The environment in outer space is extremely hazardous to most life. Once in space, objects are battered with cosmic radiation, solar UV radiation, extreme vacuum, and significant temperature fluctuations. It sounds like an environment where nothing alive could survive without complex protective systems such as those used by astronauts. Despite the extreme environment, a bacteria called Deinococcus radiodurans was recently recovered after spending a year in low Earth orbit outside the International Space Station.
An international team assembled around the Space Biochemistry group at the University of Vienna has investigated how the microbes could survive the transfer from one celestial body to another. The study will give a deeper understanding of the molecular mechanisms behind microbial survivability in outer space. An extremophile’s ability to migrate between planets, distributing life across the universe is the foundation for the panspermia hypothesis, the interplanetary transfer of life.
The study has investigated the influence outer space had on the microbe on a molecular level. After spending a year outside the ISS during the Tanpopo Space Mission, researchers found that the bacterium had no morphological damage and produced numerous outer membrane vesicles. Vesicles are a multifaceted genomic and protein response initiated in response to cell stress.
Vesicles help the bacteria to repair DNA damage and defend against reactive oxygen species. Researchers also found that processes inside the bacterium impacting transport and energy status were altered in response to space exposure. The bacterium used a stress molecule called polyamine putrescine as a reactive oxygen species scavenger to regenerate from space exposure.
Lead researcher Tetyana Milojevic said the investigation helps researchers understand the mechanisms and processes that can allow life to exist beyond Earth. The research also helps expand our knowledge of surviving and adapting in outer space. Researchers believe the bacterium could have survived low Earth orbit for even longer.