The multi- and interdisciplinary aspects of MicroBent include the use of molecular biology to describe microbial populations and metabolisms in a repository system through metaomics, and directly applied to the storage of highly radioactive waste. MicroBent will bridge the knowledge gaps (Table 1) in current areas and enhance tools to determine microbial activity. Applied knowledge of microbial population and their active metabolic pathways will benefit other scientific areas dependant on microbiomes (i.e. bioremediation industry, biotechnology and astrobiology).
The main objectives are:
1. Geochemical and mineralogical characterization of the groundwaters and bentonites incubated under in situ conditions.
2. Identify the microbial community of the incubated compacted bentonites by culture-dependent methods
3. Characterize the isolate metabolisms and their influence in the DGR.
Main achievements:
- Geochemical analysis confirmed the groundwaters chemical stability and neutral pH. However, they had different chemical compositions and could be characterized with regard to origin and age. The bentonite composition was dominated by SiO2, plus calcium and magnesium oxides, with light variations after the incubation.
- The mineralogy of the bentonite samples was dominated by smectites (calcium montmorillonite) and plagioclases, combined with minor quantities of quartz, cristobalite and mica. Newly formed Fe minerals were identified after the in situ incubation.
- A total of 12 microorganisms were isolated from the enrichments and identified by 16S rRNA gene sequencing, affiliated to Firmicutes and Proteobacteria phyla, with metabolisms involved in sulfate reduction plus iron oxidation coupled to nitrate reduction.
