A year in space is not a walk in the park. Ask Scott Kelly, an American astronaut who spent a year on the International Space Station (ISS) in 2015.
His long stay in space altered his DNA, telometry and gut microbiome, he lost bone density, and three months later, his legs were still sore.
But it’s a completely different matter to survive in outer space outside the protection of the ISS, where UV radiation, vacuum, huge temperature fluctuations and microgravity are all inevitable death.
Thus, it is a real feat that the species of bacteria, Deinococcus radiodurans, survived and continued to live after a year on a specially designed platform outside the sealed ISS module.
Researchers have studied powerful microbes for some time; Back in 2015, an international team organized a mission outside of the Japanese experimental module to test hardy bacteria.
Radiodurans passed the test successfully.
The bacterial cells were dehydrated, sent to the ISS and placed in an open object – a platform constantly exposed to the space environment; the cells were placed behind a glass window that blocked UV light with wavelengths less than 190 nanometers.
“The results presented in this study could raise awareness of planetary defense issues, such as the Martian atmosphere, which absorbs UV radiation below 190-200 nm,” a team from Austria, Japan and Germany wrote in a new paper.
'To simulate Martian conditions, our experimental setup on the ISS included a silicon dioxide window.'
A team of scientists was trying to figure out what makes D. radiodurans so good at surviving these extreme conditions.
So, after a year of radiation, extreme temperatures and a lack of gravity, the researchers brought space bacteria back to Earth, rehydrated both the control sample that spent a year on Earth and the sample from low Earth orbit.
The bacteria that survived from space was much lower compared to the control version, but the bacteria that survived seemed to be fine, but they were slightly different from their terrestrial counterparts.
The team found that the bacteria were covered with small bumps or bubbles on the surface, a number of repair mechanisms were triggered, and some proteins and mRNA became larger.
(Ott et al., Microbiome, 2020).
Scientists don't fully understand why the bubbles formed (which you can see in the picture above), but they have a few ideas.
“Enhanced vesiculation after recovery from outer space can serve as a rapid response to stress, which increases cell survival by removing stress products,” the team wrote.
“In addition, the outer membrane vesicles may contain proteins important for nutrient production, DNA transport, transport of toxins and molecules, triggering the activation of resistance mechanisms after exposure to outer space.”
Such research helps us understand whether bacteria can survive in other worlds, and even travel between them.
'The results suggest that the survival of D. radiodurans in orbit for a longer period is possible due to its efficient molecular response system, and indicate that even longer journeys are possible for organisms with such capabilities.'
Research published in Microbiome.
Sources: Photo: (Tetyana Milojevic)
