When NASA astrobiologist Felisa Wolfe-Simon released a study in December 2010 that described a bacterium that seemed to grow on arsenic and incorporate it into its DNA, researchers were at first amazed. Some, however, were skeptical, and tried to replicate Wolfe-Simon's work. University of British Columbia microbiologist Rosemary Redfield has posted a paper on ArXiv that refutes Wolfe-Simon's conclusions, reports ScienceInsider's Elizabeth Pennisi. "Redfield … has grown the bacterium in the presence of arsenic and found no evidence of its uptake in the microbe's genetic material," Pennisi says. Redfield says she doesn't plan to do anymore follow-up research at this point, and adds that the "burden of proof" is back on Wolfe-Simon and her colleagues to show "better data than they did in their paper."
Wolfe-Simon and her group tell ScienceInsider their work is just beginning, but they don't plan on commenting on Redfield's work until it has been peer-reviewed and published.