Microorganisms survive one step closer to Mars environment

University of Arkansas researchers have moved one step
closer to growing microorganisms under Mars-like conditions by suspending
them in water containing dissolved matter from Mars soil simulant.

D. Ryan Ormond, Curtis R. Bekkum and Timothy Kral, associate professor of
biological sciences, report their findings at 10:30 a.m. Wednesday, May 23,
at the American Society for Microbiology meeting in Orlando.

"We’ve eliminated one factor," said Kral, bringing them one step closer to
approaching conditions on Mars.

The researchers work with methanogens, microorganisms of the group Archaea.
These organisms grow under anaerobic conditions, often in extreme
environments, so Kral believes they may provide clues to the type of life
that might be found below the surface of Mars. Methanogens can be found
deep in the ocean, in the earth’s crust or even in a cow’s stomach, all of
which are environments that might be considered harsh like the conditions
found on Mars.

Two years ago, Kral became the first scientist to grow microbes under some
of the conditions found on Mars. Now he and research assistants Bekkum and
Ormond have refined their experiments to eliminate one factor likely not
found on Mars — a standard buffer used to keep the methanogens in
suspension so they don’t disintegrate.

The researchers added Mars soil simulant in varying amounts to de-ionized
water, then mixed it overnight. They decanted the mixture the next day
and used the liquid fraction to wash and suspend the methanogens. The
suspensions were added to Mars soil simulant in sealed anaerobic tubes and
incubated, then analyzed for methane metabolism, an indicator of methanogen
growth.

The samples were compared to a control that was suspended in a standard
sodium hydroxide buffer with bubbled carbon dioxide gas.

"We can use the liquid fraction of water mixed with soil simulant to suspend
the cells, and the organisms will grow," Kral said.

The methanogens grew in the liquid fraction composed of water and simulant,
although not as well as they did in the standard buffer. The researchers
hypothesize that the pH, which was lower for the liquid fractions, may have
reduced growth.