This bacteria survived outside the space station for a whole year

A year in space is not a walk in the park. Just ask Scott Kelly, the American astronaut who spent a year on the International Space Station (ISS) in 2015.

His long stay in space changed his DNA, telomeres and gut microbiome, he lost bone density, and his feet were still sore three months later.

But it is quite another thing to survive in bare space outside of the shielding of the ISS, where UV rays, vacuum, huge temperature fluctuations, and microgravity are looming threats.

It is therefore quite an achievement that a species of bacteria found for the first time in a box of meat, Deinococcus radiodurans, was still alive after a year of living on a specially designed platform outside of the ISS pressurized module.

Researchers have been studying these powerful microbes for some time; In 2015, an international team set up the Tanpopo mission outside the Japanese Kibo experimental module, to test resistant bacterial species.

Now D. radiodurans passed with flying colors.

The bacterial cells were dehydrated, shipped to the ISS and placed in the exposed facility, a platform constantly exposed to the space environment; in this case, the cells were behind a glass window that blocked UV light at wavelengths less than 190 nanometers.

“The results presented in this study may increase awareness regarding planetary protection issues, for example on the Martian atmosphere which absorbs UV radiation below 190-200nm,” the team from Austria wrote, from Japan and Germany in their new document.

“To mimic this condition, our experimental facility on the ISS included a window made of silicon dioxide glass.”

It’s not the longest time D. radiodurans was kept under these conditions – in August we wrote about a sample of the bacteria left up there for three whole years.

But the team weren’t trying to win a world record, but instead trying to find out what makes D. radiodurans so good at surviving in these extreme conditions.

SEM images of D. radiodurans command (left), and after the LEO exposure (right). (Ott et al., Microbiome, 2020)

So, after a year of radiation, freezing and boiling temperatures, and without gravity, the researchers brought the space bacteria back to Earth, rehydrating both a witness who had spent the year on Earth and the sample from low Earth orbit (LEO), and compared their results.

The survival rate was much lower for the LEO bacteria compared to the control version, but the bacteria that survived appeared to be doing well, even though they had become a little different from their Earth-bound brethren.

The team found that LEO bacteria were covered with small bumps or vesicles on the surface, that a number of repair mechanisms had been triggered, and that certain proteins and mRNAs had become more abundant.

The team isn’t sure exactly why the vesicles (which you can see in the image above) formed, but they have a few ideas.

“The intensified blistering after recovery from LEO exposure can serve as a rapid response to stress, increasing cell survival by removing stress products,” the team wrote.

“Additionally, the outer membrane vesicles may contain proteins important for nutrient acquisition, DNA transfer, toxin transport and quorum sensing molecules, causing the activation of resistance mechanisms after space exhibition. “

This type of study helps us understand whether bacteria might survive other worlds, and perhaps even the journey between them, which will become more and more important as we humans and the germs we bring with us, let’s begin to travel beyond our Moon in the solar system. , and one day maybe even beyond.

“This research helps us understand the mechanisms and processes by which life can exist beyond Earth, expanding our knowledge of how to survive and adapt in the harsh environment of outer space.” , said University of Vienna biochemist Tetyana Milojevic.

“The results suggest that the survival of D. radiodurans in LEO for a longer period is possible due to its efficient molecular response system and indicates that even longer and farther trips are achievable for organisms with such capabilities. “

The research was published in Microbiome.