ISS Astronauts Left With Microbial ‘Fingerprints’ During and After Stay in Space

Because space agencies all over the world plan to make it further into the Universe, a couple of studies have been carried out on the long-term effects of living in space. Two new research has unveiled the way the International Space Station (ISS) leaves a microbial mark on astronauts, and vice versa.

These studies are part of ongoing projects that examine the way space travel affects the human microbiome, which are all the microorganisms that live on and inside the human body, from gut bacteria to microorganisms on our skin. The studies also analyze how that microbiome then impacts the spacecraft around astronauts.

Increased Gut Bacteria

The first research was an analysis of nine astronauts, published in the journal Scientific Reports in 2019. It examined crew members that lived on the ISS between six and 12 months and found that their gut microbiomes actually became more varied in the sterile and bacteria-free conditions of space.

“Since the station is a very clean environment, we were expecting reduced gut diversity in space compared to preflight or postflight because the astronauts are less exposed to environmental bacteria,” said microbiologist Hernan Lorenzi, from the J. Craig Venter Institute.

This surprising discovery might be an outcome of the carefully managed diets the astronauts have onboard the space station. NASA offers them more than 200 food and drink options, probably giving astronauts a more broad choice than they would have at home.

This ‘fingerprinting’ of the gut microbiome could, in fact, be positive because, in general, the more varied our gut bacteria is, the better our chances of preventing diseases. More mixed results were found when they analyzed skin microbiomes, as some astronauts had an enhance in the variety of their skin bacteria, while others had a decrease.

A microbiome swab kit on the ISS. [Image: NASA]
The research also found that there have also been changes in microbes in the opposite direction. In fact, the changes were so intense that scientists are able to tell which astronauts have lived on the ISS only by looking at the microbial traces they have left behind.

“The station microbiome tended to resemble the composition of the skin microbiome of the astronauts that were living in space at that particular moment,” Lorenzi explained. “Astronaut skin starts to affect the microbiome of the station, even as the station affects the skin of the astronauts.”

Astronaut’s Microbiome Left on the ISS

That is where the second research, published recently in PLOS One, comes into the picture. Scientists gathered mouth, nose, ear, skin, and saliva swabs from an ISS crew member before, during, and after their mission. These swabs were then compared with samples collected from eight ISS surfaces during and after the astronaut’s stay; the researchers found matching patterns of microorganisms.

A particular lab technique called shotgun metagenomic sequencing was used to analyze the DNA in the samples back on Earth. Overall, the crew member’s microbiome was found in 55 percent of the surface microbiome, and the surface microbes resembled the ones found in the skin samples.

These bacterial analogies even stayed for up to four months in the ISS after the crew member left, according to the research. While this study only involved one astronaut, it offers a fascinating basis for future research.

By learning about the correlation between the microbiomes of space travelers and the vehicle they stay in, scientists will be able to plan better long stays out of orbit and will be more equipped to keep astronauts healthy.

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