Metagenomics studies of deep terrestrial biosphere of Fennoscandian Shield

Molecular microbial studies of several deep boreholes ranging from 300 to 2500 m reveal considerable diversity of bacteria, archaea, fungi and viruses in the Fennoscandian Shield. The cell counts decrease with depth even if the temperatures at 2.5 km are only around 40 oC. The major probable selective as-pects are salinity, increasing pressure and oligotrophic mineralogical conditions. The major carbon source is methane evolving from the fractures in the bedrock, and also small quantities of carbon dioxide and hydrogen are present. Whole metagenome sequencing by Illumina HiSeq and Roche 454 was done in order to gain deeper insight into the metabolism of the deep earth crust microbiomes in the Outokumpu deep borehole (2.5km). Assemply of the reads resulted in 2.5 million contigs from which ca. 5 million proteins were predicted. Significant sequence homology was inferred for 2.2 million proteins, which were classified on the basis of KEGG orthology. The study and modelling of the pathways of these proteins is ongoing. In addition, the deep microbiome proteins are studied in vitro by using heterologous expression of metagenome derived enzyme genes.