DOE ER63951-3 Final Report: An Integrated Assessment of Geochemical and Community Structure Determinants of Metal Reduction Rates in Subsurface Sediments
The objective of this research was to examine the importance of microbial community structure in influencing uranium reduction rates in subsurface sediments. If the redox state alone is the key to metal reduction, then any organisms that can utilize the oxygen and nitrate in the subsurface can change the geochemical conditions so metal reduction becomes an energetically favored reaction. Thus, community structure would not be critical in determining rates or extent of metal reduction unless community structure influenced the rate of change in redox. Alternatively, some microbes may directly catalyze metal reduction (e.g., specifically reduce U). In this case the composition of the community may be more important and specific types of electron donors may promote the production of communities that are more adept at U reduction. Our results helped determine if the type of electron donor or the preexisting community is important in the bioremediation of metal-contaminated environments subjected to biostimulation. In a series of experiments at the DOE FRC site in Oak Ridge we have consistently shown that all substrates promoted nitrate reduction, while glucose, ethanol, and acetate always promoted U reduction. Methanol only occasionally promoted extensive U reduction which is possibly due to community heterogeneity. There appeared to be limitations imposed on the community related to some substrates (e.g. methanol and pyruvate). Membrane lipid analyses (phospholipids and respiratory quinones) indicated different communities depending on electron donor used. Terminal restriction fragment length polymorphism and clone libraries indicated distinct differences among communities even in treatments that promoted U reduction. Thus, there was enough metabolic diversity to accommodate many different electron donors resulting in the U bioimmobilization.
- Research Organization:
- University of Tennessee, Knoxville, TN
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- FG02-05ER63951
- OSTI ID:
- 982379
- Report Number(s):
- DOE ER63951-3 Final Report; Project ID# 0010963; TRN: US1103399
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
58 GEOSCIENCES
59 BASIC BIOLOGICAL SCIENCES
ACETATES
BINDING ENERGY
BIOREMEDIATION
COMMUNITIES
ELECTRONS
ETHANOL
GLUCOSE
LIPIDS
MEMBRANES
METHANOL
NITRATES
OXYGEN
PHOSPHOLIPIDS
PRODUCTION
QUINONES
SEDIMENTS
SUBSTRATES
URANIUM
VALENCE
Uranium reduction microbial community structure phospholipids respiratory quinones