Retraction of Controversial Arsenic-Life Paper Stirs Debate Among Scientists

Back in 2010, in a livestreamed press-conference, researchers from NASA Astrobiology Institute claimed to have discovered something that “will fundamentally change how we define life, and therefore look for it.” They reported that a microbe from a salty, alkaline Californian lake, could thrive on arsenic—an element that is toxic to most organisms.¹

Their findings, published in Science, soon stirred a controversy, with scientists pointing out flaws in the methods and interpretations. Last week, after nearly 15 years of debate, the journal retracted the study. “If the editors determine that a paper’s reported experiments do not support its key conclusions, even if no fraud or manipulation occurred, a Retraction is considered appropriate,” editor-in-chief Holden Thorp wrote in the journal’s retraction statement.² The move received mixed reactions from researchers. While some welcomed it, others questioned whether retracting the paper was the best way to correct the scientific record.

“It’s good that it’s done,” Rosie Redfield, a now-retired microbiologist from the University of British Columbia and a study critic, told Nature. “Pretty much everybody knows that the work was mistaken, but it’s still important to prevent newcomers to the literature from being confused.”

Some other scientists—including the study authors who protested the decision—are less pleased. “This is a very, very poor editorial decision,” said Sunil Laxman, a microbiologist and biochemist at the Institute for Stem Cell Science and Regenerative Medicine, who was not associated with the study. “There [was] absolutely no misconduct of any kind. This is severe editorial overreach, because correcting the literature is not the job of a journal.”

Salty Waters, an Unusual Bacterium, and a Controversy

For the study in question, Felisa Wolfe-Simon, then a researcher at the NASA Astrobiology Institute, and her team isolated a bacterium from sediments of the hypersaline, alkaline, and arsenic-rich Mono Lake. Through experiments, the researchers concluded that the strain (dubbed GFAJ-1) swapped out phosphorus for arsenic to sustain its growth and also in its DNA backbone.

“The discovery of an organism that thrives on otherwise poisonous arsenic broadens our thinking about the possibility of life on other planets, and begs a rewrite of biology textbooks,” declared a NASA press release. The bold claims first grabbed eyeballs, and soon after, raised eyebrows.

In comments accompanying the study in the print issue in June 2011, researchers argued that the conclusions seemed premature and pointed out methodological flaws such as phosphate contamination in the growth medium and dubious DNA purification steps.^3,4 Chemists noted that substituting phosphorus with arsenic in the DNA backbone would yield unstable bonds that would fall apart within a second when exposed to water.⁵

While Laxman said it seemed implausible that arsenic replaced phosphorus in the genetic material, he recalled enjoying reading the paper. “This organism that [could] grow with ridiculously high amounts of arsenic,” intrigued him.

As the study garnered more attention, biologists, including Redfield, tried to verify the claims. They found that while GFAJ-1 tolerated arsenic, it did not incorporate the element in its DNA, and still needed phosphorus for growth.^6,7 To many, including Laxman, the matter was settled.

“Science and the scientific method self-correct; things that are wrong get moved out,” said Laxman. “Hasn't the scientific method worked very well in separating…the interpretations from the conclusions?” When other groups systematically studied the bacterium and found alternate explanations, “the authors can only be accused of overenthusiasm.”

Retraction Received Mixed Reactions

But the issue was far from over, with journalists and scientists continuing debates about the paper. Back when critics questioned the findings, Science reserved retractions for cases of misconduct; since there was no suggestion of foul-play, the paper stood the test of time. However, the journal’s guidelines for retracting papers have since expanded, according to Thorp’s retraction statement.

A recent profile on Wolfe-Simon, published in The New York Times, apparently set the ball rolling for the paper’s retraction. Thorp told Nature, “We reached a point where the inquiries [about whether we’d retract the paper] continued, and we decided it was better to come up with a resolution that would, at least from our perspective, be the last word on this.”

Patricia Foster, a biologist and research ethicist at Indiana University, who noted that the study was still generating citations, told Scientific American, “My conclusion is that, yes, the paper should be retracted so that a statement of caution appears whenever it is accessed.” At the same time, she said the retraction notice should clarify that there has been no research misconduct in the work.

Arizona State University geochemist and study author Ariel Anbar told Scientific American that the explanation behind the move was “unbelievably misleading.” He added that the evidence for contamination in the original study was weak and should be adjudicated by scientists, not the journal.

Steven Benner, a chemist at the Foundation for Applied Molecular Evolution who joined the authors in the 2010 NASA press conference as a critic, agreed with Anbar. He told Scientific American that Science should not act as a “gatekeeper” by retracting a study that might be wrong but wasn’t fraudulent and that doing so carries its own threat to open scientific research.

Laxman echoed similar views. “This will help make the threads unravel even faster when public trust in science is almost zero.”