Methanogenic activity and diversity in the centre of the Amsterdam Mud Volcano, Eastern Mediterranean Sea

Type Article
Date 2012-07
Language English
Author(s) Lazar Cassandre1, Parkes R. John2, Cragg Barry A.2, L'Haridon Stephane3, Toffin LaurentORCID4
Affiliation(s) 1 : Univ N Carolina, Dept Marine Sci, Chapel Hill, NC 27515 USA.
2 : Cardiff Univ, Sch Earth & Ocean Sci, Cardiff, S Glam, Wales.
3 : Univ Bretagne Occidentale, Lab Microbiol Environm Extremes, UMR 6197, Plouzane, France.
4 : IFREMER,Ctr Brest,Dept Etud Environm Profonds, Plouzane, France.
Source Fems Microbiology Ecology (0168-6496) (Wiley-blackwell), 2012-07 , Vol. 81 , N. 1 , P. 243-254
DOI 10.1111/j.1574-6941.2012.01375.x
WOS© Times Cited 20
Keyword(s) methanogenesis, mcrA, Archaea
Abstract Marine mud volcanoes are geological structures emitting large amounts of methane from their active centres. The Amsterdam mud volcano (AMV), located in the Anaximander Mountains south of Turkey, is characterized by intense active methane seepage produced in part by methanogens. To date, information about the diversity or the metabolic pathways used by the methanogens in active centres of marine mud volcanoes is limited. 14C-radiotracer measurements showed that methylamines/methanol, H2/CO2 and acetate were used for methanogenesis in the AMV. Methylotrophic methanogenesis was measured all along the sediment core, Methanosarcinales affiliated sequences were detected using archaeal 16S PCR-DGGE and mcrA gene libraries, and enrichments of methanogens showed the presence of Methanococcoides in the shallow sediment layers. Overall acetoclastic methanogenesis was higher than hydrogenotrophic methanogenesis, which is unusual for cold seep sediments. Interestingly, acetate porewater concentrations were extremely high in the AMV sediments. This might be the result of organic matter cracking in deeper hotter sediment layers. Methane was also produced from hexadecanes. For the most part, the methanogenic community diversity was in accordance with the depth distribution of the H2/CO2 and acetate methanogenesis. These results demonstrate the importance of methanogenic communities in the centres of marine mud volcanoes.
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