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GFAJ-1 Is an Arsenate-Resistant, Phosphate-Dependent Organism

Science  08 Jul 2012:

DOI: 10.1126/science.1218455

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Abstract

The bacterial isolate GFAJ-1 has recently been proposed to substitute arsenic for phosphorus to sustain growth. We have shown that GFAJ-1 is able to grow at low phosphate concentrations (1.7 μM), even in the presence of high concentrations of arsenate (40 mM), but lacked the ability to grow in phosphorus-depleted (<0.3 μM), arsenate-containing medium. High-resolution mass spectrometry analyses revealed that phosphorylated central metabolites and phosphorylated nucleic acids predominated. A few arsenylated compounds, including C6 sugar arsenates, were detected in extracts of GFAJ-1, when GFAJ-1 was incubated with AsO43-, but further experiments showed that they formed abiotically. Inductively coupled plasma mass spectrometry confirmed the presence of phosphorus and the absence of arsenic in nucleic acid extracts. Taken together, we conclude that GFAJ-1 is an arsenate-resistant, but still a phosphate-dependent bacterium.

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