Anaerobic Microbial Communities and Processes Involved in the Methane Cycle in Freshwater Lakes-a Focus on Lake Pavin

Lake Sediments From Littoral and Profundal Zones are Heterogeneous but Equivalent Sources of Methane Produced by Distinct Methanogenic Communities—A Case Study From Lake Remoray

“…However, aerobic methane oxidation is more likely to occur in the water column, as oxygen diffusion in the sediment is expected to be low, aerobic methane oxidation may not be the only pathway involved in Lake Remoray sediment, especially in the deeper area of the lake and/or deeper layers of the sediment column, even though methanotrophs are also active in anoxic conditions (Oswald et al., 2016). Anaerobic oxidation of methane is coupled with nitrate, sulfate, or iron reduction (Lehours et al., 2016). The occurrence of the anaerobic methanotrophs Ca.…”

“…Methanotrophs oxidize methane into carbon dioxide under both anaerobic and aerobic conditions (Bhattarai et al, 2019;Kang et al, 2019) with efficiencies ranging from 30% to 99% in lake ecosystems (Bastviken et al, 2008). In lakes, methanogenesis mainly takes place in the sediment and in the deeper water column layers under temporary or permanent anoxic conditions (Bastviken et al, 2008;Lehours et al, 2016;Liu et al, 2017;Peeters et al, 2019) although methanogenesis in oxic conditions has been reported (i.e., the methane paradox, Bižić et al [2020]; Grossart et al [2011]; Wang et al [2021]). Methane oxidation is carried out aerobically by methanotrophic bacteria or anaerobically in the presence of sulfates or nitrates as terminal electron acceptors by methanotrophic Archaea (Borrel et al, 2011).…”

Spatial heterogeneity of methane concentration, diffusion and production potential, and methanogen community abundance and diversity in sediments from Lake Remoray (France)

“…The analysis of the carbon isotopic signature of methane would have helped to quantify the contribution of CH 4 oxidation [19] to diffusion mitigation. Methane oxidation can occur under both aerobic and anaerobic conditions, and is a metabolic pathway supported by both archaeal and bacterial microbial species [12]. Here, aerobic methanotrophy community abundance, assessed by quantifying relative abundance of the pmoA gene, represented only 0.01% to 0.03 % of the sediment bacterial community.…”

“…However, as oxygen diffusion in the sediment compartment is expected to be low, aerobic methane oxidation may not be the only pathway involved in Lake Remoray, especially in the deeper area of the lake and/or deeper layers of the sediment column, even though methanotrophs are also active in anoxic conditions [65]. Anaerobic oxidation of methane is coupled with nitrate, sulphate or iron reduction [12]. The occurrence of the anaerobic methanotrophs Ca.…”

“…Microbial actors of the methane cycle are the methanogenic archaea, which are involved under anoxic conditions in the nal stage of reducing organic matter (OM) into methane [8], and methanotrophic organisms (archaea and bacteria) that oxidize, with e ciencies ranging from 30% to 99% in lake ecosystems [9],) methane under both anaerobic and aerobic conditions into carbon dioxide [10,11]. In lakes, methanogenesis mainly takes place in the sediment compartment and in the deeper water column layers under temporary or permanent anoxic conditions [12]. Methane oxidation occurs aerobically when carried out by methanotrophic bacteria or anaerobically in the presence of sulfates or nitrates as terminal electron acceptors when carried out by methanotrophic Archaea [13].…”