One year in space is no walk in the park. Just ask Scott Kelly, the American astronaut spent a year on the International Space Station (ISS) in 2015.
His long stay in space changed his DNA, telomeres and gut microbiota, he lost bone density and three months later he still had leg pain.
But a whole different thing is that there exists in the bare space outside of ISS protection, where UV radiation, vacuum, massive temperature fluctuations and microgravity are all imminent threats.
So it’s a feat when a bacterium is first found in a can of meat, Deinococcus radiodurans, still alive and well after a year of living on a specially designed platform outside the ISS pressurization module.
Researchers have been investigating these powerful bacteria for a while; in 2015, an international group formed the Tanpopo mission outside of the Kibo Japanese Experimental Module, to put tough species of bacteria to the test.
Now, D. radiodurans Gone with flying colors.
Bacterial cells are dehydrated, transported to the ISS, and placed in the Exposure Facility, a platform continuously exposed to the spatial environment; in this case, the cells are behind a glass window that blocks UV rays at wavelengths lower than 190 nanometers.
“The results presented in this study may raise awareness of planetary protection concerns; for example, the Martian atmosphere absorbs UV radiation below 190-200 nm,” the team from Austria , Japanese and German write in their new article.
“To mimic this condition, our test set-up on the ISS included a silicon dioxide glass window.”
This is not the longest time D. radiodurans was kept under these conditions – in August, we wrote about a bacterium that was left on it for three years.
But the team wasn’t trying to hit the world record, instead they’re trying to discover what makes D. radiodurans only very good at surviving these extreme conditions.
So, after a year of radiation, freezing and boiling temperatures and no gravity, the researchers brought the astronaut bacteria back to Earth, rehydrating the already spent control device. year on Earth and Low Earth Orbit (LEO) sample, and compare their results.
The survival rate of the LEO bacteria is much lower than the control version, but the bacteria that survive seem to be fine, even though they vary slightly from their Earth-based siblings.
The team found that the LEO bacteria were covered with tiny bumps or blisters on the surface, some repair mechanisms were activated, and some proteins and mRNAs became richer.
The team isn’t sure exactly why blisters (you can see in the image above) form, but they have a few ideas.
“Enhanced blisters after recovering from LEO exposure may act as a rapid stress response, enhancing cell viability by eliminating the product,” the team wrote. stress products.
“In addition, the outer pockets of the outer membrane may contain proteins important for nutrient acquisition, DNA transfer, toxin transport and delegate-inducing molecules, and stimulate the activation of post-transition resistance mechanisms. contact with space. “
This kind of research helps us understand whether bacteria can exist in other worlds, and maybe even the journey between them, which will become more and more important as we humans and microbes. The worm we bring with it begins to travel further from our Moon into the Solar System, and possibly even further.
Biochemist Tetyana Milojevic of the University of Vienna said: “These investigations help us understand the mechanisms and processes by which life can exist outside of Earth, expanding our knowledge of how to exist and adapt in the hostile environment of space “.
“The results show the existence of D. radiodurans in LEO a longer time is possible due to its efficient molecular response system and indicates that longer, longer journeys are possible for organisms with such capabilities. “
Research has been published in Microbiota.