Metagenomic studies of the diversity and function of chemosynthetic microbial communities at oceanic spreading zones
Final Report Abstract
Metagenome analysis was used in order to study the genetic capabilities of free-living microorganisms at the Logatchev hydrothermal field (LHF) that are numerically and functionally important. In the initial phase, it turned out that cell counts in hydrothermal fluid would not be sufficient for classical metagenomomic fosmid library construction, whereas the cell densities in hydrothermal sediments were expectedly sufficient and the DNA was readily clonable. Subsequent studies focused on characteristic white-covered sediment patches within LHF. In an interdisciplinary approach, for the first time conductively heated, diffusion controlled, sulfur rich sediments at an ultramafic-hosted hydrothermal field were investigated. We found that in these sediments both microorganisms related to epsilonproteobacterial hydrogen sulfide-oxidizers and deltaproteobacterial sulfate-reducers are present in high numbers in the surface sediments, and that it is rather the oxidation and reduction of sulfurcompounds which shapes the microbial community in mat-covered sediments at LHF than the oxidation of methane or hydrogen, which are enriched in endmember fluids at LHF. In this habitat description we performed microbial turnover rate measurements, clone library construction and comparative sequence analysis as well as fluorescence in situ hybridization. Subsequently, metagenomics was applied in order to assess the genetic potential of the microbial community in the surface layer of one of the white-covered sediments. A fosmid library was constructed, and screened for the phylogenetic marker 16S rRNA, and genes coding for a key protein of the sulfur metabolism (aprA) and hydrogen oxidation (hupL). Selected fosmids were completely sequenced. Fosmid insert end sequences were used to select a set of 42 fosmids likely originating from Epsilonproteobacteria for sequencing in order to get a more unbiased access to the genetic information of this class. Additionally, about 1 Mio. sequence reads of on average 350 bp sequence length were generated from site F metagenomic DNA by 454 pyrosequecing technology. The applicability of 454 pyrosequencing for microbial community structure analysis was evaluated in comparison to other methods, and taxonomic binning of the deduced protein dataset allowed for the detection of characteristic metabolic capabilities of taxonomic groups. Datasets created are in line with the proposed project, except for the application of 454 pyrosequencing, which became the method of choice for metagenome analysis during the project. Moreover, planned mRNA expression analysis failed. All sequence data will be made available via international databases, including Pangaea.
Publications
- Diversity and function of chemosynthetic microbial communities in sediments of the Logatchev hydrothermal vent area. 11th International Symposium on Microbial Ecology (ISME), Vienna, Austria. August 2006
R. Schauer, A. Meyerdierks, R. Amann
- Characterization of chemosynthetic microbial communities in warm, white covered sediments at the Logatchev hydrothermal vent field. InterRidge Theoretical Institute “Biogeochemical Interaction at Deep-Sea Vents”, Woods Hole, USA. September 2007
R. Schauer, H. Røy, H.-H. Gennerich, R. Amann A. Meyerdierks
- Chemosynthetic microbial communities in hydrothermal vent sediments: diversity and function. VAAM Annual Conference 2007, Osnabrück, Germany. April 2007
R. Schauer, A. Meyerdierks, R. Amann
- Diversity and abundance of the primary producers in deep-sea hydrothermal vent sediments 107th General Meeting of the American Society for Microbiology (ASM), Toronto, Canada. May 2007
R. Schauer, A. Meyerdierks, R. Amann
- Molecular and geochemical investigation of sediments covered with white mats at the Logatchev hydrothermal vent field. Goldschmidt Conference, Cologne, Germany. August 2007
R. Schauer, H. Røy, H.-H. Gennerich, A. Meyerdierks and R. Amann
- Free-living microbial communities in different sediments of the Logatchev hydrothermal vent field: Diversity, Function and Ecological Significance. SPP1144 workshop, Etelsen, Germany. Juli 2008
R. Schauer, H. Røy, H.-H. Gennerich, N. Augustin, M. Peters, A. Meyerdierks, R. Amann
- Microbial ecology of sediments in the Logatchev hydrothermal vent field: What is Microbial chemosynthesis based on? 12th International Symposium on Microbial Ecology (ISME), Cairns, Australia. August 2008
R. Schauer, H. Røy, H.-H. Gennerich, A. Meyerdierks, R. Amann
- Sulfatereducing bacteria: key players in white covered sediments of the Logatchev hydrothermal vent field. Scientific Committee on Oceanic Research (SCOR), Woods Hole, USA. October 2008
R. Schauer, H. Røy, H.-H. Gennerich, M. Peters, R. Amann, A. Meyerdierks
- Diversity and function of microbial communities in sediments from different deep-sea habitats. Doctoral thesis, University of Bremen (2010)
Regina Schauer
