Open AccessEvidence for anaerobic oxidation of methane in sediments of a freshwater system (Lago di Cadagno)
Author(s) -
Schubert Carsten J.,
Vazquez Francisco,
LösekannBehrens Tina,
Knittel Katrin,
Tonolla Mauro,
Boetius Antje
Publication year - 2011
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2010.01036.x
Subject(s) - anaerobic oxidation of methane , deltaproteobacteria , sulfate , carbonate , methane , sediment , environmental chemistry , microbial mat , methanogenesis , sulfate reducing bacteria , biology , chemistry , ecology , 16s ribosomal rna , bacteria , paleontology , cyanobacteria , organic chemistry , gammaproteobacteria
Anaerobic oxidation of methane (AOM) has been investigated in sediments of a high alpine sulfate‐rich lake. Hot spots of AOM could be identified based on geochemical and isotopic evidence. Very high fractionation of methane (α=1.031) during oxidation was observed in the uppermost sediment layers, where methane is oxidized most likely with sulfate‐containing bottom waters. However, we could not exclude that other electron acceptors such as iron, or manganese might also be involved. Light carbon isotope values (δ 13 C=−10‰ vs. Vienna Pee Dee Belemnite [VPDB]) of sedimentary carbonates at 16–20 cm sediment depth are indicative of a zone where methane was oxidized and the resulting bicarbonate ions were used for carbonate precipitation. 16S rRNA gene analysis revealed the presence of sequences belonging to the marine benthic groups B, C, and D and to the recently described clade of AOM‐associated archaea (AAA). Catalyzed reporter deposition‐FISH analysis revealed a high abundance of Deltaproteobacteria , especially of free‐living sulfate‐reducing bacteria of the Desulfosarcina/Desulfococcus branch of Deltaproteobacteria in the AOM zone. Here, loose aggregations of AAA cells were found, suggesting that AAA might be responsible for oxidation of methane in Lake Cadagno sediments.