Response of bentonite microbial communities to stresses relevant to geodisposal of radioactive waste

Haynes, Haydn M.; Pearce, Carolyn I.; Boothman, Christopher; Lloyd, Jonathan R.

doi:10.1016/j.chemgeo.2018.10.004

Cited by 31 publications

(23 citation statements)

References 50 publications

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“…Although similar orders were detected from the same type of enrichment across all samples, cultures from each sample had unique microbial profiles at the ASV level (Figures S5, S6, and S7). Here, and in previous research, several of the most frequently detected ASVs from cultures were affiliated with the Bacillus and Clostridium genera (13,18). Dominant taxa detected in cultures were low in abundance or even absent in the 2 microbial profiles of the corresponding clay samples (Figure 4).…”

Section: Comparison Of Cultivation and Nucleic Acid Isolation Approachessupporting

confidence: 86%

“…In 2 previous research, Desulfosporosinus spp. were also frequently detected in microcosms and enrichment cultures from multiple types of bentonite clay (13,18,39). Although many studies suggest that SRB make up the largest group within the microbial communities of clays (11,12,43,44), and SRB were dominant in SRB enrichments here, microbial community profiles of initial clay DNA extracts were not dominated by SRB (Figure 6).…”

Section: Comparison Of Cultivation and Nucleic Acid Isolation Approachesmentioning

confidence: 99%

“…The copyright holder for this preprint (which this version posted July 13, 2021. ; https://doi.org/10.1101/2021.07. 13.452221 doi: bioRxiv preprint radionuclide transport, transformation of clay minerals, and gas production (6,7). One of the primary microbiological concerns relevant to long-term containment of nuclear waste is microbiologically influenced corrosion.…”

Section: Introductionmentioning

confidence: 99%

“…Such corrosion might occur as active microorganisms release metabolites that directly or indirectly cause metal corrosion (8,9). For example, sulfatereducing bacteria (SRB) generate hydrogen sulfide (H 2 S), which can be corrosive to metals such as copper and steel (8,(10)(11)(12)(13). Heterotrophic bacteria are also relevant for DGR safety assessments because fermentation-associated hydrogen gas (H 2 ) and acetate production may promote sulfate-reduction by SRB through increased electron donor availability (12,14).…”

Section: Introductionmentioning

confidence: 99%

“…are commonly reported in enrichment cultures of natural clay deposits or saturated and highly compacted clays (16,26,38-2 41), and have sometimes been reported in uncompacted as-received clay (18). Several ASVs associated with the genera Paracoccus and Thiobacillus, potentially capable of denitrification and sulfur oxidation respectively (8,10,42), were detected in as-received clays but not in enrichment cultures, although they have also previously been detected in clay enrichment cultures(13,26).…”

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confidence: 99%

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Fifteen shades of clay: distinct microbial community profiles obtained from bentonite samples by cultivation and direct nucleic acid extraction

Vachon

Engel

Beaver

et al. 2021

Preprint

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Characterizing the microbiology of swelling bentonite clays can help predict the long-term behaviour of deep geological repositories (DGRs), which are proposed as a solution for the management of used nuclear fuel worldwide. Such swelling clays represent an important component of several proposed engineered barrier system designs and, although cultivation-based assessments of bentonite clay are routinely conducted, direct nucleic acid detection from these materials has been difficult due to technical challenges. In this study, we generated direct comparisons of microbial abundance and diversity captured by cultivation and direct nucleic acid analyses using 15 reference bentonite clay samples. Regardless of clay starting material, the corresponding profiles from cultivation-based approaches were consistently associated with phylogenetically similar sulfate-reducing bacteria, denitrifiers, aerobic heterotrophs, and fermenters, demonstrating that any DGR-associated growth may be consistent, regardless of the specific bentonite clay starting material selected for its construction. Furthermore, dominant nucleic acid sequences in the as-received clay microbial profiles did not correspond with the bacteria that were enriched or isolated in culture. Few core taxa were shared among cultivation and direct nucleic acid analysis profiles, yet those in common were primarily affiliated with Streptomyces, Micrococcaceae, Bacillus, and Desulfosporosinus genera. These putative desiccation-resistant bacteria associated with diverse bentonite clay samples can serve as targets for experiments that evaluate microbial viability and growth within DGR-relevant conditions. Our data will be important for global nuclear waste management organizations, demonstrating that identifying appropriate design conditions with suitable clay swelling properties will prevent growth of the same subset of clay-associated bacteria, regardless of clay origin or processing conditions.

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Section: Comparison Of Cultivation and Nucleic Acid Isolation Approachessupporting

confidence: 86%

Section: Comparison Of Cultivation and Nucleic Acid Isolation Approachesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Fifteen shades of clay: distinct microbial community profiles obtained from bentonite samples by cultivation and direct nucleic acid extraction

Vachon

Engel

Beaver

et al. 2021

Preprint

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Extremophilic microbial metabolism and radioactive waste disposal

Butterworth,

Barton,

Lloyd

2023

Extremophiles

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Decades of nuclear activities have left a legacy of hazardous radioactive waste, which must be isolated from the biosphere for over 100,000 years. The preferred option for safe waste disposal is a deep subsurface geological disposal facility (GDF). Due to the very long geological timescales required, and the complexity of materials to be disposed of (including a wide range of nutrients and electron donors/acceptors) microbial activity will likely play a pivotal role in the safe operation of these mega-facilities. A GDF environment provides many metabolic challenges to microbes that may inhabit the facility, including high temperature, pressure, radiation, alkalinity, and salinity, depending on the specific disposal concept employed. However, as our understanding of the boundaries of life is continuously challenged and expanded by the discovery of novel extremophiles in Earth’s most inhospitable environments, it is becoming clear that microorganisms must be considered in GDF safety cases to ensure accurate predictions of long-term performance. This review explores extremophilic adaptations and how this knowledge can be applied to challenge our current assumptions on microbial activity in GDF environments. We conclude that regardless of concept, a GDF will consist of multiple extremes and it is of high importance to understand the limits of polyextremophiles under realistic environmental conditions.

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Dramatic loss of microbial viability in bentonite exposed to heat and gamma radiation: implications for deep geological repository

Bartak,

Šachlová,

Kašpar

et al. 2024

World J Microbiol Biotechnol

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Bentonite is an integral part of the engineered barrier system (EBS) in deep geological repositories (DGR) for nuclear waste, but its indigenous microorganisms may jeopardize long-term EBS integrity. To predict microbial activity in DGRs, it is essential to understand microbial reactions to the early hot phase of DGR evolution. Two bentonites (BCV and MX-80) with varied bentonite/water ratios and saturation levels (compacted to 1600 kg.m− 3 dry density/powder/suspension), were subjected to heat (90–150 °C) and irradiation (0.4 Gy.h− 1) in the long-term experiments (up to 18 months). Molecular-genetic, microscopic, and cultivation-based techniques assessed microbial survivability. Exposure to 90 °C and 150 °C notably diminished microbial viability, irrespective of bentonite form, with negligible impacts from irradiation or sample type compared to temperature. Bentonite powder samples exhibited microbial recovery after 90 °C heating for up to 6 months but not 12 months in most cases; exposure to 150 °C had an even stronger effect. Further long-term experiments at additional temperatures combined with the mathematical prediction of temperature evolution in DGR are recommended to validate the possible evolution and spatial distribution of microbially depleted zones in bentonite buffer around the waste canisters and refine predictions of microbial effects over time in the DGR.

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Response of bentonite microbial communities to stresses relevant to geodisposal of radioactive waste

Cited by 31 publications

References 50 publications

Fifteen shades of clay: distinct microbial community profiles obtained from bentonite samples by cultivation and direct nucleic acid extraction

Fifteen shades of clay: distinct microbial community profiles obtained from bentonite samples by cultivation and direct nucleic acid extraction

Extremophilic microbial metabolism and radioactive waste disposal

Dramatic loss of microbial viability in bentonite exposed to heat and gamma radiation: implications for deep geological repository

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