Active microbial community structure of deep subsurface sediments within Baltic Sea Basin

Monday, 15 December 2014
Brandi K Reese1, Laura Zinke1, Gustavo Carvalho1, Karen G Lloyd2, Ian Marshall3, Alexander Shumaker2 and Jan Amend1, (1)University of Southern California, Los Angeles, CA, United States, (2)University of Tennessee, Knoxville, TN, United States, (3)Aarhus University, Aarhus, Denmark
The Baltic Sea Basin (BSB) is a unique depositional setting that has experienced periods of glaciation and deglaciation as a result of climatic fluctuations over past tens of thousands of years. This has resulted in laminated sediments formed during periods with strong permanent salinity stratification. The high sedimentation rates make this an ideal setting to understand the microbial structure of a deep biosphere community in a relatively high carbon, and thus high-energy environment, compared to other deep subsurface sites. Samples were collected through scientific drilling during the International Ocean Discovery Program (IODP) Expedition 347 on board the Greatship Manisha, September-November 2013. We examined the active microbial community structure using the 16S rRNA gene transcript and active functional genes through metatranscriptome sequencing. Major biogeochemical shifts have been observed in response to the depositional history between the limnic, brackish, and marine phases. The active microbial community structure in the BSB is diverse and reflective of the unique changes in the geochemical profile. These data further refine our understanding of the existence life in the deep subsurface and the survival mechanisms required for this extreme environment.