Newman, Dianne K. and Beveridge, Terry J. and Morel, Francois M. M. (1997) Precipitation of Arsenic Trisulfide by Desulfotomaculum auripigmentum. Applied and Environmental Microbiology, 63 (5). pp. 2022-2028. ISSN 0099-2240 http://resolver.caltech.edu/CaltechAUTHORS:NEWaem97
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A newly discovered bacterium, Desulfotomaculum auripigmentum, precipitates arsenic trisulfide (As(inf2)S(inf3)). Precipitation of As(inf2)S(inf3) by this organism results from its reduction of As(V) to As(III) and S(VI) to S(-II). At the As(III) concentration range of interest (0.1 to 1 mM), the stability of As(inf2)S(inf3) is highly sensitive to pH and [S(-II)]. Thus, the relative rates at which D. auripigmentum reduces As(V) and S(VI) are critical to its formation of As(inf2)S(inf3). Other As(V)- or S(VI)-reducing bacteria are unable to precipitate As(inf2)S(inf3) either due to their inability to reduce both As(V) and S(VI) or because they reduce S(VI) too rapidly. Electron microscopy of thin sections showed that the precipitate forms both intra- and extracellularly. Microbial As(inf2)S(inf3) formation nucleates precipitation of the mineral in the bulk milieu, whereas heat-killed cells alone do not serve as templates for its formation. Precipitation of As(inf2)S(inf3) by D. auripigmentum suggests that As(inf2)S(inf3) formation may be important in the biogeochemical cycle of arsenic.
|Additional Information:||Copyright © 1997, American Society for Microbiology Received 7 October 1996/Accepted 24 February 1997. This research was supported by the ONR and the EPA and made use of the MIT MRSEC Electron Microscopy Shared Experimental Facility supported by the NSF. D.K.N. was supported by a NDSEG fellowship sponsored by the Department of Defense. This work is largely indebted to Tony Garratt-Reed, whose expertise with the VG STEM made the mineral analysis done in this study possible and whose guidance made it rigorous. We are also grateful to S. Tay (MIT) and E. Seling (Harvard MCZ Laboratory) for help with the photography in Fig. 1, P. Reilly (Biological EM Facility, MIT) for assistance with thin-section preparations, P. Heaney (Princeton) for help with crystallography, and our friends for constructive criticism of earlier versions of the manuscript.|
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|Deposited On:||31 Jan 2006|
|Last Modified:||26 Dec 2012 08:45|
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