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Hold the Arsenic

February 03, 2012

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.


At the time of its

Submitted by S. Pelech - Kinexus on Fri, 02/03/2012 - 14:39.

At the time of its announcement, I provided a summary of many problematic aspects of the Wolfe-Simon NASA study in a previous commentary in GenomeWeb's The Daily Scan. It can be viewed at the url:

http://www.genomeweb.com/blog/arsenic-yes-please

I agree with my University of British Columbia colleague Dr. Redfield that the far reaching conclusions of the Wolfe-Simon et al. paper are not sufficiently supported by the data.

Perhaps the quantity of

Submitted by kph on Fri, 02/03/2012 - 15:36.

Perhaps the quantity of phosphate in Redfield's experiment was too high. If phosphate is available then the bacteria will incorporate phosphate into their DNA. They prefer phosphate to arsenate.

To claim that the bacteria are incapable of incorporating arsenate, the experiment should be set up so that they have no choice. Either they incorporate arsenate or they don't replicate their DNA.

Redfield's observation that the bacteria grew yet didn't incorporate arsenate implies that they did have a choice. And they chose phosphate which is no surprise.

This work does not refute Wolfe-Simon's findings.