Methanogenic community composition and anaerobic carbon turnover in submarine permafrost sediments of the Siberian Laptev Sea

Summary The Siberian Laptev Sea shelf contains submarine permafrost, which was formed by flooding of terrestrial permafrost with ocean water during the Holocene sea level rise. This flooding resulted in a warming of the permafrost to temperatures close below 0°C. The impact of these environmental ch...

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Bibliographic Details
Published in:Environmental Microbiology
Main Authors: Koch, Katharina, Knoblauch, Christian, Wagner, Dirk
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 2009
Subjects:
Online Access:http://dx.doi.org/10.1111/j.1462-2920.2008.01836.x
https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1462-2920.2008.01836.x
http://onlinelibrary.wiley.com/wol1/doi/10.1111/j.1462-2920.2008.01836.x/fullpdf
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Summary:Summary The Siberian Laptev Sea shelf contains submarine permafrost, which was formed by flooding of terrestrial permafrost with ocean water during the Holocene sea level rise. This flooding resulted in a warming of the permafrost to temperatures close below 0°C. The impact of these environmental changes on methanogenic communities and carbon dynamics in the permafrost was studied in a submarine permafrost core of the Siberian Laptev Sea shelf. Total organic carbon (TOC) content varied between 0.03% and 8.7% with highest values between 53 and 62 m depth below sea floor. In the same depth, maximum methane concentrations (284 nmol CH 4 g −1 ) and lowest carbon isotope values of methane (−72.2‰ VPDB) were measured, latter indicating microbial formation of methane under in situ conditions. The archaeal community structure was assessed by a nested polymerase chain reaction (PCR) amplification for DGGE, followed by sequencing of reamplified bands. Submarine permafrost samples showed a different archaeal community than the nearby terrestrial permafrost. Samples with high methane concentrations were dominated by sequences affiliated rather to the methylotrophic genera Methanosarcina and Methanococcoides as well as to uncultured archaea. The presented results give the first insights into the archaeal community in submarine permafrost and the first evidence for their activity at in situ conditions.