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Title: [Cobalt(III)-EDTA]- Reduction by Thermophilic Methanogen Methanothermobacter Thermautotrophicus

Cobalt is a metal contaminant at high temperature radioactive waste disposal sites. In previous studies have largely focused on mesophilic microorganisms to remediate cobalt, despite the presence of thermophilic microorganisms at such sites. In this study,Methanothermobacter thermautotrophicus, a thermophilic methanogen, was used to reduce Co(III) in the form of [Co(III)–EDTA]-. Bioreduction experiments were conducted in a growth medium with H2/CO2 as a growth substrate at initial Co(III) concentrations of 1, 2, 4, 7, and 10 mM. At low Co(III) concentrations (< 4 mM), a complete reduction was observed within a week. Wet chemistry, X-ray absorption near-edge structure (XANES) and electron paramagnetic resonance (EPR) analyses were all consistent in revealing the reduction kinetics. But, at higher concentrations (7 and 10 mM) the reduction extents only reached 69.8% and 48.5%, respectively, likely due to the toxic effect of Co(III) to the methanogen cells as evidenced by a decrease in total cellular protein at these Co(III) concentrations. Methanogenesis was inhibited by Co(III) bioreduction, possibly due to impaired cell growth and electron diversion from CO2 to Co(III). Overall, our results demonstrated the ability of M. thermautotrophicus to reduce Co(III) to Co(II) and its potential application for remediating 60Co contaminant at high temperature subsurface radioactivemore » waste disposal sites.« less
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [1] ;  [1]
  1. Miami Univ., Oxford, OH (United States)
  2. Miami Univ., Oxford, OH (United States); China Univ. of Geosciences, Beijing (China)
  3. Miami Univ., Oxford, OH (United States); China Univ. of Geosciences, Wuhan (China)
Publication Date:
OSTI Identifier:
1228869
Report Number(s):
BNL--110944-2015-JA
Journal ID: ISSN 0009-2541
DOE Contract Number:
SC00112704
Resource Type:
Journal Article
Resource Relation:
Journal Name: Chemical Geology; Journal Volume: 411
Publisher:
Elsevier
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 36 MATERIALS SCIENCE cobalt; methanogen; bioreduction; methanogenesis; XANES; EPR