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Correlative Cryogenic Spectromicroscopy to Investigate Selenium Bioreduction Products

Fakra, Sirine C. and Luef, Birgit and Castelle, Cindy J. and Mullin, Sean W. and Williams, Kenneth H. and Marcus, Matthew A. and Schichnes, Denise and Banfield, Jillian F. (2018) Correlative Cryogenic Spectromicroscopy to Investigate Selenium Bioreduction Products. Environmental Science and Technology, 52 (2). pp. 503-512. ISSN 0013-936X. doi:10.1021/acs.est.5b01409.

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Accurate mapping of the composition and structure of minerals and associated biological materials is critical in geomicrobiology and environmental research. Here, we have developed an apparatus that allows the correlation of cryogenic transmission electron microscopy (cryo-TEM) and synchrotron hard X-ray microprobe (SHXM) data sets to precisely determine the distribution, valence state, and structure of selenium in biofilms sampled from a contaminated aquifer near Rifle, CO. Results were replicated in the laboratory via anaerobic selenate-reducing enrichment cultures. 16S rRNA analyses of field-derived biofilm indicated the dominance of Betaproteobacteria from the Comamonadaceae family and uncultivated members of the Simplicispira genus. The major product in field and culture-derived biofilms is ∼25–300 nm red amorphous Se^0 aggregates of colloidal nanoparticles. Correlative analyses of the cultures provided direct evidence for the microbial dissimilatory reduction of Se(VI) to Se(IV) to Se^0. Extended X-ray absorption fine-structure spectroscopy showed red amorphous Se^0 with a first shell Se–Se interatomic distance of 2.339 ± 0.003 Å. Complementary scanning transmission X-ray microscopy revealed that these aggregates are strongly associated with a protein-rich biofilm matrix. These findings have important implications for predicting the stability and mobility of Se bioremediation products and understanding of Se biogeochemical cycling. The approach, involving the correlation of cryo-SHXM and cryo-TEM data sets from the same specimen area, is broadly applicable to biological and environmental samples.

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Mullin, Sean W.0000-0002-6225-3279
Additional Information:© 2015 American Chemical Society. Received: March 19, 2015; Revised: September 7, 2015; Accepted: September 15, 2015; Published: September 15, 2015. This material is partially based on work supported through the Lawrence Berkeley National Laboratory’s Sustainable Systems Scientific Focus Area. The U.S. Department of Energy Office of Science and the Office of Biological and Environmental Research funded the work under contracts DE-SC0004733 and DE-AC02-05CH11231. Part of the equipment was funded by the LBL EFRC Center for Nanoscale Control of Geologic CO2. We thank Paul Baker at Instec Inc. for his help with the microprobe cryostage, Sue Spaulding for lab support, Tolek Tylizscack for support at ALS beamline 11.0.2, and Mary Gilles and Steve Kelly for sharing their ESEM. We are grateful to D. Strawn, A. Ryser, E.A.H. Pilon-Smits, and J.L. Freeman for sharing their selenium standard spectra. The Advanced Light Source is supported by the Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy contract no. DE-AC02-05CH11231. The authors declare no competing financial interest.
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0004733
Department of Energy (DOE)DE-AC02-05CH11231
Issue or Number:2
Record Number:CaltechAUTHORS:20180207-110228013
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Official Citation:Correlative Cryogenic Spectromicroscopy to Investigate Selenium Bioreduction Products. Sirine C. Fakra, Birgit Luef, Cindy J. Castelle, Sean W. Mullin, Kenneth H. Williams, Matthew A. Marcus, Denise Schichnes, and Jillian F. Banfield. Environmental Science & Technology 2018 52 (2), 503-512 DOI: 10.1021/acs.est.5b01409
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84715
Deposited By: Tony Diaz
Deposited On:08 Feb 2018 00:14
Last Modified:15 Nov 2021 20:22

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