Unusual life discovered in Mexican crystal caves gives insight to astrobiologists

By Lauren Puckett

nasa-naica

The Naica mine in Chihuahua, Mexico is filled with enormous, milky white crystals, some of which house tiny organisms. Photo courtesy of NASA

BOSTON — Deep in the caves of Naica, Mexico — some 800 meters below ground, where geothermal heat pushed temperatures into the range of 113 to 140 degrees Fahrenheit — Penelope Boston found something incredible.

Within the cave’s enormous sparkling crystals, tiny microbial organisms lived in pockets of fluid. Boston’s attempts to genetically classify them proved unsuccessful. The microbes were unidentifiable with any known genus, making it likely they are new to science. And if Boston’s research is correct, they’re old geezers — anywhere from 10,000 to 50,000 years old.

Boston, head of NASA’s Astrobiology Institute, presented her findings at the American Association for the Advancement of Science’s annual conference in Boston on Feb. 17. She described how, in 2008 and 2009, her team, dressed in spacesuit-like outfits chilled by ice packs, found fluid deposits inside the Naica crystals where the organisms had survived for millennia. The caves had been pumped free of groundwater by miners searching for silver and lead, leaving behind a network of crystals for Boston and her fellow New Mexico Tech colleagues to explore.

Boston’s team has managed to grow about 65 cultures from the initial sample brought to the lab, where they kept “growing back from stubs,” she says.

The results of her study are as of yet without publication or peer review, which brings the discovery to a roadblock of scientific skepticism. For instance, what if the microbes were contaminated by the New Mexico Tech workers? Boston counters that the squad operated in sterile suits and gloves, doing surface decontamination before harvesting any crystal. In addition, almost all of the sampling was done on-site so as to minimize risk of contamination.

“We feel very confident now after eight years of working on these materials,” Boston says, “that we actually are looking at organisms that were indeed sealed within these capsules, and that these organisms remained viable and were able to be regrown.”

Boston says she is trying to get her work out there, after she finishes a reanalysis of the genetic material. But if accepted after peer review, Boston’s findings might have grand implications for life far above Naica. If bacteria can live for thousands of years in such extreme heat as Naica’s Hell, could our own bacteria survive the atmosphere of another planet, or could another planet’s microbes survive here?

It’s far from impossible that bacteria from Earth could harm an exoplanet environment, says University of South Florida, St. Petersburg biologist Norine Noonan, who presented her research alongside Boston at AAAS. Noonan, a professor interested in cell biology, warned that the science fiction-esque risk of biological contamination in outer space could easily become science fact. 

Humans are “spewing fountains of bacteria,” says Noonan, who studies the ice of Europa, the smallest of the four moons orbiting Jupiter. 

Noonan compared a bacterial outbreak on unexplored worlds to the spread of invasive species on Earth, from rabbits being introduced to Australia and quickly becoming an uncontrolled population, to the rampage of kudzu across the American South. Humans could harm other planets’ ecosystems, just as other planets’ ecosystems could harm humans.

What Boston’s discovery shows us, Noonan says, is just another example of the extreme environments life can survive, and how long they are able to survive it. As it’s possible other planets have bacteria similar to the Naica crystal creatures — due to a similar combination of rocks, water, pressure and heat — it’s also possible for humans to cross-contaminate bacteria when visiting other worlds. For this reason, it’s essential for future space missions to factor in “planetary protection,” engineering biological barriers within the spacecraft to keep both humans and aliens safe.

As Noonan signed off on her presentation, she left an image on the Powerpoint screen: Bart Simpson, scribbling the same line over and over again on a chalkboard. Noonan told the audience to pay attention to Bart’s message, because it tied together the presenters’ work with one common astrobiological theme.

Written on the board was “Science class should not end in tragedy.”

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