Candy-pink lagoon raises hopes for life on Mars
Algae found in a candy-pink Spanish lagoon is giving scientists hope that life could or may once have existed on Mars. Called Dunaliella salina EP-1, the organism gives the Laguna de Peña Hueca at Lake Tirez in La Mancha its distinctive color, and it lives in high salt and sulfur concentrations similar to those found at the buried lake at the Martian ice caps or the global ocean under the ice crust of Jupiter's moon Europa.
The recent news that there is a lake of liquid water under the southern polar ice cap on Mars provided new hope that life could still exist there, but this was soon tempered by the discovery that it's very likely that this water may have as much salt, sulfur, and other minerals as the dead lakes and seas found on Earth. However, research by Rebecca Thombre (of the Department of Biotechnology at the Modern College of Arts, Science and Commerce in Shivajinagar, India) and Felipe Gómez (of the Centro de Astrobiología, Madrid) indicates that it is possible for at least one form of microorganism to live under even those extreme conditions.
What they found in samples from Laguna de Peña Hueca is a subgenus of the halophilic (salt-loving) algae Dunaliella, that seems perfectly happy in the very salty environment. The red cells of the algae are what give the lagoon its pink color, along with the bacteria Halomonas gomseomensis PLR-1.
"Dunaliella salina EP-1 is one of the most salt-tolerant extremophiles that we've found," says Thombre. "Microbes find it difficult to tolerate hypersaline environments because water needed for the cell to function tends to flow out through the cell-membrane into the salty surroundings. The algae survive the conditions at Peña Hueca by producing molecules like glycerol that mimic the external salt concentrations within the cell and counteract water-loss."
The researchers say that the presence of these microorganisms not only increase the likelihood of finding evidence of life on the Red Planet, but might also explain how it got there. If they can survive in very mineral-rich conditions, they also have the potential to derive nutrients and energy from rock itself, meaning that life could have traveled to Mars in the ancient past on meteors blasted away by asteroid collisions from the primeval Earth.
"The resilience of extremophiles to the conditions of Mars analogs on Earth demonstrate their potential to thrive in Martian soils," says Gómez. "This has implications for planetary protection, as well as how algae might be used to terraform Mars."
The research results will be presented at the European Planetary Science Congress (EPSC) 2018 in Berlin.