Deep life in Fennoscandian Shield: metagenomics studies of deep microbiome an insight into species diversity and their functions

The continental earth crust contains regions of very different age and composition including crystalline rocks, metamorphic systems, sedimentary basins and organic deposits, and magmatic intrusions. Throughout the crust, fluids are the principal agents in transporting and focusing Earth's energy and mineral resources. In Finland the earth crust is around 50km deep and the bedrock is very stable crystal-line bedrock which is also supposed to be safe for long term storage of nuclear wastes. Deep terrestrial subsurface microbial populations are still highly unexplored, and their origin and interactions with surface populations are not known. In Finland we have access to several deep sampling sites and have developed microbiological sampling techniques. The main goal of our studies have been to characterize the biodiversity of Fennoscandian Shield microbiome and sources of carbon and energy in the bedrock of Finland. Based on considerable efforts to analyse both active and latent microbial communities and eval-uate how addition of electron acceptors and donors affect the microbial communities we have found that in most cases deep subsurface microbial communities are 'sleeping' e.g at their maintainance energy level but may be activated due to environmental changes such as evolution of methane and hydrogen from the deep earth crust. Our studies based on metagenomics have revealed several ongoing processes such as deep nitrogen fixation, carbon cycling and other geobiological processes occurring in deep terrestrial habitats.