The Arsenic Bug: Steerike Two!

Back in December 2010 we had a report of a microbe isolated from Mono Lake that allegedly used arsenate in place of phosphate when grown in low phosphate media, and incorporated arsenic in place of phosphate in its DNA. Doubts about the article grew up instantly, and rightfully so, as outstanding claims require outstanding evidence, and this evidence fell apart when looked at skeptically.  The result of that study are scheduled to be published in Science later this month.

By January of 2012, a research group had refuted the most outlandish claim, that arsenic was used by the bacterium in the structure of DNA (or whatever the As equivalent of DNA would be called).

Now a second group has shown that the bacterium named (GFAJ-1; for Give Felisa a Job) could grow on the very low amount of phosphorus in the medium, but could not grow in it's absence:  Two studies show 'weird life' microbe can't live on arsenic:

The other study published today, with ETH Zurich's Tobias Erb as lead author, takes a wide-angle view of GFAJ-1, using mass spectrometry and other tools to trace the bacteria's chemical processes on the molecular level. They found that the microbes could grow with even less phosphorus than the tiny amount that was provided in the experiments by Wolfe-Simon and her colleagues. But when the phosphorus concentration was reduced to nearly nothing (less than 0.3 micromolar), no growth was observed.

This really is science in all it's working glory.  A young scientist (Felisa Wolfe-Simon, the lead author of the original article, was a young post-doc with a sexy story (well, as sexy as microbiology can get), and some shaky evidence.  She got it published; it stimulated a lot of interest and criticism and it got tested and checked.  It failed twice. She's not the first, and will not be the last scientist to have her/his/its pet theory disproved.

I do feel a little sorry for Felisa; having such a well publicized error cannot be too good for her job prospects, and it's tough world out there: U.S. pushes for more scientists, but the jobs aren’t there.