For the first time, astrobiologists have found that microbes from Earth can survive and grow in the low pressure, freezing temperatures and oxygen-starved conditions seen on Mars. Until now, the lowest atmospheric pressure that researchers could grow bacteria in was just 25 millibars. That is nearly four times greater than the 7-millibar global average surface pressure of Mars.

Microbiologists Wayne Nicholson and Andrew Schuerger at the University of Florida and their colleagues analyzed microbes found in permafrost soil collected from northeastern Siberia by the Soil Cryology Laboratory in Russia. The microbes were grown for up to 28 days in nutrient-rich lab dishes at room temperature and normal air and pressure. Roughly 10,000 colonies of these bacteria were then incubated for an additional 30 days in a chamber designed to simulate the surface of Mars, keeping them at 0 degrees Celsius without oxygen and at a pressure of 7 millibars. Six colonies of bacteria grew under these severe conditions.

The findings were published online Dec. 24 in the journal Proceedings of the National Academy of Sciences.

In a companion study, Schuerger, Nicholson and their colleagues investigated 26 strains of bacteria commonly found on spacecraft, incubating them under the same Mars-like conditions. They found one bacterium, Serratia liquefaciens, could survive and grow.

The researchers do caution that while they grew these bacteria under extremely low pressure, temperature and oxygen levels, “they were also grown in a wet, nutrient-rich environment,” Schuerger said. “These are conditions that are very difficult to meet on the surface of current-day Mars.”