Bacteria subjected to the same harsh conditions in outer space have proven to be surprisingly hardy, raising hopes they could survive in other places in the solar system, too.
Advanced technologies leading to astounding discoveries have brought humanity several steps closer to finding life as known in other worlds. In the last month alone, researchers have discovered organic material on Mars and Saturn's moon Enceladus.
In earlier explorations, experts have confirmed that Europa, one of Jupiter's moons, sends geyser-like plumes of salty water into its atmosphere, suggesting the existence of hydrothermal vents similar to that of Earth where the first microbes appeared.
Now, new research affirms that some of Earth's hardiest microbes could possibly survive in the extreme climates of Mars, Enceladus, Europa, and other worlds. By subjecting bacteria to a different set of chemical cocktails, scientists have found that microbes can withstand conditions akin to the harsh environments outside of Earth.
An international team of researchers from Germany, the United States, and the UK chose to work with a microbe called Planococcus halocryophilus, a bacteria typically found in the frozen soils of the Arctic region.
They subjected the bacteria to a variety of salty chemical solutions, including sodium chloride, magnesium chloride, and calcium chloride. The bacteria were also immersed in perchlorate, a highly toxic chemical compound that is found in small amounts in the soils of Mars.
Lead researcher Jacob Heinz of the Center of Astronomy and Astrophysics at the Technical University of Berlin says they chose an array of compounds to try and mimic the chemical composition of Mars.
Bacteria Surviving In Extreme Conditions
The researchers wanted to know how much perchlorate was needed to kill the bacteria. As they suspected, the bacteria did not survive when exposed to high concentrations of the poisonous compound. Even at a lower temperature of -22 Fahrenheit, where bacteria are known to fare better, the microbes only showed minimal improvement.
However, Heinz says this does not preclude life on Mars or other places. Martian soil has less than 1 percent in weight of perchlorate. The researchers say bacteria exposed to solutions of 10 percent perchlorate can still survive.
Theresa Fisher of the Arizona State University's School of Earth and Space Exploration says the research may demonstrate how bacteria can adapt in new ways to their environment. Fisher studies how microbes can survive in other planets.
"I'd be surprised if microbes haven't evolved a way to deal with that toxicity," Fisher says. "Bacteria, when stressed, have shock responses. They manufacture specific proteins that help them adjust, survive, and cope with detrimental environments."
In the driest regions of the Chilean Atacama desert, for example, scientists have found that bacteria do not only survive in the harsh conditions, they thrive in environments with high levels of perchlorate and other toxic compounds.
The Salt Factor
Another factor the researchers wanted to test was salt concentrations. Lower temperatures are generally more favorable for microbes. However, the chemical composition of the saline solution also plays a huge role.
Bacteria placed in normal table salt (sodium chloride), for example, perished after two weeks of exposure at room temperature. However, as the temperature went down to 5 degrees Fahrenheit, almost all of the bacteria survived.
Survivability when exposed to magnesium chloride and calcium chloride at room temperature varied, but the bacteria displayed high survival rates at -22 degrees Fahrenheit.
The researchers also subjected the bacteria to freeze-thaw cycles similar to the rapid changing of temperatures on Mars. An average day on Martian land registers around -72 degrees Fahrenheit, with the polar regions dropping as low as -193 degrees Fahrenheit.
They found that bacteria in saltier solutions were better able to endure the extreme temperature changes. When the researchers added 10 percent table salt to their solutions, mortality rates dropped from 20 percent to 7 percent.