Deciphering indigenous bacteria in compacted bentonite through a novel and efficient DNA extraction method: Insights into biogeochemical processes within the Deep Geological Disposal of nuclear waste concept
Metadatos
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Elsevier
Materia
DGR Compaction Microbial diversity DNA extraction Protocol Sequencing
Date
2021-02Referencia bibliográfica
Povedano-Priego, C., Jroundi, F., Lopez-Fernandez, M., Shrestha, R., Spanek, R., Martín-Sánchez, I., ... & Merroun, M. L. (2021). Deciphering indigenous bacteria in compacted bentonite through a novel and efficient DNA extraction method: Insights into biogeochemical processes within the Deep Geological Disposal of nuclear waste concept. Journal of Hazardous Materials, 408, 124600. [https://doi.org/10.1016/j.jhazmat.2020.124600]
Résumé
Compacted bentonites are one of the best sealing and backfilling clays considered for use in Deep Geological
Repositories of radioactive wastes. However, an in-depth understanding of their behavior after placement in the
repository is required, including if the activity of indigenous microorganisms affects safety conditions. Here we
provide an optimized phenol:chloroform based protocol that facilitates higher DNA-yields when other methods
failed. To demonstrate the efficiency of this method, DNA was extracted from acetate-treated bentonites compacted
at 1.5 and 1.7 g/cm3 densities after 24 months anoxic incubation. Among the 16S rRNA gene sequences
identified, those most similar to taxa mediating biogeochemical sulfur cycling included sulfur oxidizing (e.g.,
Thiobacillus, and Sulfurimonas) and sulfate reducing (e.g., Desulfuromonas and Desulfosporosinus) bacteria. In
addition, iron-cycling populations included iron oxidizing (e.g., Thiobacillus and Rhodobacter) plus reducing taxa
(e.g., Geobacillus). Genera described for their capacity to utilize acetate as a carbon source were also detected
such as Delftia and Stenotrophomonas. Lastly, microscopic analyses revealed pores and cracks that could host
nanobacteria or spores. This study highlights the potential role of microbial driven biogeochemical processes in
compacted bentonites and the effect of high compaction on microbial diversity in Deep Geological Repositories.