Glaring, Mikkel Andreas4; Vester, Jan Kjølhede4; Lylloff, Jeanette Eva5; Abu Al-Soud, Waleed6; Sørensen, Søren Johannes6; Stougaard, Peter5
1 Microbial Ecology and Biotechnology, Department of Plant and Environmental Sciences, Faculty of Science, Københavns Universitet2 Microbiology, Department of Biology, Faculty of Science, Københavns Universitet3 Department of Agriculture & Ecology, Genetics & Microbiology, Department of Agriculture & Ecology, Faculty of Life Sciences, Københavns Universitet4 Department of Agriculture & Ecology, Genetics & Microbiology, Department of Agriculture & Ecology, Faculty of Life Sciences, Københavns Universitet5 Microbial Ecology and Biotechnology, Department of Plant and Environmental Sciences, Faculty of Science, Københavns Universitet6 Microbiology, Department of Biology, Faculty of Science, Københavns Universitet
The submarine ikaite columns located in the Ikka Fjord in Southern Greenland represent a unique, permanently cold (less than 6°C) and alkaline (above pH 10) environment and are home to a microbial community adapted to these extreme conditions. The bacterial and archaeal community inhabiting the ikaite columns and surrounding fjord was characterised by high-throughput pyrosequencing of 16S rRNA genes. Analysis of the ikaite community structure revealed the presence of a diverse bacterial community, both in the column interior and at the surface, and very few archaea. A clear difference in overall taxonomic composition was observed between column interior and surface. Whereas the surface, and in particular newly formed ikaite material, was primarily dominated by Cyanobacteria and phototrophic Proteobacteria, the column interior was dominated by Proteobacteria and putative anaerobic representatives of the Firmicutes and Bacteroidetes. The results suggest a stratification of the ikaite columns similar to that of classical soda lakes, with a light-exposed surface inhabited by primary producers and an anoxic subsurface. This was further supported by identification of major taxonomic groups with close relatives in soda lake environments, including members of the genera Rhodobaca, Dethiobacter, Thioalkalivibrio and Tindallia, as well as very abundant groups related to uncharacterised environmental sequences originally isolated from Mono Lake in California.