title: In situ bacterial colonization of compacted bentonite under deep geological high-level radioactive waste repository conditions.
abstract: Subsurface microorganisms are expected to invade, colonize, and influence the safety performance of deep geological spent nuclear fuel (SNF) repositories. An understanding of the interactions of subsurface dwelling microbial communities with the storage is thus essential. For this to be achieved, experiments must be conducted under in situ conditions. We investigated the presence of groundwater microorganisms in repository bentonite saturated with groundwater recovered from tests conducted at the Aspö underground Hard Rock Laboratory in Sweden. A 16S ribosomal RNA and dissimilatory bisulfite reductase gene distribution between the bentonite and groundwater samples suggested that the sulfate-reducing bacteria widespread in the aquifers were not common in the clay. Aerophilic bacteria could be cultured from samples run at <or=55 degrees C but not at >or=67 degrees C. Generally, the largely gram-negative groundwater microorganisms were poorly represented in the bentonite while the gram-positive bacteria commonly found in the clay predominated. Thus, bentonite compacted to a density of approximately 2 g cm(-3) together with elevated temperatures might discourage the mass introduction of the predominantly mesophilic granitic aquifer bacteria into future SNF repositories in the long run.
authors: Department of Cell and Molecular Biology, Göteborg University Sweden, PO Box 462, Gothenburg, Sweden. E.chi-fru@Uea.ac.uk
authors: E
authors: E
authors: Chi Fru
authors: R
authors: R
authors: Athar
mesh_terms: D000332:Aerobiosis; D000538:Aluminum Silicates / Q000032:analysis; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001546:Bentonite / Q000032:analysis*; D000077215:Clay; D004275:DNA, Ribosomal / Q000235:genetics; D019015:Geologic Sediments / Q000382:microbiology*; D052836:Heterotrophic Processes; D050885:Hydrogensulfite Reductase / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D011850:Radioactive Waste / Q000032:analysis*; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D013548:Sweden; D014871:Water Microbiology
chemical_list: D000538:Aluminum Silicates; D001426:Bacterial Proteins; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D011850:Radioactive Waste; D001546:Bentonite; D050885:Hydrogensulfite Reductase; D000077215:Clay