Near the end of 2017, astronauts aboard the International Space Station (ISS) discovered a set of microbes on a satellite module which were believed to be of alien origin, and they sequenced those microbes in the beginning of 2018. Now a new study from Northwestern University suggests the bacteria floating above Earth is evolving to survive conditions in space. However, the harsh conditions have so far not caused the bacteria to mutate into antibiotic-resistant strains, as was previously believed.
The team published the results of their study in the journal mSystems. They learned that the bacteria they found on the surface of the ISS module had different genes than their cousins on Earth. However, the bacteria floating above Earth is not believed to be threatening to human health. Scientists just think they are responding in a way which is causing them to evolve to survive their stressful environment.
“There has been a lot of speculation about radiation, microgravity and the lack of ventilation and how that might affect living organisms, including bacteria,” lead researcher Erica Hartmann of Northwestern said in a statement. “These are stressful, harsh conditions. Does the environment select for superbugs because they have an advantage? The answer appears to be ‘no.’”
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Given that plans to send astronauts to Mars are becoming more realistic and serious, scientists have become especially interested in learning about the behavior of microbes in enclosed areas.
“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.”
Scientists have found thousands of microbes on the ISS, most of which traveled to space with astronauts or cargo transported to the space station.
“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.”
Bacteria uses their genes to adapt to live on different types of surfaces, or they mutate. The bacteria floating above Earth used their genes to respond to stress in order to eat, grow and live in the difficult conditions of space.
“Based on genomic analysis, it looks like bacteria are adapting to live—not evolving to cause disease,” said Ryan Blaustein, a postdoctoral fellow in Hartmann’s laboratory. “We didn’t see anything special about antibiotic resistance or virulence in the space station’s bacteria.”
Even though knowing that the mutated bacteria won’t threaten astronauts or potential space tourists, the study’s authors are concerned about unhealthy people who could still spread their disease aboard space stations or space shuttles.
“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.