This morning word got out of the astrobiological discovery NASA was talking up at the beginning of the week. The Space Agency had found bacteria in a poisonous lake in California with a previously unheard of DNA makeup. Instead of being comprised of the six building blocks of life that we previously believed to be the basis of every living thing, the DNA showed that the bacteria replaced one of the building blocks, phosphorus, with arsenic.
NASA spoke about the discovery this afternoon at a press conference in Washington. The discovery that not all living things are composed of these six components means that the chance another kind of life exists outside of our planet has increased significantly.
The highly poisonous arsenic is chemically quite similar to phosphorus. Speaking in Washington today, Felisa Wolfe-Simon, a NASA astrobiology research fellow and the research team's lead scientist, said it was already known that microbes could breathe arsenic; however, this is the first time a microbe has been found to use arsenic in its building blocks.
NASA says the new microbe, GFAJ-1, is a member of a common group of bacteria, the Gammaproteobacteria. Researchers in a lab were able to successfully grow microbes from the lake on a diet that was "very lean on phosphorus, but included generous helpings of arsenic." Researchers then removed the phosphorus and observed that not only did the microbes continue to grow, but the arsenic was also being used to produce building blocks of new GFAJ-1 cells.
"The definition of life has just expanded," Ed Weiler, NASA's associate administrator for the Science Mission Directorate at the agency's HQ, said today. "As we pursue our efforts to seek signs of life in the solar system, we have to think more broadly, more diversely and consider life as we do not know it."