An indigenous iron-reducing microbial community from MX80 bentonite - A study in the framework of nuclear waste disposal

Gilmour, Katie; Davie, CT; Gray, Neil

doi:10.1016/j.clay.2021.106039

Cited by 18 publications

(21 citation statements)

References 56 publications

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“…, Bacillaceae, Peptostreptococcaceae, Clostridiaceae and Peptococcaceae ) that need these enzymatic systems for normal sporulation/germination processes ( Bobek et al., 2014 ). Such an enrichment is of no coincidence since spore-formers have repeatedly been observed to predominate among cultivable bacteria in bentonites ( Chi Fru and Athar, 2008 ; Gilmour et al., 2021 ; Grigoryan et al., 2020 ; Haynes et al., 2018 ; Jalique et al., 2016 ; Matschiavelli et al., 2019 ; Podlech et al., 2021 ). The anoxic clay microcosms were highly likely driven primarily by sulfate and hydrogen, and the sulfur metabolism fell in the top 30–35% of the most significant contributor to metabolic processes.…”

Section: Discussionmentioning

confidence: 99%

“…An increased share of enzymes related to intracellular accumulation of the carbohydrate phosphate esters (phosphotransferase system), fructose and mannose metabolism, sporulation and peptidases in the sequenced 16S rRNA gene libraries from H 2 -fed microcosms with MX-80 Batch 1 clay, perhaps was due to enrichment of these incubations with spore-forming bacteria (e.g., Bacillaceae, Peptostreptococcaceae, Clostridiaceae and Peptococcaceae) that need these enzymatic systems for normal sporulation/germination processes (Bobek et al, 2014). Such an enrichment is of no coincidence since spore-formers have repeatedly been observed to predominate among cultivable bacteria in bentonites (Chi Fru and Athar, 2008;Gilmour et al, 2021;Grigoryan et al, 2020;Haynes et al, 2018;Jalique et al, 2016;Matschiavelli et al, 2019;Podlech et al, 2021). The anoxic clay microcosms were highly likely driven primarily by sulfate and hydrogen, and the sulfur metabolism fell in the top 30-35% of the most significant contributor to metabolic processes.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, microbiological insights derived from uncompacted clay microcosms can, to some extent, be representative of a DGR environment as well, and offer some advantage in terms of extracting nucleic acids from microbes that have managed to increase in number due to lack of typical constraints seen under high swelling pressure, low pore space and low water availability in highly compacted clay (Jalique et al, 2016). Others found bacteria of the Desulfuromonas-Pelobacter-Geobacter group, along with some bacteria within the Desulfovibrionaceae, were detected using either DGGE (Grigoryan et al, 2018;Svensson et al, 2011) or high throughput sequencing in clay microcosms or enrichments (Gilmour et al, 2021;Grigoryan et al, 2018;Haynes et al, 2018, and the current study) and in biofilms associated with compacted bentonites (Hallbeck et al, 2017). It has been speculated recently that these bacteria, may be capable of harvesting electrons for sulfooxyanion reduction directly from insoluble minerals and metals using several extracellular multi-heme cytochromes (Deng et al, 2018), and therefore causing their corrosion.…”

Section: Discussionmentioning

confidence: 99%

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Prediction of bacterial functional diversity in clay microcosms

Grigoryan

Jalique

Stroes-Gascoyne

et al. 2021

Heliyon

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Microorganisms in clay barriers could affect the long-term performance of waste containers in future deep geological repositories (DGR) for used nuclear fuel through production of corrosive metabolites (e.g., sulfide), which is why clay materials are highly compacted: to reduce both physical space and access to water for microorganisms to grow. However, the highly compacted nature of clays and the resulting low activity or dormancy of microorganisms complicate the extraction of biomarkers (i.e., PLFA, DNA etc.) from such barriers for predictive analysis of microbial risks. In order to overcome these challenges, we have combined culture-and 16S rRNA gene amplicon sequencing-based approaches to describe the functional diversity of microorganisms in several commercial clay products, including two different samples of Wyoming type MX-80 bentonite (Batch 1 and Batch 2), the reference clay for a future Canadian DGR, and Avonlea type Canaprill, a clay sample for comparison. Microorganisms from as-received bentonites were enriched in anoxic 10% w/v clay microcosms for three months at ambient temperature with addition of 10% hydrogen along with presumable indigenous organics and sulfate in the clay. High-throughput sequencing of 16S rRNA gene fragments indicated a high abundance of Gram-positive bacteria of the phylum Firmicutes (82%) in MX-80 Batch 1 incubations. Bacterial libraries from microcosms with MX-80 Batch 2 were enriched with Firmicutes (53%) and Chloroflexi (43%). Firmicutes also significantly contributed (<15%) to the bacterial community in Canaprill clay microcosm, which was dominated by Gramnegative Proteobacteria (>70%). Sequence analysis revealed presence of the bacterial families Peptostreptococcaceae, Clostridiaceae, Peptococcaceae, Bacillaceae, Enterobacteriaceae, Veillonellaceae, Tissierellaceae and Planococcaceae in MX-80 Batch 1 incubations; Bacillaceae, along with unidentified bacteria of the phylum Chloroflexi, in MX-80 Batch 2 clay microcosms, and Pseudomonadaceae, Hydrogenophilaceae, Bacillaceae, Desulfobacteraceae, Desulfobulbaceae, Peptococcaceae, Pelobacteraceae, Alcaligenaceae, Rhodospirillaceae in Canaprill microcosms. Exploration of potential metabolic pathways in the bacterial communities from the clay microcosms suggested variable patterns of sulfur cycling in the different clays with the possible prevalence of bacterial sulfatereduction in MX-80 bentonite, and probably successive sulfate-reduction/sulfur-oxidation reactions in Canaprill microcosms. Furthermore, analysis of potential metabolic pathways in the bentonite enrichments suggested that bacteria with acid-producing capabilities (i.e., fermenters and acetogens) together with sulfide-producing prokaryotes might perhaps contribute to corrosion risks in clay systems. However, the low activity or dormancy of microorganisms in highly compacted bentonites as a result of severe environmental constraints (e.g., low water activity and high swelling pressure in the confined bentonite) in situ would be expected to largely inhibit bacterial ...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Prediction of bacterial functional diversity in clay microcosms

Grigoryan

Jalique

Stroes-Gascoyne

et al. 2021

Heliyon

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“…More specifically, the UK design is likely to consist of a carbon steel canister encasing the waste with an MX80 bentonite clay barrier all buried to a depth of 1000 m below the surface (NDA, 2016;NDA, 2010). There are microbial communities associated with MX80 bentonite, as well as groundwaters and host rocks (Chi and Athar, 2008;Hallbeck and Pedersen, 2012;Povedano-Priego et al, 2020;NDA, 2016;Smart et al, 2017;Gilmour et al, 2021). Therefore, in addition to the materials in the repository design and the potential abiotic reactions that could occur, microbes will also be present and microbially influenced reactions must also be considered.…”

Section: Introductionmentioning

confidence: 99%

Survival and activity of an indigenous iron-reducing microbial community from MX80 bentonite in high temperature / low water environments with relevance to a proposed method of nuclear waste disposal

Gilmour

Davie

Gray

2022

Science of The Total Environment

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“…Montmorillonite (MMT) consists of well-defined layers separated by interlayer spaces and has great water absorption potential [1][2][3][4]. Thus, it is often used as clay barriers or adsorption material in environmental geotechnical engineering, for example, the backfill in the nuclear waste disposal and the cushion in the landfill [5][6][7][8][9][10]. It is very challenging to directly measure the fundamental mechanical properties of MMT [11,12].…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulation of Nanoscale Elastic Properties of Hydrated Na-, Cs-, and Ca-Montmorillonite

et al. 2022

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The knowledge of nanoscale mechanical properties of montmorillonite (MMT) with various compensation cations upon hydration is essential for many environmental engineering-related applications. This paper uses a Molecular Dynamics (MD) method to simulate nanoscale elastic properties of hydrated Na-, Cs-, and Ca-MMT with unconstrained system atoms. The variation of basal spacing of MMT shows step characteristics in the initial crystalline swelling stage followed by an approximately linear change in the subsequent osmotic swelling stage as the increasing of interlayer water content. The water content of MMT in the thermodynamic stable-state conditions during hydration is determined by comparing the immersion energy and hydration energy. Under this stable hydration state, the nanoscale elastic properties are further simulated by the constant strain method. Since the non-bonding strength between MMT lamellae is much lower than the boning strength within the mineral structure, the in-plane and out-of-plane strength of MMT has strong anisotropy. Simulated results including the stiffness tensor and linear elastic constants based on the assumption of orthotropic symmetry are all in good agreement with results from the literature. Furthermore, the out-of-plane stiffness tensor components of C33, C44, and C55 all fluctuate with the increase of interlayer water content, which is related to the formation of interlayer H-bonds and atom-free volume ratio. The in-plane stiffness tensor components C11, C22, and C12 decrease nonlinearly with the increase of water content, and these components are mainly controlled by the bonding strength of mineral atoms and the geometry of the hydrated MMT system. Young’s modulus in all three directions exhibits a nonlinear decrease with increasing water content.

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An indigenous iron-reducing microbial community from MX80 bentonite - A study in the framework of nuclear waste disposal

Cited by 18 publications

References 56 publications

Prediction of bacterial functional diversity in clay microcosms

Prediction of bacterial functional diversity in clay microcosms

Survival and activity of an indigenous iron-reducing microbial community from MX80 bentonite in high temperature / low water environments with relevance to a proposed method of nuclear waste disposal

Molecular Dynamics Simulation of Nanoscale Elastic Properties of Hydrated Na-, Cs-, and Ca-Montmorillonite

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