Are Bacteria on the ISS Dangerous?
А new study has found that bacteria stranded in the International Space Station are not mutating into dangerous microbes, as was previously feared. Instead, the bacteria are responding to their environments — perhaps simply trying to adapt to the harsh conditions in space.
The findings, published yesterday in mSystems, an open access journal published by the American Society for Microbiology, report that the bacteria on the ISS did vary genetically from their counterparts on Earth. At the same time, the genetic mutations did not make the bacteria more dangerous to humans.
“There has been a lot of speculation about radiation, microgravity and the lack of ventilation and how that might affect living organisms, including bacteria,” said assistant professor Erica Hartmann of Northwestern University who led the study. “These are stressful, harsh conditions. Does the environment select for superbugs because they have an advantage? The answer appears to be ‘no.’”
The issue of bacteria in space has become more relevant in the recent years — sending people to the moon, and then to Mars, could mean bacterial mutations onboard the spacecraft for a prolonged period of time.
“People will be in little capsules where they cannot open windows, go outside or circulate the air for long periods of time,” said Hartmann. “We’re genuinely concerned about how this could affect microbes.”
Unlike unmanned spacecraft, which can be properly sterilised, the ISS hosts thousands of microbes that have entered the station on astronauts or with cargo. Northwestern’s researchers used the data from the National Center for Biotechnology Information’s public database that contains genomic analysis of bacteria from the ISS.
In particular, Hartmann and her team compared Staphylococcus aureus and Bacillus cereus strains on the ISS with those on Earth. Staphylococcus aureus may contain the MRSA strain, which makes humans resistant to antibiotics. Bacillus cereus is generally found in soil and is much less detrimental for human health.
“Bacteria that live on skin are very happy there,” Hartmann said. “Your skin is warm and has certain oils and organic chemicals that bacteria really like. When you shed those bacteria, they find themselves living in a very different environment. A building’s surface is cold and barren, which is extremely stressful for certain bacteria.”
To survive this change, microbes undergo a natural selection, with those containing advantageous genes more likely to stay intact. Other microbes mutate to adapt to the new conditions. These changes take place so that the microbes can continue to survive and grow in their new environment, say the researchers.
“Based on genomic analysis, it looks like bacteria are adapting to live — not evolving to cause disease,” said Ryan Blaustein, lead author of the study. “We didn’t see anything special about antibiotic resistance or virulence in the space station’s bacteria.”
Space tourism is another rapidly developing industry, and the findings will have tremendous implications for those missions. Hartmann and Blaustein warn that although their findings bring good news to astronauts and potential space tourists, the conditions in space are still not perfect: people with illnesses can still spread harmful bacteria on space stations and spacecraft.
“Everywhere you go, you bring your microbes with you,” Hartmann said. “Astronauts are exceedingly healthy people. But as we talk about expanding space flight to tourists who do not necessarily meet astronaut criteria, we don’t know what will happen. We can’t say that if you put someone with an infection into a closed bubble in space that it won’t transfer to other people. It’s like when someone coughs on an airplane, and everyone gets sick.”
Photo credit: Roscosmos
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