Discovery of Life in Deep-Sea Rocks Inspires New Search for Life on Mars

(CN) — When a researcher dyed a slice of volcanic rock more than a million years old with a material that stains DNA, he was greeted by a community of glowing green spheres surrounded by bright orange clay mineral deposits.

The discovery of microbial bacteria in solid rock from deep beneath the ocean floor naturally can be applied to the search for life on the planet Mars.

An example of a thin slice of rock prepared using special epoxy to ensure the rock held its shape while it was cut. (Caitlin Devor / University of Tokyo)

In a study published Thursday in the journal Communications Biology, researchers detail the discovery of microbial life in densely populated communities found in the fractures and veins of basaltic rock ranging from 33 million to 104 million years old.

The findings could one day be used to search for life on the red planet because the conditions found between the deep ocean and the surface of Mars are remarkably similar, according to associate professor Yohey Suzuki from the University of Tokyo.

Lava spewed out by undersea volcanoes arrive onto Earth’s surface at temperatures around 2,200 degrees Fahrenheit and eventually form into rock. Cracks in these rocks fill in with clay minerals, but consider these cracks are no larger than 0.04 inches across.

Yet, life finds a way.

Bacteria found in these narrow crevices are densely occupied with about 10 billion bacterial cells per 0.06 cubic inch. By comparison, bacteria living in mud sediment on the sea floor is around 100 cells per 0.3 inches.

In an email, Suzuki noted the lack of sunlight or photosynthetic energy is one of the most common themes the subsea samples and the surface of Mars share. Mars’ surface is “too hostile” with the same basalt rock type.

“In addition, the product of basalt-water reaction is the same: a type of clay mineral,” Suzuki said. “As clay minerals are diverse reflecting the surrounding environment from which they form. Therefore, I can say that the rock I discovered dense microbial life is very similarly hosting potential life on Mars.”

Researchers gathered rock samples on an expedition from the island of Tahiti to Auckland, New Zealand in late 2010 at three locations across the South Pacific Gyre.

Samples are estimated to be 13.5 million, 33.5 million and 104 million years old and were not near any type of hydrothermal vent or seafloor channels, giving the study authors confidence the bacteria arrived at the deposits independently.

Suzuki said the study’s roots reach back to the Martian meteorite Allan Hills 84001, which was discovered in Antarctica in 1984. A group of scientists went on to claim in 1996 they found evidence of microscopic fossils of bacteria in the meteorite, but that was proven inaccurate.

The undersea samples discovered by Suzuki and his team prods the same type of problems that dogged researchers all those years ago.

“However, we don’t know about how life can live in solid rock without any photosynthetic energy source,” Suzuki said in an interview.

Previously, researchers chipped away at rock samples in their search for life. But Suzuki followed a pathologist’s example by coating the rock samples in an epoxy that allowed him to slice thin layers without crumbling the rock.

Those samples were then washed in a dye that stains DNA and when Suzuki looked under a microscope, he saw a colony of the bacteria – now painted green – tightly packed into tunnels that glowed orange and were surrounded by black rock.

“This discovery of life where no one expected it in solid rock below the seafloor may be changing the game for the search for life in space,” Suzuki said in a statement that accompanied the study.

Suzuki and his team are working with NASA’s Johnson Space Center to formulate a plan to examine rocks collected on Mars by rovers. An email to Suzuki on the study’s implications was not immediately answered.

In a previous study by researchers from The SETI Institute, the Atacama Desert in Chile was used as trial search for life on Mars. The arid desert has a similar geography to the surface of Mars and during that mission, researchers dug up salt-resistant bacterium that thrives in sediment rock.

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