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Arsenic and New Life Do you look at the stars and wonder if anyone else is out there?

Of course… astronomers routinely discover new planets outside our galaxy.

Now imagine a watery world with a super high pH, salt content three times our oceans, and massive amounts of arsenic. Can't imagine anything living there.

But it's here on earth, in a place called Mono Lake in California. A team of scientists just reported finding a new bacterium there, called GFAJ-1. They say it's surviving using arsenic in place of phosphorus – an essential element of life.

The news caught our attention and many in the science community because, until now, every living thing we know uses the six basic elements: carbon, nitrogen, oxygen, hydrogen, sulfur, and phosphorus.

Phosphorus is in DNA, proteins, lipids, and ATP which provide our cells with energy. So, how did the Mono Lake bacterium find a way to replace phosphorus with arsenic?

Turns out – it may not have. Though this study had been reviewed before publication, once other scientists read it, they found the authors used inappropriate methods to gather the data and over-interpeted the results.

While I found that disappointing, it reinforced my faith in the science community, because we all require exceptional data for groundbreaking claims. This is one way in which science self-corrects and maintains its credibility.

The authors of the phosphorous study did prove that arsenic accumulated in these bacteria but not that arsenic had actually replaced phosphorous in DNA or RNA.

If it is true, what we thought was essential to sustain life, would have shifted. It could change how we search for life beyond Earth; lead to new methods for wastewater treatment; and many other possibilities.

For now, it's up to the authors of the original paper to provide unequivocal proof of their assertions with more research using appropriate methods.

We hope they do.


For more information…

The original paper published describing a bacterium that can utilize arsenic can be read at. Wolfe-Simon F., et al. 2010. A bacterium that can grow by using arsenic instead of phosphorus. Science. doi:10.1126/science.1197258 (2010).

The journal Nature provided a commentary about the research and findings in a commentary entitled "Arsenic-eating microbe may redefine chemistry of life". There is also a link to additional discussions highlighting the criticism the paper has gotten from scientists around the world. For more information…

An article that highlights the questions raised about the publication can be read at, Katsnelson, A. 2010. "Microbe gets toxic response". 468: 741. Here and more can be read here.

A very readable account of the discovery and some of the discussion about it can be read here.

And the aftermath is summarized here.