Methanogenic and sulphate-reducing microbial communities in deep groundwater of crystalline rock fractures in Olkiluoto, Finland

Mari Nyyssönen, Malin Bomberg, Anu Kapanen, Aura Nousiainen, Petteri Pitkänen, Merja Itävaara

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

The long-term safety of final disposal of spent nuclear fuel in the deep geosphere is dependent on stability of biogeochemical conditions at the disposal site. Microbial processes, such as sulphate reduction and methanogenesis, may have profound effects on site biogeochemistry. In this study, sulphate-reducing bacteria and methane-producing archaea were investigated at depths ranging from 68 to 545 m in crystalline rock fractures at an intended spent nuclear fuel disposal site in Olkiluoto, Finland. Denaturing gradient gel electrophoresis detected diverse sulphate-reducing bacterial communities in all samples. Although the number of dsrB gene copies was below 103 copies ml−1 in all analyzed samples according to real-time quantitative PCR, their abundance was highest in samples that had the highest sulphate concentrations. Several distinct mcrA gene fragments were also recovered from most of the analyzed samples by cloning, although the number of methanogens was lower than that of sulphate-reducing bacteria when measured by mcrA-targeted quantitative PCR. The detected gene fragments were most closely related to sequences obtained from aquatic and deep subsurface environments. Results imply that sulphate reduction, methanogenesis, and anaerobic methane oxidation may all take place in the Olkiluoto deep geobiosphere.
Original languageEnglish
Pages (from-to)863-878
Number of pages15
JournalGeomicrobiology Journal
Volume29
Issue number10
DOIs
Publication statusPublished - 2012
MoE publication typeA1 Journal article-refereed

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Crystalline rocks
Groundwater
crystalline rock
Finland
Sulfates
microbial community
sulfate
groundwater
methanogenesis
sulfate-reducing bacterium
gene
Genes
methane
Spent fuels
Methane
Nuclear fuels
take-all
Bacteria
biogeochemistry
Biogeochemistry

Cite this

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title = "Methanogenic and sulphate-reducing microbial communities in deep groundwater of crystalline rock fractures in Olkiluoto, Finland",
abstract = "The long-term safety of final disposal of spent nuclear fuel in the deep geosphere is dependent on stability of biogeochemical conditions at the disposal site. Microbial processes, such as sulphate reduction and methanogenesis, may have profound effects on site biogeochemistry. In this study, sulphate-reducing bacteria and methane-producing archaea were investigated at depths ranging from 68 to 545 m in crystalline rock fractures at an intended spent nuclear fuel disposal site in Olkiluoto, Finland. Denaturing gradient gel electrophoresis detected diverse sulphate-reducing bacterial communities in all samples. Although the number of dsrB gene copies was below 103 copies ml−1 in all analyzed samples according to real-time quantitative PCR, their abundance was highest in samples that had the highest sulphate concentrations. Several distinct mcrA gene fragments were also recovered from most of the analyzed samples by cloning, although the number of methanogens was lower than that of sulphate-reducing bacteria when measured by mcrA-targeted quantitative PCR. The detected gene fragments were most closely related to sequences obtained from aquatic and deep subsurface environments. Results imply that sulphate reduction, methanogenesis, and anaerobic methane oxidation may all take place in the Olkiluoto deep geobiosphere.",
author = "Mari Nyyss{\"o}nen and Malin Bomberg and Anu Kapanen and Aura Nousiainen and Petteri Pitk{\"a}nen and Merja It{\"a}vaara",
year = "2012",
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language = "English",
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pages = "863--878",
journal = "Geomicrobiology Journal",
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Methanogenic and sulphate-reducing microbial communities in deep groundwater of crystalline rock fractures in Olkiluoto, Finland. / Nyyssönen, Mari; Bomberg, Malin; Kapanen, Anu; Nousiainen, Aura; Pitkänen, Petteri; Itävaara, Merja.

In: Geomicrobiology Journal, Vol. 29, No. 10, 2012, p. 863-878.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Methanogenic and sulphate-reducing microbial communities in deep groundwater of crystalline rock fractures in Olkiluoto, Finland

AU - Nyyssönen, Mari

AU - Bomberg, Malin

AU - Kapanen, Anu

AU - Nousiainen, Aura

AU - Pitkänen, Petteri

AU - Itävaara, Merja

PY - 2012

Y1 - 2012

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AB - The long-term safety of final disposal of spent nuclear fuel in the deep geosphere is dependent on stability of biogeochemical conditions at the disposal site. Microbial processes, such as sulphate reduction and methanogenesis, may have profound effects on site biogeochemistry. In this study, sulphate-reducing bacteria and methane-producing archaea were investigated at depths ranging from 68 to 545 m in crystalline rock fractures at an intended spent nuclear fuel disposal site in Olkiluoto, Finland. Denaturing gradient gel electrophoresis detected diverse sulphate-reducing bacterial communities in all samples. Although the number of dsrB gene copies was below 103 copies ml−1 in all analyzed samples according to real-time quantitative PCR, their abundance was highest in samples that had the highest sulphate concentrations. Several distinct mcrA gene fragments were also recovered from most of the analyzed samples by cloning, although the number of methanogens was lower than that of sulphate-reducing bacteria when measured by mcrA-targeted quantitative PCR. The detected gene fragments were most closely related to sequences obtained from aquatic and deep subsurface environments. Results imply that sulphate reduction, methanogenesis, and anaerobic methane oxidation may all take place in the Olkiluoto deep geobiosphere.

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