Tuesday 25 November, 2014

Arsenic-friendly bacteria discovery in Mono Lake refuted

Published On: Mon, Jul 9th, 2012 | Microbiology | By BioNews

Researchers have claimed that the finding by a young researcher in 2010 about bacteria in Mono Lake, Calif., was wrong, insisting instead that they were using phosphorus, a very common building block of living things, instead of arsenic compounds.

In 2010, a young researcher, Felisa Wolfe-Simon, published a paper in the journal Science, reporting that she and her colleagues had found bacteria in Mono Lake, Calif., that could be made to live on arsenic.

But now two papers have been published proving her wrong.

“We conclude that GFAJ-1 is an arsenate-resistant, but still a phosphate-dependent bacterium,” ABC News quoted Tobias Erb and several fellow microbiologists in Zurich as writing.

Wolfe-Simon’s paper drew international attention because it potentially broadened the definition of life as we know it, including life on other planets.

Living things, for all their complexity, are based on six elements – oxygen, carbon, hydrogen, nitrogen, phosphorus and sulphur. Arsenic has chemical similarities to phosphorus, but it’s toxic.

So the original Wolfe-Simon paper was explosive. But so was the response. Rosie Redfield of the University of British Columbia in Canada quickly answered with a blog post: “Basically, it doesn’t present ANY convincing evidence that arsenic has been incorporated into DNA (or any other biological molecule).”

Redfield was a co-author of one of the new papers. She and colleagues at Princeton University analyzed the work of Wolfe-Simon’s team, and found it wanting.

“Mass spectrometry showed that this DNA contains only trace amounts of free arsenate and no detectable covalently bound arsenate,” they concluded.

Wolfe-Simon later wrote an email to ABC News.

“There is nothing in the data of these new papers that contradicts our published data, which is also consistent with our current results. Our work continues to build upon our finding of extreme resistance to arsenate toxicity and the unexpected uptake of arsenate in the GFAJ-1 cells in the absence of added phosphate,” she wrote.

The new studies have been published in Science.

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