NASA Announces Discovery of Life That Thrives on Arsenic

NASA Announces Discovery of Life That Thrives on Arsenic

At a press conference today, NASA astrobiology research fellow Felisa Wolfe-Simon announced the discovery of an organism unlike any other on Earth: “a microbe that can substitute arsenic for phosphorus.” The finding questions the assumption of life’s basic components and opens the door for new hypotheses of what life may look like not only on Earth, but on other planets.

Wolfe-Simon, who led the research team, described herself as “always interested in exceptions to the rule,” an outlook that prompted her to find out if there was a living organism that could substitute one of the building blocks of life – phosphorous – with a toxic, yet chemically similar element, arsenic. This question led the team to the harsh conditions of Mono Lake in Northern California, which, despite having high levels of arsenic and three times the salt of seawater, is teeming with life. There they found a microbe, dubbed GFAJ-1. The team took samples of mud at the lake, and, back in the laboratory, created almost identical conditions – except for the elimination of phosphorous and the introduction of high doses of arsenic. The result was extraordinary: “not only did [the microbe] cope,” said Wolfe-Simon, “but it grew and it thrived; and that was amazing.” When the researchers measured the arsenic concentration in the organism, they found it was behaving like phosphorous would within the cell – as the backbone of the DNA.

Putting the role of phosphorous in context, Arizona State University Professor James Elser, explained that life, as is traditionally conceived, relies on phosphorous. Its scarcity on Earth and the concern that it may be running out has prompted many to look for solutions. The research discussed today, of what he described as a “clever organism” capable of evolving to do without the crucial element, may yield new ideas. Elser suggested that practical applications may be explored, like waste water treatment, and bio-energy that does not require phosphorous-based fertilizer. But first in line is the reconsideration of the basic assumption, which Elser has used repeatedly in his teaching, that life needs phosphorous to survive. “I have to thank you and blame you [Felisa] for making our lives more difficult,” he joked.

While still considering the research significant, Steven Benner, Distinguished Fellow at the Foundation for Applied Molecular Evolution, was wary of jumping to conclusions. Benner described himself as the chemist brought in to dampen the excitement as he explained why chemists would see this as an “exceptional result” requiring “exceptional evidence.” While questions remain to prove this “exceptional claim,” he said that the organism would be there for further testing. Benner pointed to a 2007 National Academy of Science’s report, The Limits of Organic Life in Planetary Systems — the “weird life” report — to suggest that the conditions that make arsenic too unstable on Earth may be useful in radically different environments, like the cold environment of Titan.

In this respect, the discovery will impact NASA’s search for life, particularly with respect to defining “habitability” outside of Earth, explained Pamela Conrad, astrobiologist at NASA’s Goddard Space Flight Center. “We still don’t know what might make a habitable environment,” she explained. This research suggests that where arsenic may have been thought of as life-prohibiting and toxic, it may be found to be, if not essential for habitability, at least tolerable for some organisms. Conrad said the impact the discovery would have on NASA programs would be to challenge scientists to “think more broadly about environments one might characterize as habitable.”

According to Wolfe-Simon, the implications are broad. She said that the discovery was “not about arsenic or Mono Lake but thinking about life in a planetary context” and its potential for questioning what was previously thought was possible for life. This microbe shows a “different way to do business” and “it has solved the challenge of being a life in a very different way than we knew of.” The questions arising out of this discovery will open the door for new areas of research and “it will take an army of scientists” to explore, she said.

According to a questioner, the news that NASA would make a significant announcement related to the search for life was met with some disappointment from members of the public when the researchers did not pull an “ET out of a hat.” Mary Voytek, Director of the Astrobiology Program at NASA Headquarters, said that she was sorry about this disappointment but explained that, “from our perspective, this is a phenomenal finding.” She added that it “will fundamentally change how we define life [and] what we look for in life.”

According to the NASA press release, the research team was made up of scientists from the U.S. Geological Survey, Arizona State University in Tempe, Lawrence Livermore National Laboratory, Duquesne University, and the Stanford Synchrotron Radiation Lightsource. The findings will be published in today’s edition of Science Express (subscription required).

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