Methane-producing Microbes Could Survive the Low Pressure and Extremely Thin Air of Mars, Study Suggests

A new study carried out by researchers from the Arkansas Center for Space and Planetary Sciences (ACSPS) at the University of Arkansas suggests that some terrestrial organisms such as methanogens (the methane-producing microbes) could survive the extremely thin air of Mars.

The detailed findings of the study, titled “Low Pressure Tolerance by Methanogens in an Aqueous Environment: Implications for Subsurface Life on Mars,” have been published in the journal Origins of Life and Evolution of Biospheres, and researchers suggest the findings of this study may hold clues to finding life on the red planet.

In this study researcher tested the survivability of four species of methanogens—the simplest and most ancient organisms on Earth—to see how they would withstand the environmental conditions analogous to those present on Mars. These methanogens were found in samples of deep volcanic rocks along the Columbia River and in Idaho Falls. Methanogens classified as archaea, that is, a microorganism species which doesn’t need oxygen to survive. Methanogens are commonly found in wetlands, ocean environments, and even in the digestive tracts of animals. These microorganisms consume CO2 and hydrogen to produce methane as a metabolic byproduct.

According to NASA, its various missions have demonstrated presence of methane on Mars, although its source is not yet confirmed. Some scientists have proposed that methanogens living beneath the surface on Mars could be producing this gas.  Evidence also suggests that Mars had lakes, rivers, and seas billions of years ago, and it is possible that life would have developed during that period on Mars when it was wet.

“One of the exciting moments for me was the detection of methane in the Martian atmosphere,” says Rebecca Mickol, an astrobiologist at the ACSPS and the lead author of the study.

“On Earth, most methane is produced biologically by past or present organisms. The same could possibly be true for Mars. Of course, there are a lot of possible alternatives to the methane on Mars and it is still considered controversial. But that just adds to the excitement.”

Mickol and her team was issued a three-year grant back in 2012 from NASA Exobiology & Evolutionary Biology Program to carry out this study. The team experimented with four species of methanogens—Methanosarcina barkeri, Methanococcus maripaludis, Methanothermobacter wolfeii, and Methanobacterium formicicum. The microbes were grown in test tubes within liquids, and deprived of oxygen. These microbial samples were fed hydrogen gas, and the liquids were covered with cotton swabs. The cotton swabs were also covered with dirt to simulate Martian surface, and the insides of test tube were subjected to low pressures. The low pressure conditions were created using the Pegasus Chamber, an instrument operated by the ACSPS in their W.M. Keck Laboratory for Planetary Simulations.

The team found that these microorganisms survived low pressures of 6 to 143 millibars for periods of between 3 and 21 days. The results suggested that these microorganisms don’t need a dense atmosphere to survive and that they can withstand periodic contact with the Martian atmosphere.

“These experiments show that for some species, low pressure may not really have any effect on the survival of the organism,” Mickol said.

The details results of the study have been published in the journal Origins of Life and Evolution of Biospheres.