The Baltic Sea has low surface salinity and a steep halocline with anoxic bottom areas. The total reserves of nitrogen in the Baltic have been rising, and denitrification is a key process in balancing the nitrogen budget. We propose to study whether anammox bacteria contribute to denitrification using environmental genomics. We will also use such techniques to study the overall diversity and extent of stratification of microbial species in the water column and sediments across a steep oxygen gradient. We will study microbial diversity (archaeal and bacterial) using 16S ribosomal RNA gene and metagenomic sequencing, and in addition, will develop ribonucleotide reductases as novel biomarkers for oxic-anoxic habitability.
The study has a clear environmental relevance since virtually nothing is known about the anammox reaction in the Baltic Sea. There is also a potentially interesting evolutionary perspective, as the anammox bacteria form a distinct monophyletic group within the Planctomycetes, an enigmatic group of bacteria with internal cell structure superficially similar to the eukaryote cell plus nucleus.