14 DAY TRIAL // If there is life on Mars, how does it look like? In the present conditions, Martians can be no more than bacteria. And some quite hardy bacteria.
That's why a team at University of Arkansas has checked some of the toughest bugs on Earth, three different species of methane producing microorganisms, in various soil types similar to those encountered on Mars' surface to see if there is life possible in the predilect SF location for alien life. "We had found that methanogens can grow on Mars soil stimulant, but we didn't know if they could grow on other types of soils found on Mars," said co-author Tim Kral, professor of biological sciences at the University of Arkansas.
Methanogens are ancient microbes which belong to the Archaea kingdom, distinct from bacteria, and able to live in extreme environments. That's why they are the best suited candidates to show how life might look like on Mars, with its life-unfriendly conditions, such as extreme cold; so far, organic matter has not been detected.
But methanogens thrive in harsh, anaerobic environments, like animal guts, lake bottoms, in deep parts of the ocean or in the Earth's crust. The methanogen strains were cultivated on five different substrates - clay, sand, gravel, basalt and Mars soil stimulant, in anaerobic conditions.
Glass beads were employed as a control substrate. The methanogens received hydrogen as an energy source and carbon dioxide as a carbon source. "We wanted to see if different types of rocks and soils could supply the other necessary ingredients for them to produce methane," Kral said.
On sand, gravel and Mars soil stimulant, the methane production revealed the presence of living methanogens. On basalt, the most common ground found on Mars, just one methanogen species was active and none was survived in the clay. "You have to put the parts in place before you can see the whole picture. We are currently teasing out the parts so we can build the picture", said Kral.