Methane-Producing Organisms Found in Utah Desert

http://www.usc.edu/uscnews/stories/11771.html

Work Bolsters Life on Mars Theories
By Lori Oliwenstein
USC Press Release
November 1, 2005

A Keck School scientist and his collaborators are the first to find
methane-producing bacteria in arid desert soils, providing a
springboard
for future experiments on the distant planet.

Evidence of methane-producing organisms can be found in inhospitable
soil environments much like those found on the surface of Mars,
according to experiments undertaken by scientists and students from the
Keck School of Medicine of USC and the University of Arkansas and
published online in the journal Icarus.

The results, they said, provide ample impetus for similar "biodetection
experiments" to be considered for future missions to Mars.

"Methane-producing organisms are the ones most likely to be found on
Mars," noted Joseph Miller, associate professor of cell and
neurobiology
in the Keck School and one of the study's lead researchers. "And, in
fact, methane was detected on Mars last year."

Methane is considered to be a biological signature for certain living
organisms that metabolize organic matter under conditions of low or no
oxygen.

Terrestrial methanogens (methane-producers) are typically found in
environments largely protected from atmospheric oxygen, such as peat
bogs, oceanic methane ices and anoxic levels of the ocean. But they
previously had not been detected in an arid desert environment.

To see if methane could be found in Mars-like soil, the investigators
collected soil and vapor samples from the arid environment of the Mars
Desert Research Station in Utah and then compared them with vapor
samples taken from the Idaho High Desert and soil samples from Death
Valley, the Arctic and the Atacama desert in Chile.

Three of five vapor samples from the Utah site showed the presence of
methane; there was no methane found in any of the vapor samples from
Idaho. Similarly, while five of 40 soil samples from Utah produced
methane after the addition of growth medium to the samples - indicating
that the methane was being given off by a biological organism, most
likely a bacterium - none of the other soil samples showed signs of
methane production.

Finding methane in the Utah desert is no guarantee that
methane-producers exist on Mars, said Miller, who previously has
analyzed data from the Viking Lander missions and found that soil
samples taken in the 1970s from the Martian surface exhibited a
circadian rhythm in what appeared to be nutrient metabolism, much like
that present in terrestrial microbes.

However, Miller said, this recent experiment does provide "proof of
principle [in that] it improves the case that such bacteria can and
might exist on the Martian surface." And, he added, that surely
warrants
further investigation during future missions to Mars.

In conclusion, the researchers wrote, "The detection of methane,
apparently of biological origin, in terrestrial desert regolith bodes
well for future biodetection experiments in at least partially
analogous
Martian environments."