US, WASHINGTON (ORDO NEWS) — If we are going to travel in the universe, we need to know more about the long-term consequences of living in space. Two studies have now shown how the International Space Station (ISS) leaves a microbial “imprint” on astronauts, and vice versa.
The studies are part of ongoing projects to study how space travel affects the human microbiome – all the microorganisms that live on and inside the human body, from intestinal bacteria to the microorganisms on our skin – and how this microbiome, in turn, affects to the spaceship.
This study examined crew members who had been on the ISS for six to 12 months, and it was discovered that their microbiomes had indeed become more diverse in a relatively sterile and bacteria-free space environment.
“Since the station has an almost sterile environment, we expected a decrease in the diversity of the microbiome in space compared with the pre-flight or post-flight state, since astronauts are less exposed to environmental bacteria,” says microbiologist Hernan Lorenzi of the J. Craig Venter Institute.
This unexpected finding may be the result of carefully controlled diets aboard the ISS: NASA is working hard to ensure that more than 200 dishes and drinks are available on the space station, which probably gives astronauts a wider choice than at home.
More mixed results were obtained when testing skin microbiomes: some astronauts showed an increase in the diversity of skin bacteria, while others showed a decrease. The only persistent trend was a decrease in the number of Proteobacteria bacteria caused by the cleanliness of the space station (this type of bacteria is abundant in the soil).
And it turns out that we also cause microbial changes in the opposite direction. So much so that scientists can tell which astronauts were aboard the ISS simply by looking at the microbial traces they left.
“The station’s microbiome tended to resemble the composition of the skin microbiome of astronauts who at that time lived in space,” says Lorenzi. “The astronaut’s skin begins to influence the station’s microbiome.”
Researchers took swabs from the mouth, nose, ears, skin, and saliva from one ISS crew member before, during, and after the mission.
Then they compared them with samples taken from eight ISS surfaces during and after a member of the crew – and the researchers were able to find matching structures of microorganisms.
A special laboratory technique known as metagenomic sequencing was used to study DNA in samples in detail. Altogether, the astronaut’s microbiome comprised 55 percent of the station’s surface microbiome, and the surface microbiome closely resembled the microbes found in skin samples.
The study showed that these bacterial similarities persisted up to four months after the astronaut returned to Earth. So far, this aspect of the study has affected only one crew member, but it provides the basis for future research.
Understanding the relationship between the microbiomes of space travelers and spacecraft that seem close, scientists will be able to better plan long-term stays out of orbit and have more options for ensuring the safety and health of astronauts.
“There is an interaction between the microbial community on the space station and its crew, and understanding the details is important to prevent health or spacecraft complications during long-term human flights in space,” says molecular biologist Crystal Jane from Lawrence Livermore National University.
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