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Bioaccumulation and Chemical Modification of Tc by Soil Bacteria
Abstract
Bioaccumulation and chemical modification of pertechnetate (TcO4-) by aerobically and anaerobically grown soil bacteria and by pure cultures of sulfate-reducing bacteria (Desulfovibrio sp.) were studied to gain insight on the possible mechanisms by which bacteria can affect the solubility of Tc in soil. Aerobically grown bacteria had no apparent effect on TcO4-; they did not accumulate Tc nor modify its chemical form. Anaerobically grown bacteria exhibited high bioaccumulation and reduced TcO4-, enabling its association with organics of the growth medium. Reduction was a metabolic process and not merely the result of reducing conditions in the growth medium. Association of Tc with bacterial polysaccharides was observed only in cultures of anaerobic bacteria. Sulfate-reducing bacteria efficiently removed Tc from solution and promoted its association with organics. Up to 70% of the total Tc in the growth medium was bioaccumulated and/or precipitated. The remaining Tc in soluble form was entirely associated with organics. Pertechnetate was not reduced by the same mechanism as dissimilatory sulfate reduction, but rather by some reducing agent released in the growth medium. A calculation of the amount of Tc that could be associated with the bacterial biomass present in soil demonstrates that high concentration ratios in cultures do not necessarily imply that bioaccumulation is an important mechanism for long-term retention of Tc in soil.
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Although microbial metabolism was known to decrease the solubility of Tc from earlier studies, Lloyd and Macaskie were the first to unequivocally demonstrate direct enzymatic reduction of Tc(VII) by micro-organisms.
“Although microbial metabolism was known to decrease the solubility of Tc from earlier studies [129,130], Lloyd and Macaskie were the ¢rst to unequivocally demonstrate direct enzymatic reduction of Tc(VII) by micro-organisms [131].”
From Microbial reduction of metals and radionuclides (2003) · cites this paper as [129]
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Lovley, D. R. (1993) · Annual Review of Microbiology · doi:10.1146/annurev.mi.47.100193.001403 · Cited by 1,021
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“Henrot (13) showed that the addition of sulfate-reducing bacteria to mixed cultures of anaerobically grown soil bacteria increased Tc removal by more than an order of magnitude.”
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“The relative immobility of technetium in agricultural fields was first noticed by Henrot (1989), who proposed that microbial activity may be causing reduction with consequent sorption and precipitation in the soil.”
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“Henrot (6) showed that anaerobically (but not aerobically) grown mixed cultures of soil bacteria accumulated Tc and that addition of the sulfate-reducing bacteria Desulfovibrio vulgaris and Desulfovibrio gigas increased Tc removal by more than an order of magnitude.”
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“The relative immobility of technetium in agricultural fields was first noticed by Henrot (1989), who proposed that microbial activity may be causing reduction with consequent sorption and precipitation in the soil.”
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“Henrot (1989) was one of the first to suggest that technetium in soils is immobilized in the form of TcS2 or Tc2S7 due to biological activity.”
BackgroundAnaerobes into heavy metal: Dissimilatory metal reduction in anoxic environments
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“Aerobic soil microflora are unable to reduce or accumulate TcO 4 (Henrot, 1989).”
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“Sulphate reducing bacteria Desulfovibrio gigas and D.vulgarisare effective in converting Tc (VII) to insoluble forms (Henrot, 1989).”
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“has been described as an analogue of S O l - (Henrot 1989).”
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“These anionic species are more similar in chemistry and size to TcO- than Cl-' indeed TcO- has been described as an analogue of SO2 - (Henrot, 1989).”
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Metadata
- Authors
- Henrot, J.
- Affiliations
- University of Tennessee at Knoxville (US)
- Corresponding author
- Henrot, Jacqueline
- Venue
- Health Physics
- Published
- 1989-08
- Volume
- 57
- Issue
- 2
- Pages
- 239-245
- ISSN
- 0017-9078 (ISSN-L)
- OpenAlex
- W2080628565
- Cited by
- 83
- References
- 0
- Citations by year
- 2025: 1 · 2024: 1 · 2020: 1 · 2019: 2 · 2018: 2 · 2017: 2 · 2015: 2 · 2014: 1 · 2013: 2 · 2012: 2
- FWCI
- 1.84
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Health Physics (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Physical Sciences › Chemistry › Inorganic Chemistry › Radioactive element chemistry and processing
- Physical Sciences › Environmental Science › Pollution › Radioactive contamination and transfer
- Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Chromium effects and bioremediation
- Keywords
- pertechnetate, soil bacteria, sulfate-reducing bacteria, Desulfovibrio, anaerobic reduction, bacterial polysaccharides, dissimilatory sulfate reduction, radionuclide immobilization
- MeSH terms
- Bacteria, Polysaccharides, Bacterial, Soil Microbiology, Soil Pollutants, Soil Pollutants, Radioactive, Solubility, Sodium Pertechnetate Tc 99m
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