New bacteria redefines 'life as we know it'

A recently discovered microbe has DNA unlike any other life form on Earth. It is able to substitute arsenic for phosphorus, and it may help us understand how life could prosper elsewhere.

This is a NASA image of the microbe GFAJ-1 grown on arsenic. The microbe is the first known life to be able to use arsenic in its DNA structure in place of phosphorous, which is used by all other known life forms. NASA

NASA scientists have discovered a new type of bacteria that is able to substitute arsenic--a poison to most living creatures--as a biological building block, something no other known life form on Earth can do, the agency said today.

In a press conference held at NASA's Washington D.C. headquarters, scientists announced that they had discovered a new form of bacteria, known as GFAJ-1, in California's Mono Lake that has DNA completely foreign to anything ever before found on Earth. It has the ability to substitute arsenic at the DNA level for phosphorus.

That would distinguish it from every other form of life known to man, all of which, no matter how diverse, are based on the same six elements, phosphorus, sulfur, carbon, hydrogen, oxygen, and nitrogen. But after months in the laboratory, the bacteria that was found in Mono Lake--which is known for its unusual chemistry, including very high levels of salinity, alkalinity, and arsenic--was found to have substituted arsenic atoms for phosphorous atoms in its cells.

"We've discovered an organism that can substitute one element for another," said Felisa Wolfe-Simon, a NASA astrobiology research fellow at the U.S. Geological Survey in Menlo Park, Calif. "We've cracked open the door to what's possible for life elsewhere in the universe."

Although there had been speculation that NASA's announcement would revolve around life--perhaps bacteria--found elsewhere, such as Mars, the news does keep us here on Earth.

But Wolfe-Simon said that by discovering a microbe that has this adaptable DNA, it forces scientists to question what they've long held as true--that all life was based on the same six components.

"The newly discovered microbe, strain GFAJ-1, is a member of a common group of bacteria, the Gammaproteobacteria," NASA wrote in a release. "In the laboratory, the researchers successfully grew microbes from the lake on a diet that was very lean on phosphorus, but included generous helpings of arsenic. When researchers removed the phosphorus and replaced it with arsenic, the microbes continued to grow. Subsequent analyses indicated that the arsenic was being used to produce the building blocks of new GFAJ-1 cells."

NASA feels that this discovery is important because it will help scientists with many areas of future research, such as the "study of Earth's evolution, organic chemistry, biogeochemical cycles, disease mitigation, and Earth system research. These findings also will open up new frontiers in microbiology and other areas of research."

 

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