Mono Lake. Credit: Wikimedia Commons
Every life form we know of needs phosphorous to survive. The DNA responsible for our very existence owes its structure to the element; phosphorus makes up the backbone of the double helix. But in 2010, a study in Science seemed to refute that notion. It was one of the most controversial studies in recent memory—but now new research suggests that it was wrong.
The original research, led by Felisa Wolfe-Simon, described a microbe called GFAJ-1, which flourishes in California's Mono Lake by using arsenic in place of phosphorous. Arsenic is chemically similar to phosphorous, but it's also toxic.
The idea that arsenic could replace one of the basic building blocks of life was unheard of and caused an uproar in the scientific community. Some hailed the discovery as proof that life could exist in strange forms on other planets. Others were waiting for the results to be repeated by another lab and said the paper had been published too soon. Now, two years later, another lab has followed up on the work and published its own study in Science.
The new research found that the microbe does, in fact, need phosphorous to survive—it just doesn't need that much of it. Instead of using arsenic in place of phosphorous, the scientists say, the bacteria simply can tolerate extremely high concentrations of the toxic chemical.
One of the labs tasked with reproducing the results from the 2010 paper couldn't grow the microbe with arsenic alone. Researchers needed phosphorous to encourage the bacteria to grow. Another lab didn't find any evidence that arsenic was replacing phosphorous in the biochemistry of the organism.
It seems, then, the GFAJ-1 isn't quite as extraordinary as first believed. But though it doesn't represent an alien form of life, the microbe manages to survive in a hostile, arsenic-rich environment. So researchers are going to continue to look into how the organism survives and thrives in this inhospitable (at least to us) place.