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Applied and Environmental Microbiology, April 2009, p. 2558-2565, Vol. 75, No. 8
0099-2240/09/$08.00+0     doi:10.1128/AEM.02440-07
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Microbial Mineral Weathering for Nutrient Acquisition Releases Arsenic

Brian J. Mailloux,^1* Ekaterina Alexandrova,¹ Alison R. Keimowitz,² Karen Wovkulich,³ Greg A. Freyer,⁴ Michael Herron,² John F. Stolz,⁵ Timothy C. Kenna,² Thomas Pichler,⁶ Matthew L. Polizzotto,⁷ Hailiang Dong,⁸ Michael Bishop,⁸ and Peter S. K. Knappett⁹

Environmental Science Department, Barnard College, New York, New York 10027,¹ Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964,² Department of Earth and Environmental Science, Columbia University, New York, New York 10027,³ Environmental Health Science, Columbia University, New York, New York 10032,⁴ Department of Biological Sciences, Duquesne University, Pittsburgh, Pennsylvania 15282,⁵ Department of Geology, University South Florida, Tampa, Florida 33620-5201,⁶ Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305,⁷ Department of Geology, Miami University, Oxford, Ohio 45056,⁸ Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, Tennessee 37996⁹

Received 29 October 2007/ Accepted 6 February 2009

Tens of millions of people in Southeast Asia drink groundwater contaminated with naturally occurring arsenic. How arsenic is released from the sediment into the water remains poorly understood. Here, we show in laboratory experiments that phosphate-limited cells of Burkholderia fungorum mobilize ancillary arsenic from apatite. We hypothesize that arsenic mobilization is a by-product of mineral weathering for nutrient acquisition. The released arsenic does not undergo a redox transformation but appears to be solubilized from the apatite mineral lattice during weathering. Analysis of apatite from the source area in the Himalayan basin indicates the presence of elevated levels of arsenic, with an average concentration of 210 mg/kg. The rate of arsenic release is independent of the initial dissolved arsenic concentration and occurs at phosphate levels observed in Bangladesh aquifers. We also demonstrate the presence of the microbial phenotype that releases arsenic from apatite in Bangladesh aquifer sediments and groundwater. These results suggest that microbial mineral weathering for nutrient acquisition could be an important mechanism for arsenic mobilization.

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* Corresponding author. Mailing address: Environmental Science Department, Barnard College, 404 Altschul Hall, 76 Claremont Ave., New York, NY 10027. Phone: (212) 854-7956. Fax: (212) 854-5760. E-mail: bmaillou{at}barnard.edu

Published ahead of print on 27 February 2009.

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Applied and Environmental Microbiology, April 2009, p. 2558-2565, Vol. 75, No. 8
0099-2240/09/$08.00+0     doi:10.1128/AEM.02440-07
Copyright © 2009, American Society for Microbiology. All Rights Reserved.