Some Earth bacteria survive and grow at extremely low pressure, may aid Mars research

Jan 08, 2013 by Robert H. Wells
UF study: Some Earth bacteria survive and grow at extremely low pressure; may aid Mars research
Twenty-six bacteria typically recovered from spacecraft were examined by UF researchers to see if they could grow under low pressure, temperature and oxygen conditions like those found on Mars. Plate A shows the control group grown under standard Earth pressure (1013 millibars) and oxygen and at 86 degrees Fahrenheit. Plate B shows the bacteria that can survive when temperature is dropped to freezing. Plate C shows the bacteria that survived with freezing temperature and no oxygen. Plate D shows bacterial growth at pressure as low as that on Mars (7 millibars), no oxygen and freezing temperature. Only one bacterium, Serratia liquefaciens, survived the harsh conditions. Arrows indicate locations of Serratia liquefaciens. Credit: Schuerger et al.

(—University of Florida researchers have discovered for the first time that some Earth bacteria can live under the same low pressure conditions found on Mars.

The results could help scientists protect from contamination by Earth bacteria during spacecraft missions, as well as aid in the search for life on that planet.

The researchers reveal their findings in two studies, one published in late December in the journal and one published online today by the journal Astrobiology.

"As we send spacecraft to Mars, we want to have confidence that we're not going to contaminate the landing sites," said Andrew Schuerger, a co-author of the studies and a research assistant professor in UF's plant pathology department.

Understanding the minimum set of conditions required for and replication on the is key, said Schuerger, a member of UF's Institute of Food and Agricultural Sciences.

Wayne Nicholson, also a co-author of the studies and a professor in the UF/IFAS microbiology and department, said he and Schuerger are interested in investigating if Earth bacteria can grow in the Martian environment.

"We want to know, once you transport an Earth bacterium to Mars, can it survive, let alone grow?" Nicholson said.

Schuerger and Nicholson found bacteria in the genera Serratia and Carnobacterium that could survive under the Mars conditions of low oxygen, freezing temperatures and 7 millibars of atmospheric pressure. In comparison, pressure at sea level on Earth is about 1,013 millibars.

UF study: Some Earth bacteria survive and grow at extremely low pressure; may aid Mars research
Growth of Carnobacterium isolates. Plate A shows growth with freezing temperatures and Earth pressure and atmosphere. Plate B shows growth with freezing temperatures, low oxygen and Earth pressure. Plate C shows growth with freezing temperatures, low pressure and low oxygen. Plate D shows the same plate as in C, but after one additional day of incubation on the laboratory bench (i.e., at room temperature, Earth atmospheric composition and pressure). Credit: Nicholson et al.

With these discoveries, new experiments to test whether these hardy bacteria can survive the more than 17 harsh factors on the surface of Mars—including high salt levels, and severely dry conditions—can now be conducted.

By identifying which the bacteria can survive, scientists can more readily identify locations on Mars with these conditions because they may be at the most risk for contamination.

And although these areas may be at most risk, their characteristics may also make them conducive for possible Martian microbial life, Nicholson said.

"It's a conundrum," he said. "Because if you're looking for life, you want to go to the places that are most likely to harbor life, and of course those are the very same places that are most sensitive to being contaminated by Earth organisms."

Preventing the escape of Earth microbes is important for several reasons, the researchers said. One of them is to minimize the probability of a "false-positive," i.e., detecting Earth microbes while searching for Mars microbes.

All spacecraft and equipment are carefully cleaned before launch, and the harsh conditions of interplanetary space are likely to reduce, but not eliminate, many viable microorganisms prior to landing.

One of the reasons scientists are interested in finding bacteria on Mars is to address the theory that planets are not biologically isolated. If bacteria are found on Mars, they can be genetically tested to see if they are related to Earth bacteria. If they aren't, it could mean life started in two different places. If they are related, it could mean life began on one planet and was transferred to another, possibly as the result of an asteroid impact.

While both studies examined the abilities of bacteria to grow at low pressures, each examined different bacteria.

For the PNAS study, researchers looked at growth of bacteria recovered from boring 40 to 70 feet into Siberian permafrost, while the Astrobiology study examined bacteria commonly found on spacecraft.

Some 10,000 bacteria were screened in the permafrost study for their ability to survive under low pressure, temperature and oxygen conditions. Of this number, six—all members of genus Carnobacterium—survived and grew.

In the Astrobiology study, 26 bacteria typically recovered from spacecraft were examined to see if they could grow under low pressure, temperature and oxygen conditions. Only one bacterium, Serratia liquefaciens, survived the harsh conditions.

Carnobacteria represent microorganisms that live in cold environments, such as deep within permafrost, whereas Serratia liquefaciens is a common bacterium found in more temperate environments like human skin, fish, plants and soil.

Schuerger called the discoveries "exciting" but cautioned that it does not mean bacteria can grow on current-day Mars.

"It opens up much more complex research that was not previously available to us because we didn't know if anything could grow at 7 millibars," he said. "But there are still numerous biocidal and inhibitory factors on the surface of Mars that are likely to inhibit the growth of terrestrial microorganisms at the surface."

Explore further: Magnitude-7.2 earthquake shakes Mexican capital

More information: The PNAS study is available at and the Astrobiology study is at

Related Stories

Mars Contamination Dust-Up

May 19, 2010

A new study finds that microbes on spacecraft might be able to survive on Mars longer than previously thought. The key to their survival? Dust.

Microbe risk when rover wheels hit martian dirt

Sep 06, 2011

Earth microbes trying to make it to Mars must survive sterilization in NASA's clean rooms, harsh cosmic rays during months of space travel, and the Red Planet's unforgiving surface environment. But any bacteria ...

Recommended for you

Magnitude-7.2 earthquake shakes Mexican capital

Apr 18, 2014

A powerful magnitude-7.2 earthquake shook central and southern Mexico on Friday, sending panicked people into the streets. Some walls cracked and fell, but there were no reports of major damage or casualties.

User comments : 0

More news stories

China says massive area of its soil polluted

A huge area of China's soil covering more than twice the size of Spain is estimated to be polluted, the government said Thursday, announcing findings of a survey previously kept secret.

UN weather agency warns of 'El Nino' this year

The UN weather agency Tuesday warned there was a good chance of an "El Nino" climate phenomenon in the Pacific Ocean this year, bringing droughts and heavy rainfall to the rest of the world.

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...