title: A minimalistic microbial food web in an excavated deep subsurface clay rock.
abstract: Clay rocks are being considered for radioactive waste disposal, but relatively little is known about the impact of microbes on the long-term safety of geological repositories. Thus, a more complete understanding of microbial community structure and function in these environments would provide further detail for the evaluation of the safety of geological disposal of radioactive waste in clay rocks. It would also provide a unique glimpse into a poorly studied deep subsurface microbial ecosystem. Previous studies concluded that microorganisms were present in pristine Opalinus Clay, but inactive. In this work, we describe the microbial community and assess the metabolic activities taking place within borehole water. Metagenomic sequencing and genome-binning of a porewater sample containing suspended clay particles revealed a remarkably simple heterotrophic microbial community, fueled by sedimentary organic carbon, mainly composed of two organisms: a Pseudomonas sp. fermenting bacterium growing on organic macromolecules and releasing organic acids and H2, and a sulfate-reducing Peptococcaceae able to oxidize organic molecules to CO(2). In Opalinus Clay, this microbial system likely thrives where pore space allows it. In a repository, this may occur where the clay rock has been locally damaged by excavation or in engineered backfills.
authors.affiliation: Environmental Microbiology Laboratory, EPFL, Building CH, CH A1 375, Station 6, Lausanne, 1015, Switzerland.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Bagnoud
authors.affiliation: Science for Life Laboratory, Bioinformatics Infrastructure for Life Sciences, Tomtebodavägen 23, Stockholm, 171 65, Sweden.
authors.forename: Ino
authors.initials: I
authors.lastname: de Bruijn
authors.affiliation: Science for Life Laboratory, KTH Royal Institute of Technology, Tomtebodavägen 23, Stockholm, 171 65, Sweden.
authors.forename: Anders F
authors.initials: AF
authors.lastname: Andersson
authors.affiliation: NAGRA, National Cooperative for the Disposal of Radioactive Waste, Hardstrasse 73, Wettingen, 5430, Switzerland.
authors.forename: Nikitas
authors.initials: N
authors.lastname: Diomidis
authors.affiliation: NAGRA, National Cooperative for the Disposal of Radioactive Waste, Hardstrasse 73, Wettingen, 5430, Switzerland.
authors.forename: Olivier X
authors.initials: OX
authors.lastname: Leupin
authors.affiliation: NAGRA, National Cooperative for the Disposal of Radioactive Waste, Hardstrasse 73, Wettingen, 5430, Switzerland.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schwyn
authors.affiliation: Environmental Microbiology Laboratory, EPFL, Building CH, CH A1 375, Station 6, Lausanne, 1015, Switzerland rizlan.bernier-latmani@epfl.ch.
authors.forename: Rizlan
authors.initials: R
authors.lastname: Bernier-Latmani
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D000077215:Clay; D017753:Ecosystem; D020387:Food Chain; D052836:Heterotrophic Processes; D053858:Metabolic Networks and Pathways / Q000235:genetics; D056186:Metagenomics; D064307:Microbiota / Q000235:genetics*; D010459:Peptococcaceae / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011549:Pseudomonas / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D011850:Radioactive Waste; D012037:Refuse Disposal; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D013431:Sulfates / Q000378:metabolism; D013557:Switzerland
chemical_list: D000538:Aluminum Silicates; D012336:RNA, Ribosomal, 16S; D011850:Radioactive Waste; D012987:Soil; D013431:Sulfates; D000077215:Clay
keywords: Opalinus Clay; deep subsurface; metagenomics; microbial activity; sulfate reduction