Effects of alternative electron acceptors on the activity and community structure of methane-producing and consuming microbes in the sediments of two shallow boreal lakes.
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Rissanen AJ, Karvinen A, Nykänen H, Peura S, Tiirola M, Mäki A, Kankaala P
FEMS Microbiol. Ecol. 93 (7) - [2017-07-01; online 2017-06-24]
The role of anaerobic CH4 oxidation in controlling lake sediment CH4 emissions remains unclear. Therefore, we tested how relevant EAs (SO42-, NO3-, Fe3+, Mn4+, O2) affect CH4 production and oxidation in the sediments of two shallow boreal lakes. The changes induced to microbial communities by the addition of Fe3+ and Mn4+ were studied using next-generation sequencing targeting the 16S rRNA and methyl-coenzyme M reductase (mcrA) genes and mcrA transcripts. Putative anaerobic CH4-oxidizing archaea (ANME-2D) and bacteria (NC 10) were scarce (up to 3.4% and 0.5% of archaeal and bacterial 16S rRNA genes, respectively), likely due to the low environmental stability associated with shallow depths. Consequently, the potential anaerobic CH4 oxidation (0-2.1 nmol g-1dry weight (DW)d-1) was not enhanced by the addition of EAs, nor important in consuming the produced CH4 (0.6-82.5 nmol g-1DWd-1). Instead, the increased EA availability suppressed CH4 production via the outcompetition of methanogens by anaerobically respiring bacteria and via the increased protection of organic matter from microbial degradation induced by Fe3+ and Mn4+. Future studies could particularly assess whether anaerobic CH4 oxidation has any ecological relevance in reducing CH4 emissions from the numerous CH4-emitting shallow lakes in boreal and tundra landscapes.
PubMed 28637304
DOI 10.1093/femsec/fix078
Crossref 10.1093/femsec/fix078
pii: 3868356