Bacterial Diversity in Bentonites, Engineered Barrier for Deep Geological Disposal of Radioactive Wastes

López-Fernández, Margarita; Cherkouk, Andrea; Vílchez-Vargas, Ramiro; Jáuregui, Ruy; Pieper, Dietmar H.; Boon, Nico; Sánchez-Castro, Iván; Merroun, Mohamed L.

doi:10.1007/s00248-015-0630-7

Cited by 48 publications

(27 citation statements)

References 57 publications

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“…2 The high microbial diversity of these Spanish clays was shown by means of culture dependent and independent techniques. 3,4 In addition, more than 100 microbial strains were isolated from these bentonites including a novel species of the genus Stenotrophomonas (Stenotrophomonas bentonitica BII-R7). 5 The microbial communities of the selected artificial barriers can affect the safety and performance of future DGRs at 3 different levels by: i) transformation of clay minerals; ii) corrosion of metal canisters; and iii) mobilization of radionuclides through different interaction processes.…”

Section: Introductionmentioning

confidence: 99%

Green synthesis and biotransformation of amorphous Se nanospheres to trigonal 1D Se nanostructures: impact on Se mobility within the concept of radioactive waste disposal

Ruiz-Fresneda

Delgado-Martín

Bolívar

et al. 2018

Environ. Sci.: Nano

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Section: Introductionmentioning

confidence: 99%

Green synthesis and biotransformation of amorphous Se nanospheres to trigonal 1D Se nanostructures: impact on Se mobility within the concept of radioactive waste disposal

Ruiz-Fresneda

Delgado-Martín

Bolívar

et al. 2018

Environ. Sci.: Nano

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“…Microbial implications on the performance of the EBS in DGR have been the subject of considerable study ( Stroes-Gascoyne et al., 2006 , 2010 ; Wang and Francis, 2005 ; Humphreys et al., 2010 ; Mulligan et al., 2009 ; Behrends et al., 2012 ; Pedersen, 2010 , 2013 ; Pedersen et al., 2012 ; Lopez-Fernandez et al., 2015 ; Stone et al., 2016 ). As genuine bio-catalysts, bacteria are capable of vigorously modifying their environments through their growth and metabolite production.…”

Section: Introductionmentioning

confidence: 99%

Bacterial diversity and production of sulfide in microcosms containing uncompacted bentonites

Grigoryan

Jalique

Medihala

et al. 2018

Heliyon

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AimsThis study examined the diversity and sulfide-producing activity of microorganisms in microcosms containing commercial clay products (e.g., MX-80, Canaprill and National Standard) similar to materials which are currently considered for use in the design specifications for deep geologic repositories (DGR) for spent nuclear fuel.Methods and resultsIn anoxic microcosms incubated for minimum of 60 days with 10 g l-1 NaCl, sulfide production varied with temperature, electron donor and bentonite type. Maximum specific sulfide production rates of 0.189 d−1, 0.549 d−1 and 0.157 d−1 occurred in lactate-fed MX-80, Canaprill and National Standard microcosms, respectively. In microcosms with 50 g l-1 NaCl, sulfide production was inhibited. Denaturing gradient gel electrophoresis (DGGE) profiling of microcosms revealed the presence of bacterial classes Clostridia, Bacilli, Gammaproteobacteria, Deltaproteobacteria, Actinobacteria, Sphingobacteriia and Erysipelotrichia. Spore-forming and non-spore-forming bacteria were confirmed in microcosms using high-throughput 16S rRNA gene sequencing. Sulfate-reducing bacteria of the genus Desulfosporosinus predominated in MX-80 microcosms; whereas, Desulfotomaculum and Desulfovibrio genera contributed to sulfate-reduction in National Standard and Canaprill microcosms.ConclusionsCommercial clays microcosms harbour a sparse bacterial population dominated by spore-forming microorganisms. Detected sulfate- and sulfur-reducing bacteria presumably contributed to sulfide accumulation in the different microcosm systems.Significance and impact of studyThe use of carbon-supplemented, clay-in-water microcosms offered insights into the bacterial diversity present in as-received clays, along with the types of metabolic and sulfidogenic reactions that might occur in regions of a DGR (e.g., interfaces between the bulk clay and host rock, cracks, fissures, etc.) that fail to attain target parameters necessary to inhibit microbial growth and activity.

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“…In phylogenetic studies of prokaryotes, 16S ribosomal RNA is often selected as the target sequence for species-specific targeted amplification because of its conservative evolution and stable high expression [49, 50]. Interestingly, the 16S gene is also one of the most commonly used reference genes in qPCR experiments involving cyanobacteria [24, 29, 51–54].…”

Section: Discussionmentioning

confidence: 99%

Stable Reference Gene Selection for RT-qPCR Analysis inSynechococcus elongatusPCC 7942 under Abiotic Stresses

Luo

Chang

et al. 2019

BioMed Research International

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Synechococcus elongatus PCC 7942 (S. elongatus PCC 7942) is a model cyanobacteria species for circadian clock mechanism studies. It has also been widely used as a bioreactor to produce biofuels and other metabolic products. Quantitative real-time PCR (qPCR) technology is the most commonly used method for studying the expression of specific genes, in which the relative expression level of target genes is calibrated by stably expressed internal reference genes. In this work, we examined the expression of nine candidate reference genes in time-course samples of S. elongatus PCC 7942 under no treatment (control), NaCl-stress conditions, H2O2-stress conditions, and high light-stress conditions. Based on the qPCR amplification parameters, the stability ranking of these candidate reference genes was established by three statistical software programs, geNorm, NormFinder, and BestKeeper. Considering all the stress conditions or high light stress alone, the results showed that the combination of prs and secA was the best choice for the double reference gene calibration method by qPCR. The combination of secA and ppc, rimM and rnpA, rnpA, and ilvD was most stable under no treatment, NaCl-stress conditions, and H2O2-stress conditions, respectively. rimM was stable under only special conditions and should be carefully chosen. 16S and rnpB were not suitable as internal reference genes for S. elongatus PCC 7942 qPCR experiments under all experimental conditions. To validate the above results, a cyanobacterial core clock gene, kaiC, was used to evaluate the actual performance of the optimized reference genes by qPCR, as well as the worst reference genes under different stress conditions. The results indicated that the best reference gene yielded more accurate calibration results for qPCR experiments carried out in S. elongatus PCC 7942 time-course samples.

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Bacterial Diversity in Bentonites, Engineered Barrier for Deep Geological Disposal of Radioactive Wastes

Cited by 48 publications

References 57 publications

Green synthesis and biotransformation of amorphous Se nanospheres to trigonal 1D Se nanostructures: impact on Se mobility within the concept of radioactive waste disposal

Green synthesis and biotransformation of amorphous Se nanospheres to trigonal 1D Se nanostructures: impact on Se mobility within the concept of radioactive waste disposal

Bacterial diversity and production of sulfide in microcosms containing uncompacted bentonites

Stable Reference Gene Selection for RT-qPCR Analysis inSynechococcus elongatusPCC 7942 under Abiotic Stresses

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