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7716333 
Journal Article 
Methane release from sediment seeps to the atmosphere is counteracted by highly active Methylococcaceae in the water column of deep oligotrophic Lake Constance 
Bornemann, M; Bussmann, I; Tichy, L; Deutzmann, J; Schink, B; Pester, M 
2016 
Yes 
FEMS Microbiology Ecology
ISSN: 0168-6496
EISSN: 1574-6941 
92 
8 
English 
27267930 
WOS:000383230500019 
Methane emissions from freshwater environments contribute substantially to global warming but are under strong control of aerobic methane-oxidizing bacteria. Recently discovered methane seeps (pockmarks) in freshwater lake sediments have the potential to bypass this control by their strong outgassing activity. Whether this is counteracted by pelagic methanotrophs is not well understood yet. We used a (3)H-CH4-radiotracer technique and pmoA-based molecular approaches to assess the activity, abundance and community structure of pelagic methanotrophs above active pockmarks in deep oligotrophic Lake Constance. Above profundal pockmarks, methane oxidation rates (up to 458 nmol CH4 l(-1) d(-1)) exceeded those of the surrounding water column by two orders of magnitude and coincided with maximum methanotroph abundances of 0.6% of the microbial community. Phylogenetic analysis indicated a dominance of members of the Methylococcaceae in the water column of both, pockmark and reference sites, with most of the retrieved sequences being associated with a water-column specific clade. Communities at pockmark and reference locations also differed in parts, which was likely caused by entrainment of sediment-hosted methanotrophs at pockmark sites. Our results show that the release of seep-derived methane to the atmosphere is counteracted by a distinct methanotrophic community with a pronounced activity throughout bottom waters.