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Applied and Environmental Microbiology, May 2008, p. 3159-3170, Vol. 74, No. 10
0099-2240/08/$08.00+0     doi:10.1128/AEM.02881-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Functional Diversity and Electron Donor Dependence of Microbial Populations Capable of U(VI) Reduction in Radionuclide-Contaminated Subsurface Sediments{triangledown}

Denise M. Akob,1 Heath J. Mills,1 Thomas M. Gihring,1 Lee Kerkhof,2 Joseph W. Stucki,3 Alexandre S. Anastácio,3 Kuk-Jeong Chin,4 Kirsten Küsel,5 Anthony V. Palumbo,6 David B. Watson,6 and Joel E. Kostka1*

Florida State University, Tallahassee, Florida 32306,1 Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey 08901,2 Department of Natural Resources and Environmental Sciences, University of Illinois, Urbana, Illinois 61801,3 Department of Biology, Georgia State University, Atlanta, Georgia 30303,4 Institute of Ecology, Friedrich Schiller University Jena, 07743 Jena, Germany,5 Oak Ridge National Laboratory, Oak Ridge, Tennessee 378316

Received 20 December 2007/ Accepted 19 March 2008

In order to elucidate the potential mechanisms of U(VI) reduction for the optimization of bioremediation strategies, the structure-function relationships of microbial communities were investigated in microcosms of subsurface materials cocontaminated with radionuclides and nitrate. A polyphasic approach was used to assess the functional diversity of microbial populations likely to catalyze electron flow under conditions proposed for in situ uranium bioremediation. The addition of ethanol and glucose as supplemental electron donors stimulated microbial nitrate and Fe(III) reduction as the predominant terminal electron-accepting processes (TEAPs). U(VI), Fe(III), and sulfate reduction overlapped in the glucose treatment, whereas U(VI) reduction was concurrent with sulfate reduction but preceded Fe(III) reduction in the ethanol treatments. Phyllosilicate clays were shown to be the major source of Fe(III) for microbial respiration by using variable-temperature Mössbauer spectroscopy. Nitrate- and Fe(III)-reducing bacteria (FeRB) were abundant throughout the shifts in TEAPs observed in biostimulated microcosms and were affiliated with the genera Geobacter, Tolumonas, Clostridium, Arthrobacter, Dechloromonas, and Pseudomonas. Up to two orders of magnitude higher counts of FeRB and enhanced U(VI) removal were observed in ethanol-amended treatments compared to the results in glucose-amended treatments. Quantification of citrate synthase (gltA) levels demonstrated a stimulation of Geobacteraceae activity during metal reduction in carbon-amended microcosms, with the highest expression observed in the glucose treatment. Phylogenetic analysis indicated that the active FeRB share high sequence identity with Geobacteraceae members cultivated from contaminated subsurface environments. Our results show that the functional diversity of populations capable of U(VI) reduction is dependent upon the choice of electron donor.

* Corresponding author. Mailing address: Department of Oceanography, Florida State University, FSU Collins Research Laboratory, 255 Atomic Way, Bldg. 42, Tallahassee, FL 32306-4470. Phone: (850) 644-5719. Fax: (850) 644-2581. E-mail: jkostka{at}ocean.fsu.edu

{triangledown} Published ahead of print on 31 March 2008.

Applied and Environmental Microbiology, May 2008, p. 3159-3170, Vol. 74, No. 10
0099-2240/08/$08.00+0     doi:10.1128/AEM.02881-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Shelobolina, E. S., Konishi, H., Xu, H., Roden, E. E. (2009). U(VI) Sequestration in Hydroxyapatite Produced by Microbial Glycerol 3-Phosphate Metabolism. Appl. Environ. Microbiol. 75: 5773-5778 [Abstract] [Full Text]  


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