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Title: Promoting Uranium Immobilization by the Activities of Microbial Phosphatases

Abstract

The overall goal of this project is to examine the role of nonspecific phosphohydrolases present in naturally occurring subsurface microorganisms for the purpose of promoting the immobilization of radionuclides through the production of uranium [U(VI)] phosphate precipitates. Specifically, we hypothesize that the precipitation of U(VI) phosphate minerals may be promoted through the microbial release and/or accumulation of PO{sub 4}{sup 3-}. During this phase of the project we have been conducting assays to determine the effects of pH, inorganic anions and organic ligands on U(VI) mineral formation and precipitation when FRC bacterial isolates were grown in simulated groundwater medium. The molecular characterization of FRC isolates has also been undertaken during this phase of the project. Analysis of a subset of gram-positive FRC isolates cultured from FRC soils (Areas 1, 2 and 3) and background sediments have indicated a higher percentage of isolates exhibiting phosphatase phenotypes (i.e., in particular those surmised to be PO{sub 4}{sup 3-}-irrepressible) relative to isolates from the reference site. A high percentage of strains that exhibited such putatively PO{sub 4}{sup 3-}-irrepressible phosphatase phenotypes were also resistant to the heavy metals lead and cadmium. Previous work on FRC strains, including Arthrobacter, Bacillus and Rahnella spp., has demonstrated differences inmore » tolerance to U(VI) toxicity (200 {micro}M) in the absence of organophosphate substrates. For example, Arthrobacter spp. exhibited the greatest tolerance to U(VI) while the Rahnella spp. have been shown to facilitate the precipitation of U(VI) from solution and the Bacillus spp. demonstrate the greatest sensitivity to acidic conditions and high concentrations of U(VI). PCR-based detection of FRC strains are being conducted to determine if non-specific acid phosphatases of the known molecular classes [i.e., classes A, B and C] are present in these FRC isolates. Additionally, these amplified phosphatases are being analyzed to determine whether or not there is evidence for the horizontal transfer of such genes amongst subsurface microbial populations. Microbially precipitated U(VI) phosphate minerals will be further analyzed via capillary electrophoresis and extended x-ray absorption fine structure spectroscopy to determine uranium speciation.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Georgia Institute of Technology, Atlanta, GA
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
894634
Report Number(s):
CONF-ERSP2006-47
TRN: US0700204
Resource Type:
Conference
Resource Relation:
Conference: Annual Environmental Remediation Sciences Program PI Meeting, April 3-5, 2006, Warrenton, VA
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; 38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; 54 ENVIRONMENTAL SCIENCES; ABSORPTION; ACID PHOSPHATASE; ANIONS; BACILLUS; CADMIUM; ELECTROPHORESIS; FINE STRUCTURE; GENES; MICROORGANISMS; PHOSPHATASES; PHOSPHATE MINERALS; PHOSPHATES; PHOSPHOHYDROLASES; RADIOISOTOPES; SEDIMENTS; SOILS; SPECTROSCOPY; STRAINS; SUBSTRATES; TOLERANCE; TOXICITY; URANIUM

Citation Formats

Martinez, Robert J, Beazley, Melanie J, Wilson, Jarad J, Taillefert, Martial, and Sobecky, Patricia A. Promoting Uranium Immobilization by the Activities of Microbial Phosphatases. United States: N. p., 2005. Web.
Martinez, Robert J, Beazley, Melanie J, Wilson, Jarad J, Taillefert, Martial, & Sobecky, Patricia A. Promoting Uranium Immobilization by the Activities of Microbial Phosphatases. United States.
Martinez, Robert J, Beazley, Melanie J, Wilson, Jarad J, Taillefert, Martial, and Sobecky, Patricia A. Tue . "Promoting Uranium Immobilization by the Activities of Microbial Phosphatases". United States. https://www.osti.gov/servlets/purl/894634.
@article{osti_894634,
title = {Promoting Uranium Immobilization by the Activities of Microbial Phosphatases},
author = {Martinez, Robert J and Beazley, Melanie J and Wilson, Jarad J and Taillefert, Martial and Sobecky, Patricia A},
abstractNote = {The overall goal of this project is to examine the role of nonspecific phosphohydrolases present in naturally occurring subsurface microorganisms for the purpose of promoting the immobilization of radionuclides through the production of uranium [U(VI)] phosphate precipitates. Specifically, we hypothesize that the precipitation of U(VI) phosphate minerals may be promoted through the microbial release and/or accumulation of PO{sub 4}{sup 3-}. During this phase of the project we have been conducting assays to determine the effects of pH, inorganic anions and organic ligands on U(VI) mineral formation and precipitation when FRC bacterial isolates were grown in simulated groundwater medium. The molecular characterization of FRC isolates has also been undertaken during this phase of the project. Analysis of a subset of gram-positive FRC isolates cultured from FRC soils (Areas 1, 2 and 3) and background sediments have indicated a higher percentage of isolates exhibiting phosphatase phenotypes (i.e., in particular those surmised to be PO{sub 4}{sup 3-}-irrepressible) relative to isolates from the reference site. A high percentage of strains that exhibited such putatively PO{sub 4}{sup 3-}-irrepressible phosphatase phenotypes were also resistant to the heavy metals lead and cadmium. Previous work on FRC strains, including Arthrobacter, Bacillus and Rahnella spp., has demonstrated differences in tolerance to U(VI) toxicity (200 {micro}M) in the absence of organophosphate substrates. For example, Arthrobacter spp. exhibited the greatest tolerance to U(VI) while the Rahnella spp. have been shown to facilitate the precipitation of U(VI) from solution and the Bacillus spp. demonstrate the greatest sensitivity to acidic conditions and high concentrations of U(VI). PCR-based detection of FRC strains are being conducted to determine if non-specific acid phosphatases of the known molecular classes [i.e., classes A, B and C] are present in these FRC isolates. Additionally, these amplified phosphatases are being analyzed to determine whether or not there is evidence for the horizontal transfer of such genes amongst subsurface microbial populations. Microbially precipitated U(VI) phosphate minerals will be further analyzed via capillary electrophoresis and extended x-ray absorption fine structure spectroscopy to determine uranium speciation.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2005},
month = {4}
}

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