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Methanogens and MIC
Published in Kenneth Wunch, Marko Stipaničev, Max Frenzel, Microbial Bioinformatics in the Oil and Gas Industry, 2021
Timothy J. Tidwell, Zachary R. Broussard
Some methanogens can also reverse the methanogenesis pathway to oxidize methane, where mcr serves as the first step. Anaerobic methane-oxidizing archaea (ANME) are responsible for the anaerobic oxidation of methane (AOM) (Shima and Thauer 2005). AOM is catalyzed via a modified, reverse methanogenesis pathway, but only during net methane production or trace methane oxidation (TMO). TMO produces CO2 in trace amounts relative to the methane produced. The Gibbs free energy change of the forward mcr reaction under standard conditions is −30 kJ mol−1 (Scheller, et al. 2010). Therefore, the reverse mechanism is endergonic under standard conditions, but in high methane concentrations, the reaction can become endergonic. Net AOM can also be exergonic when coupled to an external electron acceptor such as sulfate, nitrate, or metal oxides (Timmers, et al. 2017). No studies show that methanogens can conserve energy from TMO, even under thermodynamically favorable conditions. Although more questions remain about these divergent mcrA variants’ functions, it seems the most likely role of AOM is a mechanism to deal with back flux of individual enzymes of the methanogenic pathway (Holler, et al. 2011).
Literature review
Published in Tejaswini Eregowda, Anaerobic treatment and resource recovery from methanol rich waste gases and wastewaters, 2019
Anaerobic oxidation of methane (AOM) is a natural phenomenon occurring in deep marine environments with methane seepage. AOM is mediated by a consortium of archaea called anaerobic methanotrophs (ANME) and sulphate reducing bacteria (SRB) (Cassarini et al., 2017). As methane diffuses upwards to shallower sulfate-penetrated sediments, more than 90% of the methane is consumed by ANME, corresponding to around 7–25% of the total global methane production (Bousquet et al., 2006; Mueller et al., 2015). Anaerobic oxidation of methane (AOM) facilitated by ANME can capture up to 300 million metric tonnes of methane per year and plays a key role in regulating the methane global flux and carbon cycle (Soo et al., 2016).
Pressure Sensitivity of ANME-3 Predominant Anaerobic Methane Oxidizing Community from Coastal Marine Lake Grevelingen Sediment
Published in Chiara Cassarini, Anaerobic Oxidation of Methane Coupled to the Reduction of Different Sulfur Compounds as Electron Acceptors in Bioreactors, 2019
Anaerobic oxidation of methane (AOM) coupled to sulfate reduction is mediated by, respectively, anaerobic methanotrophic archaea (ANME) and sulfate reducing bacteria (SRB). When a microbial community, obtained from the coastal marine Lake Grevelingen sediment and containing ANME-3 as the most abundant type of ANME, was incubated under a pressure gradient (0.1-40 MPa) for 77 days, ANME-3 appeared to be more pressure sensitive than the SRB. ANME-3 activity was higher at lower (0.1, 0.45 MPa) over higher (10, 20 and 40 MPa) CH4 total pressures. Moreover, the sulfur metabolism was shifted upon changing the incubation pressure: SRB of the Desulfobacterales were more enriched at elevated pressures than the Desulfubulbaceae. This study provides evidence that ANME-3 can be constrained at shallow environments, despite the scarce bioavailable energy, because of its pressure sensitivity. Besides, the association between ANME-3 and SRB can be steered by changing solely the incubation pressure.
Depositional rate, grain size and magnetic mineral sulfidization in turbidite sequences, Hikurangi Margin, New Zealand
Published in New Zealand Journal of Geology and Geophysics, 2022
Atsushi Noda, Annika Greve, Adam Woodhouse, Martin Crundwell
For marine sediments accompanying high organic carbon, such as trench-wedge deposits along subduction margins, diagenetic reactions from magnetic iron oxides to iron sulfides (e.g. greigite and pyrite) tend to depend on the availability of sulfate and organic carbon (e.g. Sweeney and Kaplan 1973; Larrasoaña et al. 2007; Rickard and Luther 2007; Fu et al. 2008; Rickard 2012; Roberts 2015). Sediments below the seafloor are a sulfidic environment where reduction of sulfate () due to bacterial degradation of organic matter releases hydrogen sulfide (H2S or HS−1) (sulfate zone in Figure 14). Especially, the sulfate–methane transition zone (SMTZ) is characterised by a zone where anaerobic oxidation of methane (AOM) efficiently produces hydrogen sulfide from the reaction between methane and sulfate ions (AOM zone in Figure 14). The reaction of diffusing hydrogen sulfide with dissolved ferrous iron ion (Fe2+) formed from the reduction of ferric iron minerals (e.g. magnetite) with organic carbon produce iron monosulfides (FeS) during the earliest diagenesis (e.g. Berner 1970, 1984; Fu et al. 2008; Volvoikar et al. 2020).
Genetic link between Miocene seafloor methane seep limestones and underlying carbonate conduit concretions at Rocky Knob, Gisborne, New Zealand
Published in New Zealand Journal of Geology and Geophysics, 2019
Campbell S. Nelson, Kathleen A. Campbell, Stephanie L. Nyman, Jens Greinert, David A. Francis, Steven D. Hood
Methane seep carbonate deposits form as a by-product of sulphate-dependent, archaeal, anaerobic oxidation of methane (AOM) in marine sediments (Aharon 2000). The driver relates to hydrocarbon seepage at or just beneath the seafloor in fluid-overpressured sedimentary basins where chemosynthesis-based communities oxidise dissolved H2S and CH4 to provide energy for a food web flourishing in an otherwise harsh physico-chemical setting (Conti and Fontana 1999; Judd and Hovland 2007). Chemically precipitated microcrystalline calcite or aragonite to coarsely crystalline aragonite and/or calcite with highly negative carbon isotope values (typically in the range −60‰ to −20‰ VPDB; Cavagna et al. 1999; Judd and Hovland 2007), referred to collectively as methane-derived authigenic carbonate, or MDAC, are major components of these seafloor seep deposits, along with any included skeletal remains of both chemosynthetic and non-chemosynthetic taxa (Sibuet and Olu 1998; Greinert et al. 2001; Campbell 2006; Campbell et al. 2008, 2010). The fossiliferous MDAC deposits that form at or just beneath the sediment-water interface are morphologically extremely diverse in shape and size, and include crusts, slabs and blocks formed at or within the uppermost surficial seabed sediment, or low to higher relief build-ups (chemoherms) formed at and above the seafloor (e.g. Gaillard et al. 1992; Roberts and Aharon 1994; Conti and Fontana 1999; Reitner et al. 2005; Judd and Hovland 2007; Bayon et al. 2013; Blumenberg et al. 2015).
Lateral variations and vertical structure of the microbial methane cycle in the sediment of Lake Onego (Russia)
Published in Inland Waters, 2019
Camille Thomas, Victor Frossard, Marie-Elodie Perga, Natacha Tofield-Pasche, Hilmar Hofmann, Nathalie Dubois, Natalia Belkina, Mariya Zobkova, Serge Robert, Emilie Lyautey
Within Methanomicrobia, 51 OTUs were grouped into a poorly constrained cluster named the Onego group (Fig. 7). Closely related sequences were associated with the former Fen cluster (Supplemental Material) and were classified either into unclassified Methanoregulaceae, unclassified Methanomicrobiales, or unclassified Euryarchaeota. Other sequences were attributed to Methanosarcinaceae (8 OTUs) and were identified mainly at site P2. Five OTUs seem to be related to sequences identified as members of the Methanolinea genus. The rest of the affiliated Methanomicrobia sequences grouped with members of the Methanocellales order (4 OTUs). The 5 remaining OTUs grouped within a Methanobacteriales group and were retrieved mainly from the rare OTUs pool (PP). In silico T-RFLP and site-specific cloning libraries allowed us to attribute site occurrence to 51 OTUs (color-coded in Fig. 6). Five OTUs were identified at site P1 only, all of which belonged to the Onego cluster (5 OTUs). Ten OTUs from the Onego cluster, 5 Methanosarcina, 1 Methanocella, and 1 Methanobacteria were found at P2 only. Site P3 specific OTUs were attributed to the Onego cluster (3 OTUs) and to Methanolinea (1 OTU). Based on cloning results, phylogenetic distance measured by Unifrac was found to be higher between P1 and P2 (0.68) or between P1 and P3 (0.64) than between P2 and P3 (0.59). All measured distances were found to be significant (p < 0.001). Finally, note that no anaerobic oxidation of methane (ANME) sequence was identified.