Certain bacteria can clump up, survive harsh conditions of space for many years, study suggests

Scientists from Japan have discovered that there are certain types of bacteria that can survive the harsh conditions of outer space.The study found that a species of bacteria highly resistant to radiation and other environmental hazards managed to survive outside the International Space Station for three years. The results of the study were published in the journal Frontiers in Microbiology.The Japanese Tanpopo mission, of which the study is a part, is an orbital astrobiology experiment looking into the potential for interplanetary transfer of life, organic compounds, and possible terrestrial particles in low-Earth orbit. The mission was undertaken to test the 'panspermia' theory which suggests that microbes can pass from one planet to another and distribute life.Under the Tanpopo mission umbrella, researchers also included pellets of dried Deinococcus bacteria – a bacterium known to be extremely hardy and resistant to nuclear radiation on Earth – in aluminium plates placed on panels outside the space station that are exposed to space non-stop but also space radiation.Study author Akihiko Yamagishi and his team used an aircraft and scientific balloons to find Deinococcus bacteria that was actually floating 400 km above Earth's surface in 2018. This led Yamagashi to wonder if the bacteria could survive in space and even the journey to other planets during extreme temperature fluctuations and harsh radiation conditions.[caption id="attachment_8771931" align="alignnone" width="1280"]

Deinococcus radiodurans. Image Credit: Micropia[/caption]For the mission, researchers prepared samples of the bacteria in pellets of various thicknesses and placed them in wells of aluminium plates, collecting data after one, two and three years. The bacteria were then tested to see how they fared.Study authors found that bacteria that were larger than 0.5 millimetres were able to survive partially, sustaining DNA damage. They saw that although bacteria on the surface of the colony died, a protective layer beneath it survived. As per study authors, collectively the results support the possibility of "microbial cell aggregates (pellets) as an ark for interplanetary transfer of microbes within several years."However, Deinococcus bacteria studied inside the space station did not fare so well – moisture and oxygen proved harmful to its survival.According to researchers, cell pellets with a thickness greater than 0.5 mm are expected to survive between 15 and 45 years of exposure to UV on ISS EF and 48 years exposure to space in the dark.As per researchers, "Deinococcal cell pellets in the sub-millimeter range would be sufficient to allow survival during an interplanetary journey from Earth to Mars or Mars to Earth."