Earth microbes survive NASA's simulated Martian conditions

February 22, 2021

Some terrestrial microbes can survive on Mars ... briefly. (Pixabay/Alexander Antropov)

In collaboration with NASA, the German Aerospace Center has discovered that some valuable microbes found on Earth — including one that's highly important for industrial and pharmaceutical purposes — can temporarily exist on Mars, a conclusion drawn from their recent experiment MARSBOx, or rather, Mars in a box, that has timely implications for space exploration.

Meant to shed light on the benefits — and dangers — of bringing microbes to Mars via human spaceflight, the agencies' study was published Monday in Frontiers in Microbiology, serendipitously close to last week's landing of the rover Perseverance. MARSBOx, which stands for “The Microbes in Atmosphere for Radiation, Survival and Biological Outcomes Experiment,” sent a box containing various microorganisms into Earth’s stratosphere, simulating the Red Planet’s extreme conditions to a tee.

Upon retrieval, the researchers confirmed that two microbes survived, one of which is the incredibly valuable fungus Aspergillus nigerIt is widely used for industrial purposes such as food preservation and waste management, and is also used in the creation of medicines.

Approximately 20 miles above Earth’s surface lies its stratosphere, which absorbs over 99% of ultraviolet radiation from the sun. Also called the ozone layer, it contains about 1,000 times the amount of radiation needed to cause a standard human sunburn. Without the layer’s protection, many living things on Earth, including humans, would die.

"Mars does not have a significant ozone layer, unlike Earth, and therefore experiences higher levels of damaging UV radiation,” Katharina Siems, an author of the paper, told The Academic Times. “Similar levels of UV radiation can be found in Earth’s stratosphere.”

After being exposed from within the Mars box, however, the advantageous species of fungus appeared to withstand such radiation, as well as the very low temperatures and exceedingly dry air that also constitute the Earth’s stratosphere.

“It was interesting to see that the spores were able to survive, temporarily, under simulated Martian conditions,” Siems said, “like radiation, temperature and desiccation.”

A. niger is already known to be highly resistant to general space radiation; a study from 2020, which shares an author with MARSBOx, saw that black mold caused by the fungus was found on the International Space Station and established that it can survive in the extreme conditions of space. But Siems, a postdoctoral student at the German Aerospace Center, was surprised that the organism could withstand the specific-to-Mars conditions in the latest research.

“Human spaceflight will inevitably involve microorganisms because they are so intertwined with us and the environment around us,” she said. “Knowing more about the resistance and physiology of microorganisms on Mars will give us more information about potential impacts, but also for biotechnological applications.”

Because of the uses that A. niger offers to society — including waste management and citric acid production, which aids in food preservation and pharmaceuticals — Siems believes that it’s promising for future colonization efforts that it can live on Mars. It also suggests other fungi could potentially survive, and their function could be redirected to benefit humans.

An example of such utility would entail using the mycelium of filamentous fungi as building blocks for structures in a Martian colony. Siems says this could keep material transportation costs as low as possible, noting that if humans manage to colonize the terrestrial planet, this could be a breakthrough for survival tactics. 

The bacteria Salinisphaera shabanensis also survived its journey in the box, although much less robustly, indicating that it or a microorganism like it may already exist on Mars. Due to its known existence on Earth in locations that could have similar counterparts on Mars, such as deep sea brines with very low temperatures, S. shabanensis offers a possible starting point for locating other Martian life — perhaps with the newly landed Perseverance.

“Honestly, we did not plan the publication with the timing of Perseverance's landing on Mars, but we are glad that with the rover landing, our study was a great fit and brings new attention to research on Mars,” Siems said.

The researchers are now working on an experiment to build upon this work, which tests bacterial biofilm formation in a variety of gravity regimes — for example, microgravity, Martian gravity or even levels found in the International Space Station.

The paper, "MARSBOx: Fungal and Bacterial Endurance From a Balloon-Flown Analog Mission in the Stratosphere," was published Feb. 22 in Frontiers in Microbiology. It was authored by Marta Cortesão, Katharina Siems, Stella Koch, Ralf Moeller, Kristina Beblo-Vranesevic, Elke Rabbow and Thomas Berger, German Aerospace Center; Michael Lane, Leandro James and Prital Johnson, NASA Kennedy Space Center; and Samantha M. Waters, Sonali D. Verma and David J. Smith, NASA Ames Space Center.

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