FAYETTEVILLE,
Ark. — University of Arkansas researchers have tested the methane production of
three different types of microorganisms in different soil types that resemble
those found on Mars to test the possibility of these soils harboring life.
Tim Kral,
professor of biological sciences at the University of Arkansas; Heaven A. Kozup
of Gwynedd-Mercy College in Pennsylvania, and UA graduate student Brandon G.
Gibson will present their findings Wednesday, May 23, at the American Society
for Microbiology in Toronto.
“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,” Kral said.
For years Kral has studied methanogens, ancient
microorganisms from the biological domain Archaea, as potential candidates for
what life might look like on Mars. At first glance, Mars appears unfriendly
toward most life forms. The planet currently contains no detectable organic
matter and has extremely cold surface temperatures. However, methanogens seem
to be a potential candidate for what life on Mars might look like -- they
produce methane and live in harsh, anaerobic environments, such as the guts of
animals, in deep parts of the ocean or in the Earth’s crust.
Kral, Kozup and Gibson cultured three different species of
methanogens on five different substrates — clay, sand, gravel, basalt and Mars
soil stimulant — in sealed anaerobic culture tubes. They used glass beads as a
control substrate. All of the tubes contained hydrogen as an energy source and
carbon dioxide as a carbon source. The researchers then measured the methane
production from each test tube for a month.
“We wanted to see if different types of rocks and soils
could supply the other necessary ingredients for them to produce methane,” Kral
said.
The test tubes
containing sand, gravel and Mars soil stimulant all produced methane,
indicating the presence of living methanogens. Only one species of methanogen
produced methane on basalt, which is commonly found in Martian soil, and none
was found in the clay, although Kral plans to re-create the experiments in a
slightly different manner.
“This is a hodgepodge of things that come
together and tell a story,” Kral said. “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.”
Kral is a
professor of biological sciences in the J. William Fulbright College of Arts
and Sciences.
ASM presentation: “Methane Production on Rock
and Soil Substrates by Methanogens: Implications for Life on Mars.”
(Session 184/N, Paper N-160)