Deep Biosphere Quantification in Chesapeake Bay Impact Structure Sediments
Final Report Abstract
The DFG funded project exclusively investigated the terrestrial deep biosphere of the post-impact sediments of the Chesapeake Bay Impact Structure (CBIS) while all other microbiologists (from abroad) of the ICDP CBIS drilling project focused on the deeper impact sediment and breccia layers. A continuous coring of the upper 140 m sediment layer of upper Miocene, Pliocene, and Pleistocene post-impact sediments was done in Corehole C at the Eyreville drillsite in spring 2006 by the US Geological Survey. 50 sediment core samples from various depths were taken by the BGR geomicrobiology group on the drillsite. The main objective was the quantification of living prokaryotes and of abundant prokaryotic groups using the nucleic-acid based quantitative molecular techniques real-time PCR (Q-PCR) and catalyzed reporter deposition - fluorescence in situ hybridisation (CARD - FISH) in combination with total cell counting. The prokaryotic diversity was studied by cloning and sequencing of 16S rRNA genes. Microbial activities were measured via CO2 release in incubation experiments. Total cell counts decreased from 109 to 106 cells per g dry weight (dw) within the uppermost 20 m depth and fluctuated around this value below. A significant proportion of the total cell counts could be detected with CARD-FISH within the uppermost 7 m depth. The CARD FISH numbers for Bacteria were about an order of magnitude higher than those for the Archaea. The dominance of Bacteria over Archaea was confirmed by real-time PCR (Q-PCR) analysis done for the uppermost 10 m depth and for 80-140 m depth. In addition to the prokaryotic domains, also Eukarya, and specific prokaryotic groups were quantified via Q-PCR by 18S rRNA or 16S rRNA or functional gene quantification. The bacterial candidate division JS-1 and the classes Anaerolineae and Caldilineae of the phylum Chloroflexi, and the functional gene cbbL coding for RubisCO were found up to the maximum sampling depth in high copy numbers. Eukarya and the Fe(III)- and Mn(IV)-reducing bacterial group Geobacteriaceae were almost only found in the uppermost meter (arable soil), where reactive iron was detected in higher amounts. The functional genes aprA and dsrA of sulfate reducing bacteria were found within distinct layers up to ca. 100 m depth in low copy numbers. The gene mcrA was not detectable. The project provided the first quantitative molecular data for the deep biosphere of terrestrial sediments.
Publications
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2007. Influence of impacts on the deep subsurface biosphere – Preliminary results from the ICDP-USGS Chesapeake Bay Impact Structure Drilling Project. GSA Annual Meeting, Denver, USA
Cockell, C., M. Voytek, A. Gronstal, J. Kirshtein, K. Finster, A. Schippers, A.-L. Reysenbach, G. Gohn, W. Sanford, and W. Horton
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2008. Nucleic acid based quantitative microbial community analysis in different marine and terrestrial sediments. International Symposium for Subsurface Microbiology (ISSM 2008), Shizouka, Japan
Schippers, A., A. Blazejak, and G. Köweker
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2009. Deep biosphere quantification in different marine and terrestrial sediments. 109th General Meeting of the American Society for Microbiology (ASM), Philadelphia, USA
Schippers, A.
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2010. Quantification of microbial communities in three forearc sediment basins off Sumatra. Geomicrobiol. J. 27: 170-182
Schippers, A., G. Köweker, C. Höft, and B. Teichert
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2011. Real-time PCR quantification of Bacteria and Archaea in subsurface marine sediments. Dark Energy Biosphere Institute Research Coordination Network (DEBI-RCN), 2011 Meeting, Deep Biosphere Sediment Microbiology, Chapel Hill, North Carolina, USA
Breuker, A., and A. Schippers
