Woods Hole Oceanographic Institution

Marco Coolen

»Bioavailability of soil organic matter and microbial community dynamics upon permafrost thaw
»7000 years of virus-host molecular dynamics in the Black Sea
»Preservation potential of ancient DNA in Pleistocene marine sediments: Implications for paleoenvironmental reconstructions
»Source-specific variability in post-depositional DNA preservation with potential implications for DNA-based paleecological records
»Exploring preserved ancient dinoflagellalte and haptophyte DNA signatures to infer ecological and environmental conditions during sapropel S1 formation in the eastern Mediterranean
»Ancient DNA in lake sediment records
»Vertical distribution of metabolically active eukaryotes in the water column and sediments of the Black Sea
»DNA and lipid molecular stratigraphic records of haptophyte succession in the Black Sea during the Holocene
»Diversity of Archaea and potential for crenarchaeotal nitrification of group 1.1a in the rivers Rhine and TĂȘt
»Holocene sources of fossil BHPs
»An unusual 17[α],21[β](H)-bacteriohopanetetrol in Holocene sediments from Ace Lake (Antarctica)
»Holocene sources of organic matter in Antarctic fjord
»Variations in spatial and temporal distribution of Archaea in the North Sea
»Archaeal nitrifiers in the Black Sea
»Pleistocene Mediterranean sapropel DNA
»Rapid sulfurisation of highly branched isoprenoid (HBI) alkenes in sulfidic Holocene sediments
»Aerobic and anaerobic methanotrophs in the Black Sea water column
»Fossil DNA in Cretaceous Black Shales: Myth or Reality?
»Sulfur and methane cycling during the Holocene in Ace Lake (Antarctica)
»Ancient algal DNA in the Black Sea
»Archaeal nitrification in the ocean
»Characterization of microbial communities found in the human vagina by analysis of terminal restriction fragment length polymorphisms of 16S rRNA genes
»Biomarker and 16S rDNA evidence for anaerobic oxidation of methane and related carbonate precipitation in deep-sea mud volcanoes of the Sorokin Trough, Black Sea
»Temperature-dependent variation in the distribution of tetraether membrane lipids of marine Crenarchaeota: Implications for TEX86 paleothermometry
»Paleoecology of algae in Ace Lake
»Evolution of the methane cycle in Ace Lake (Antarctica) during the Holocene: Response of methanogens and methanotrophs to environmental change
»Ongoing modification of Mediterranean Pleistocene sapropels mediated by prokaryotes.
»Microbial communities in the chemocline of a hypersaline deep-sea basin (Urania basin, Mediterranean Sea)
»Functional exoenzymes as indicators of metabolically active bacteria in 124,000-year-old sapropel layers of the Eastern Mediterranean Sea
»Specific detection of different phylogenetic groups of chemocline bacteria based on PCR and denaturing gradient gel electrophoresis of 16S rRNA gene fragments
»Analysis of subfossil molecular remains of purple sulfur bacteria in a lake sediment
»Effects of nitrate availability and the presence of Glyceria maxima the composition and activity of the dissimilatory nitrate-reducing bacterial community
»Microbial activities and populations in upper sediment and sapropel layers

Sass, A. M., H. Sass, M. J. L. Coolen, H. Cypionka and J. Overmann, Microbial communities in the chemocline of a hypersaline deep-sea basin (Urania basin, Mediterranean Sea), Appl. Environ. Microbiol., 67(12), 5392-5402, 2001

The Urania basin is a hypersaline sulfidic brine lake at the bottom of the eastern Mediterranean Sea. Since this basin is located at a depth of approximately 3,500 m below the sea surface, it receives only a small amount of phytoplankton organic carbon. In the present study, the bacterial assemblages at the interface between the hypersaline brine and the overlaying seawater were investigated. The sulfide concentration increased from 0 to 10 mM within a vertical interval of 5 m across the interface. Within this chemocline, the total bacterial cell counts and the exoenzyme activities were elevated. Employing 11 cultivation methods, we isolated a total of 70 bacterial strains. The 16S ribosomal DNA sequences of 32 of the strains were identical to environmental sequences detected in the chemocline by culture-independent molecular methods. These strains were identified as flavobacteria, Alteromonas macleodii, and Halomonas aquamarina. All 70 strains could grow chemoorganoheterotrophically under oxic conditions. Sixty-six strains grew on peptone, casein hydrolysate, and yeast extract, whereas only 15 strains did not utilize polymeric carbohydrates. Twenty-one of the isolates could grow both chemoorganotrophically and chemolithotrophically. While the most probable numbers in most cases ranged between 0.006 and 4.3% of the total cell counts, an unusually high value of 54% was determined above the chemocline with media containing amino acids as the carbon and energy source. Our results indicate that culturable bacteria thriving at the oxic-anoxic interface of the Urania basin differ considerably from the chemolithoautotrophic bacteria typical of other chemocline habitats. Full text of this article can be viewed here.

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