The deep terrestrial subsurface environment is distinct from the shallow subsurface due to significantly longer groundwater residence times and represents regional rather than local precipitation-responsive hydrology. The presence of a large, deep subsurface biomass (2-19% of the earth’s biomass) has fundamental scientific implications as well as practical impact on large-scale engineering projects (eg nuclear waste storage, bioremediation of surface water). Nutrient and energy transformation pathways in the Earth’s subsurface are poorly understood and it is not well known how such oligotrophic environments can support life in the terrestrial deep biosphere. The deep subsurface is also important as a potential reservoir for microbes that evolved with evolutionary pressures distinct from those at the surface and may also be relevant for constraining putative life on other planets.
At the moment, our group is carrying out a thorough taxonomic and functional profiling of the deep biosphere through the analysis of metagenomic and metatranscriptomic samples from different depths of several sites located in Sweden and Finland. Sequencing of single amplified genomes (SAGs) from the same sites are also currently being carried out in collaboration with the Joint Genome Institute (JGI). It is clearly evident that this project requires large-scale analysis of a massive amount of data. Outcomes of the analyses will address fundamental questions related to the nutrient cycling and earth's energy.