ride to space on the bodies of those residents.

There these uninvited microbial guests have been evolving. Bacteria adapt to cosmic radiation with new ways to repair their DNA. Some become resistant to antibiotics and sterilizing agents or develop other changes that make them more likely to cause disease.

“This is such an extreme environment,” says Rodolfo Salido, a bioengineer at the University of California, San Diego. And the microbes that inhabit it can directly affect astronaut health. To map the space station’s microbial world, Salido and his colleagues sent swabs up to space, where astronauts sampled hundreds of surfaces. Their resulting three-dimensional map of the ISS’s microbial diversity, published on Thursday in the journal Cell, shows that this orbital habitat lacks many types of bacterial life that humans normally encounter and that may be important for our well-being. To stay healthy on future long-term off-world forays, the researchers suggest, we may need a little more help from our microbial friends.

“To take care of us humans, we have to take care of our human microbes. And that’s going to be a very interesting challenge” in space travel, says Martin Blaser, a microbiologist at Rutgers University, who was not involved in the new study.

In December 2020 Salido and his colleagues collaborated with NASA’s Jet Propulsion Laboratory to launch about 1,000 sterilized sampling devices to the ISS. The team had redesigned the devices to work in space: as an Earth-bound scientist, Salido had learned a lot from a visit to a replica of the ISS in Houston, where astronaut Michael Barratt pointed out that the researchers’ normal sampling swabs were far too large and flammable to fly.

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