Arsenic-resistant bacterium still needs phosphate for growth

A paper co-authored by JAAS Editorial Board Chair, Detlef Günther has been published in Science and contributes to an ongoing discussion on the role of arsenic in the bacterial isolate GFAJ-1.

In December 2010, Felisa Wolfe-Simon and colleagues published a paper, also in Science, which proposed that GFAJ-1 could substitute small amounts of phosphorus in its DNA with arsenic. This claim would have significant implications for our understanding of life, since all known forms of life on Earth typically use oxygen, carbon, hydrogen, phosphorus and sulfur.

This new work from Detlef and fellow researchers at ETH Zürich shows that GFAJ-1 is able to grow at low phosphate concentrations even under high arsenate concentrations, but cannot grow in phosphorus-depleted, arsenate-containing medium. They combined physiological experiments with ICP-OES and ICP-MS to provide evidence that whilst GFAJ-1 is highly resistant to arsenate, but still requires phosphate for growth. The authors say that the molecular basis for arsenate resistance in GFAJ-1 could be the subject of further investigations.

GFAJ-1 Is an Arsenate-Resistant, Phosphate-Dependent Organism
Tobias J. Erb, Patrick Kiefer, Bodo Hattendorf, Detlef Günther, Julia A. Vorholt
DOI: 10.1126/science.1218455

Also published in Science is a paper from Rosie Redfield and colleagues at Princeton University, which supports the conclusions from the ETH group:

Absence of Detectable Arsenate in DNA from Arsenate-Grown GFAJ-1 Cells
Marshall Louis Reaves, Sunita Sinha, Joshua D. Rabinowitz, Leonid Kruglyak, Rosemary J. Redfield
DOI: 10.1126/science.1219861

Though not quite as controversial, take a look at some recent content in JAAS on arsenic:

Technical Note: Rapid screening of arsenic species in urine from exposed human by inductively coupled plasma mass spectrometry with germanium as internal standard
A. Castillo,  C. Boix,  N. Fabregat,  A. F. Roig-Navarro and J. A. Rodríguez-Castrillón
J. Anal. At. Spectrom., 2012, 27, 354-358
DOI: 10.1039/C1JA10289C

An interlaboratory study of arsenic speciation analysis of whole blood
Kanna Ito,  Walter Goessler,  Hakan Gürleyük,  Brian Wels,  Christopher D. Palmer,  Mary Frances Verostek and Patrick J. Parsons
J. Anal. At. Spectrom., 2011, 26, 1740-1745
DOI: 10.1039/C1JA10040H

Intracellular, time-resolved speciation and quantification of arsenic compounds in human urothelial and hepatoma cells
Joerg Hippler,  Ricarda Zdrenka,  Robin A. D. Reichel,  Daniel G. Weber,  Peter Rozynek,  Georg Johnen,  Elke Dopp and Alfred V. Hirner
J. Anal. At. Spectrom., 2011, 26, 2396-2403
DOI: 10.1039/C1JA10150A

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