Antarctic fungi on the ISS: Mimicking Martian UV

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  • Published: Feb 1, 2016
  • Author: David Bradley
  • Channels: UV/Vis Spectroscopy
thumbnail image: Antarctic fungi on the ISS: Mimicking Martian UV

Fungi in space

Section of rock colonized by cryptoendolithic microorganisms and the Cryomyces fungi in quartz crystals under an electron microscope. Credit: S. Onofri et al.

Microscopic fungi isolated from under Antarctic rocks can survive exposure to radiation at levels known to exist on Mars, according to research carried out on the International Space Station, ISS, with almost two-thirds of cells remaining intact after eighteen months and stable DNA being present. The discovery will keep alive the hope of one day finding evidence of microbial life on the Red Planet. Lichens from the Sierra de Gredos in Spain and the Austrian Alps were also conveyed to the ISS for the same experiments.

Scientists believe that The McMurdo Dry Valleys of Antarctic Victoria Land are the terrestrial environment that most closely resembles the dry and incredibly chilly conditions found on Mars. They are one of the driest and most hostile environments on Earth where strong winds constantly scour away at snow and ice and only the hardiest of microorganisms, cryptoendolithic, can survive in cracks in rocks, and a few tough lichens, cryptoendolithic, can survive in spaces within porous rocks, withstanding the weather.. Several years ago, a European team collected samples of two species of cryptoendolithic fungi, Cryomyces antarcticus and Cryomyces minteri, from this region with the aim of sending the samples to the ISS where even more Mars-like conditions could be simulated and the way in which these microbes responded be observed.

The microscopic fungi were put in containers on an experiment platform - EXPOSE-E - developed by the European Space Agency to withstand extreme environments and carried about NASA's space shuttle Atlantis to the ISS as well as being placed outside the Columbus module with the help of an astronaut from the team led by Belgian Frank de Winne.

Vacuum unpacked

For 18 months half of the Antarctic fungi sample were exposed to Mars-like conditions comprising an atmosphere of 95% carbon dioxide, 1.6% argon, 0.15% oxygen, 2.7% nitrogen and 370 parts per million of water and under a pressure of 1 kilopascal (about one hundredth of Earth's atmospheric pressure at sea level. The samples were exposed to cosmic radiation and up to 200 nanometre ultraviolet radiation carried through optical filters to mimic exposure on Mars, another sample had no UV exposure and one was exposed at lower energy.

"The most relevant outcome was that more than 60% of the cells of the endolithic communities studied remained intact after 'exposure to Mars', or rather, the stability of their cellular DNA was still high," explains team member Rosa de la Torre Noetzel from Spain's National Institute of Aerospace Technology (INTA). She explains that this work, published in the journal Astrobiology, forms part of an experiment known as the Lichens and Fungi Experiment (LIFE), "with which we have studied the fate or destiny of various communities of lithic organisms during a long-term voyage into space on the EXPOSE-E platform."

Space survivors

The results will allow biologists interested in the possibility of life on Mars to weigh up just how inhabitable conditions might be given the evolution of a sufficiently hardy microorganism. "This information becomes fundamental and relevant for future experiments centred around the search for life on the red planet," adds De la Torre.

In work coordinated from Italy by Silvano Onofri from the University of Tuscia, two species of lichens - Rhizocarpon geographicum and Xanthoria elegans - which are capable of surviving extreme high-mountain environments were also studied and again specimens were exposed to Mars-like conditions in space. Another range of samples of both the lichens and the microscopic fungi, was subject to extreme temperature variations in space from -21.5 to +59.6 degrees Celsius as well as high cosmic radiation levels and near vacuum conditions. The samples were also exposed to ultra-violet radiation. After their 18 month voyage it was found that two species of lichens exposed to Mars conditions had double the metabolic activity of their terrestrial counterparts and in the case of X. elegans levels approaching 80% increased activity were observed, although photosynthetic activity was lower in the lichens exposed to space conditions.

Related Links

Astrobiol 2015, 15, 1052-1059: "Survival of Antarctic Cryptoendolithic Fungi in Simulated Martian Conditions On Board the International Space Station"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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