GENOMICS OF GLACIECOLA SP., A PREDOMINANT BACTERIUM IN ANTARCTIC WINTER SEA-ICE

• Main Authors: Helmke, Elisabeth, Beszteri, Bank, Frickenhaus, Stephan, Valentin, Klaus-Ulrich, Wichels, Antje, Wohlrab, Sylke, Thoms, Silke, Kube, Michael, Reinhardts, Richard
• Format: Conference Object
• Language: unknown
• Published: 2013
• Subjects: Arctic; Antarctic; Southern Ocean; Weddell Sea; Weddell; Antarc*; Sea ice
• Online Access: https://epic.awi.de/id/eprint/33600/; https://hdl.handle.net/10013/epic.42050

About 20 Million km2 of sea ice covers the Southern Ocean in winter which retreats to about 6 Million km2 in summer. In spite of the harsh temperature and salinity conditions a so-called sea-ice microbial community thrives within the liquid brine system. Sea-ice organisms are very closely adapted to their habitat. Although in recent years several genomic projects started with bacteria from polar sea ice the genomic basis of their adaptation strategies is still unknown. Hence, further complete genome sequences of other members of the sea-ice communities are required to improve our understanding. For a complete genome sequencing the bacterium Glaciecola sp. was chosen which constituted more than 25% of our isolates from winter pack ice of the Weddell Sea and was also regularly isolated from Arctic summer sea ice. The nearest relatives of this group on the 16S rRNA gene basis are the type strains G. psychrophila and G. mesophila. The complete genome sequence of Glaciecola sp. 9081 comprises one circular chromosome with 4.99 Mega base pairs. A total of 5800 open reading frames was predicted. Based on annotation of proteins by sequence similarity we found genes for the production and transport of osmolytes that may balance the osmotic pressure of the cell when sea ice freezes. Further, genes involved in the production of extracellular polysaccharides were detected that may play a role in cold adaptation by lowering the freezing point in the vicinity of the cell. In ongoing studies we are trying to unravel further molecular concepts of cold adaptation.