"Life As We Do Not Know It"

Mono Lake in California has long been known for its high levels of salt, alkaline, and arsenic, but now the lake will be known for something far more revolutionary. Led by Felisa Wolfe-Simon, astrobiologists doing research at the U.S. Geological Survey in Menlo Park, California have discovered a new form of life. Named GFAJ-1, this new life is only one of numerous strains of gammaproteobacteria on Earth, but it does something no other known organism can: it uses poisonous arsenic as a fundamental building block, substituting it in the place of phosphorus in its cell membranes and its very DNA.

The discovery of GFAJ-1 is forcing the scientific community to radically rethink the definition and the possibilities of life. The new bacteria, NASA says, is "life not as we know it." Though scientists have long recognized that some bacteria can breathe arsenic and use it for energy, until now, it was understood that everything on earth was made of the same DNA, and that DNA was built from the same six elements: carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. What Wolfe-Simon and her team discovered is that GFAJ-1 thrives on a steady diet of phosphorus, but is not negatively impacted by high doses of arsenic. More significantly, when researchers replaced all the phosphorus with arsenic, the bacteria simply substituted the new element for the phosphorus as it built its cells and DNA. Caleb Scharf, an astrobiologist at Columbia University, told The New York Times that the bacteria's amazing ability is "like if you or I morphed into fully functioning cyborgs after being thrown into a room of electronic scrap with nothing to eat."

By proving that phosphorus is not a necessary component of DNA, GFAJ-1 has opened up incredible possibilities for what else has not yet been discovered, on Earth and in space. Mono Lake, due to its unique environmental composition, has long been a NASA focus because it is thought to manifest the conditions under which early Earth life evolved. If this life grew and developed in ways similar to the newly-discovered bacteria, then this discovery also has enormous implications for the possibility of extraterrestrial life. Regarding GFAJ-1, NASA tweeted that it "will change how we search for life elsewhere in the Universe." Instead of combing space for Earth-like planets, researchers can look for new life in different places, using different methods. Life could be found on planets which were previously disregarded because they were missing so-called fundamental building blocks, the building blocks that GFAJ-1 has shown to be not-so-fundamental after all. NASA cites the bacteria's discovery as a major contribution to "the study of Earth's evolution, organic chemistry, biogeochemical cycles, disease mitigation, and Earth system research." With radical new doors opened and new life much closer to home than suspected, who knows what will be next on the horizon?

For more information, see Wolfe-Simon's study.