Arsenic and Bacteria

The blogosphere is not happy with the recent announcement by NASA of bacteria that are able to "thrive and reproduce using the toxic chemical arsenic." [NASA-Funded Research Discovers Life Built With Toxic Chemical]

This finding of an alternative biochemistry makeup will alter biology textbooks and expand the scope of the search for life beyond Earth. The research is published in this week's edition of Science Express.

I read the paper (Wolfe-Simon et al., 2010) and I can assure you that nothing in that paper is going into my biochemistry textbook. I predict that a year from now we'll have forgotten about this discovery. I'm not even sure it's going to be confirmed but, if it is, the result is pretty trivial.

For a start, even the title of the paper is misleading. The title says "A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus" but all of the data show that there was phosphorus in the media and that the bacteria used it for growth and reproduction. This selected strain of bacteria incorporated more arsenic than non-selected species but it by no means did it replace all phosphate with arsenic. Only a few percent (at most) of the phosphorus atoms in DNA, for example, were replaced by arsenic.

The purpose of this posting it to alert you to a fantastic article by microbiologist Rosie Redfield at the University of British Columbia. I strongly urge that everyone read her take-down of the science paper [Arsenic-associated bacteria (NASA's claims)]. The problem is not just that a bad paper was published in Science—it's that the paper was so heavily promoted in the media. We've got to do better when it comes to educating the general public about science.

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Wolfe-Simon, F., Blum, J.S., Kulp, T.R., Gordon, G.W., Hoeft, S.E., Pett-Ridge, J., Stolz, J.F., Webb, S.M., Weber, P.K., Davies, P.C.W., Anbar, A.D., and Oremland, R.S. (2010) A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus. Science Published Online 2 December 2010 [DOI: 10.1126/science.1197258]