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They’re small. You might mistake them for yellow crumbs on the counter top. Now imagine them on an asteroid flying through the galaxy. A planet gets in the asteroid’s way. Three, two, one impact. If they happen to find water, the yellow crumbs suddenly become something much bigger – life on another planet

Sound like science fiction? Not entirely. The little yellow crumbs are real: dried-out versions of Methanosarcina barkeri, a methane-producing bacterium. Kevin Sowers, a Professor of Marine Biotechnology at UMBC whose work is funded by NASA, and his team found that the bacteria can remain in their dried-out state for at least 25 years and who knows, possibly more.
“These bacteria have innate ability to survive extended periods of desiccation," says Sowers. “And when they’re in that desiccated state they can survive in what would normally be lethal conditions.” Sowers and his team propose that this ability is a type of survival mechanism.

To determine the bacterium’s survival time in the air, which is normally toxic to these microorganisms, Sowers and his team removed the water from the bacterial cells, a process known as desiccation. This left the cells in conditions that simulate the driest conditions on Earth. These desiccated cells, the researchers discovered, could survive for 30 days in the air with negligible loss of viability.

Then, says Sowers, “I knew I had some 25-year old desiccated cells of, Methanosarcina thermophila, [closely related to M. barkeri] in the lab, so once we developed the method for quantifying survival with freshly dried cells I included the old material.” Sure enough many of the cells came back to life when rehydrated. “That experiment,” says Sowers, “enabled us to look at the long-term survival of cells.” Unfortunately, he adds, “I cannot take credit for planning the experiment 25 years ago.”

Sowers and his team think that the prolonged survival of these cells in a dried-out state, which could occur in environments such as drained rice paddy soils, might allow these bacteria to travel long-distances here on Earth. “Soil can be picked up by the wind,” says Sowers. “We actually have these atmospheric winds that distribute microorganisms from one continent to another.” For example, he says, “they could be transported from Africa to North America."

But what about space travel? These bacteria, says Sowers, could possibly be carried on an asteroid to another water bearing planet, such as Mars, where they might survive. Researchers think there is water below the surface of Mars, and in theory, these bacteria would be able to survive the dry periods. Scientists know there is methane generated on Mars, Sowers says, but they don’t yet know whether it’s biologically or geologically produced. “If the methane is biologically produced these bacteria, or bacteria very similar to them, could be prime candidates for the methane’s source.”

The team’s next step, Sowers says, is to look at what genes are important for the cells to survive being a dried out. . Sowers and his team already know that the bacteria undergo cellular changes that prepare them for the transition from a hydrated to desiccated state. “We want to find out what the actual mechanisms are that allow these organisms to adapt and survive in that state,” says Sowers. Those preparations could help them get suited up for space travel.

Accepted for publication in Applied and Environmental Microbiology

Anderson K., Apolinario E., Sowers K. 2012. Desiccation as a Long-Term Survival Mechanism for the Archaeon Methanosarcina barkeri. Applied and Environmental Microbiology.

Publication: March 2012