Genetic evidence has shown that, despite their seemingly adverse conditions, bacteria at the International Space Station (ISS) are adapting to survive, not becoming dangerous, antibiotic-resistant superbugs, the researchers said.
The ISS is home to thousands of different microbes that have traveled to space, whether astronauts or freighters.
With many space agencies preparing to send travelers to Mars, there has been a growing interest in understanding how these microbes would behave indoors.
The team, from Northwestern University in the United States, found that the bacteria isolated from ISS contained genes different from their counterparts on Earth.
These genes did not make the bacteria more harmful to human health.
the bacteria are simply responding, and perhaps evolving, to survive in a stressful environment.
"There has been a lot of speculation about radiation, microgravity and lack of ventilation and how this can affect living organisms, including bacteria," said lead author Erica Hartmann, an assistant professor at the institute.
"People will be in small capsules, where they will not be able to open windows, leave or circulate the air for long periods of time.
"These are stressful and difficult conditions. We are genuinely concerned about how this can affect microbes," Hartmann said in the study published in the journal mSystems.
The team compared strains of Staphylococcus aureus – which contains the treatment-resistant MRSA strain; and Bacillus cereus – which lives on the ground and has fewer implications for human health – on the ISS for those on Earth.
"Based on genomic analysis, it appears that bacteria are adapting to live, not evolving to cause disease," said Ryan Blaustein, a postdoctoral student at the college.
"We did not see anything special about antibiotic resistance or virulence in the bacteria of the space station," added Blaustein.
While this is good news for astronauts and potential space tourists, Hartmann and Blaustein have pointed out that sick people can still spread diseases in space stations and space shuttles.