Felisa Wolfe-Simon, the research team's lead scientist, processing mud from Mono Lake. Photo by Henry Bortman

Researchers found the microbes called strain GFAJ-1 in Mono Lake, Calif., and successfully grew them based on a diet that included arsenic and phosphorus. Although the organisms grew better with phosphorus, they continued to thrive when phosphorus was replaced with arsenic, an element poisonous to most known life on the planet. 

Phosphorus has long been considered a basic building block of life in addition to carbon, hydrogen, nitrogen, oxygen and sulfur. But the discovery of GFAJ-1-- an extreme life form under extreme conditions on Earth--broadens the scope of the search for life on other planets and harsh environments, researchers said. 

"We know that some microbes can breathe arsenic, but what we've found is a microbe doing something new -- building parts of itself out of arsenic," said Felisa Wolfe-Simon, a NASA astrobiology research fellow and the research team's lead scientist. "If something here on Earth can do something so unexpected, what else can life do that we haven't seen yet?" 

The study is published Thursday in Science Express.

A key part of the work investigated whether arsenic actually became part of GFAJ-1s' biochemical machinery, such as DNA and proteins, when the microbes were grown on arsenic. Researchers found the microbes used arsenic as a substitute for phosphorus in their cell components. 

Mono Lake was a suitable choice to explore due to its harsh and unusual environment, researchers said. The lake has high salinity, high alkalinity, and high levels of arsenic because it has no outlet and dissolved matter builds up over time.

NASA helped fund the research. Although the study did not surround the discovery of extraterrestrials, speculation surged in the online community that it did after NASA issued a press release Monday. The space agency stated a news conference would be held Thursday to discuss "an astrobiology finding that will impact the search for evidence of extraterrestrial life" but did not disclose research details.

“We haven't discovered alien life; far from it,” said Bruce Betts, director of projects at The Planetary Society, a space exploration advocacy group that was not involved in the work. “[But] it's definitely along the direction of once again,  life on Earth is flexible and more variable than we had guessed and anytime you do that... you up the chance that we give to finding life elsewhere in the universe.”

The study is expected to contribute to research areas such as Earth's evolution, organic chemistry and disease mitigation. 

Reach reporter Len Ly here. Follow her on Twitter here.