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Physiology and Distribution of Anaerobic Oxidation of Methane by Archaeal Methanotrophs
Published in Susma Bhattarai Gautam, Performance Assessment and Enrichment of Anaerobic Methane Oxidising Microbial Communities from Marine Sediments in Bioreactors, 2018
Samples from marine habitats around the globe have been retrieved through the years, and extensive molecular analysis of such samples have yielded a great number of 16S rRNA and mcrA gene sequences of the archaeal microorganisms inhabiting those sites. The mcrA gene encodes the alpha-subunit of the methyl coenzyme-M reductase (MCR), which is catalyzing the last step in methanogenesis, and it is also thought to catalyze the oxidation of CH4, since MCR can function in reverse methanogenesis (Kruger et al., 2003; Scheller et al., 2010). Upon phylogenetic analysis based on 16S rRNA (Figure 2.3A) and mcrA (Figure 2.3B) genes, the three major groups of ANME were identified. ANME-1 is further subgrouped into ANME-1a and ANME-1 b. ANME-2 is divided into four subgroups i.e. ANME-2a, ANME-2b, ANME-2c and ANME-2d, whereas, so far no subgroups of ANME-3 have been defined (Figure 2.3). The mcrA genes phylogeny of the various archaeal orders closely parallels that of the 16S rRNA genes (Figure 2.3).
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
Methanogens are abundant in a wide variety of anaerobic environments, where they catalyze the terminal step in the anaerobic food chain by converting methanogenic substrates, such as CO2, acetate, and other C1-compunds, into methane. The complexity of methanogenesis pathways suggests an ancient monophyletic origin of methanogens, a hypothesis supported by phylogenetic analyses based upon DNA sequences. The only enzyme present in all types of methanogenesis is methyl-coenzyme M reductase (Mcr), a Ni-corrinoid protein catalyzing the last step of methyl group reduction to methane (Berghuis, et al. 2019).
Nanoparticles in Methane Production from Anaerobic Digesters
Published in Madan L. Verma, Nanobiotechnology for Sustainable Bioenergy and Biofuel Production, 2020
Efraín Reyes Cruz, Lilia Ernestina Montañez Hernández, Inty Omar Hernández De Lira, Nagamani Balagurusamy
Another key enzyme that impacts methane production is methyl-coenzyme M reductase (MCR). This enzyme is the one that catalyzes the formation of methane in all methanogenesis pathways, and it requires the binding of a prosthetic group, coenzyme F430, which contains Ni. It has been previously demonstrated that Ni limitation greatly impacts the distribution and activity of MCR (Ermler et al. 1997, Ferry 1999, Takano et al. 2013), therefore small amounts of this metal must be present in order to guarantee methanogenic activity.
Enhancing integrated denitrifying anaerobic methane oxidation and Anammox processes for nitrogen and methane removal: A review
Published in Critical Reviews in Environmental Science and Technology, 2023
Yan Chen, Guangming Jiang, Muttucumaru Sivakumar, Jiangping Wu
There are two different metabolic mechanisms for DAMO archaea and DAMO bacteria. DAMO archaea drive the process through reverse methanogenesis (Haroon et al., 2013; Wu et al., 2011). This reaction is catalyzed by a homologue of methyl-coenzyme M reductase (methane activating enzyme, mcr). Indeed, DAMO archaea were reported to contain a high concentration of mcr. This nickel enzyme, a classical molecular biomarker of methanogenesis, catalyzes the methane-oxidizing step (Ding et al., 2015; Hallam et al., 2004; Timmers et al., 2017). DAMO bacteria are capable of producing O2 via the intra-aerobic pathway other than reverse methanogenesis. The intracellularly produced O2 would be partly (3/4) used for methane activation (Wu et al., 2011). It employs a particulate high concentration of methane monooxygenase (pMMO) for the activation of methane into methanol. This makes it possible to use one of the encoding genes (pmoA) as a functional biomarker for their specific detection in the environment (Ettwig et al., 2010; Welte et al., 2016).
Microbial and functional characterization of granulated sludge from full-scale UASB thermophilic reactor applied to sugarcane vinasse treatment
Published in Environmental Technology, 2022
Franciele Pereira Camargo, Isabel Kimiko Sakamoto, Tiago Palladino Delforno, Cédric Midoux, Iolanda Cristina Silveira Duarte, Edson Luiz Silva, Ariane Bize, Maria Bernadete Amâncio Varesche
The K14128 and K14126 were both related only with the genus Methanothermobacter, since the enzyme F420-non-reducing hydrogenase small and large subunits are related only with hydrogenotrophyc methanogenesis (Equation (19)). Besides that, the methyl-coenzyme M reductase gamma subunit (K00402) is a transferase which catalysis the last methanogenesis step, where the biological methane production occurs. Among the genera commonly related with the K00402, were Methanosarcina and Methanothermobacter [73–75]. The K00193 can be associated with the synthesis of methyl-Co (III) Fe-S corrinoid protein (CH3-CO(III)FeSP), using the Co(I) corrinoid Fe-S protein and acetyl-CoA. After this conversion, the enzymes acetyl-CoA decarbonylase/synthase (K00194 and K00197) act in the conversion of the CH3-CO(III)FeSP to Co(I) corrinoid Fe-S protein and 5-methyl tetrahydro sarcina pterin (5-Methyl-H4SPT).
Effects of livestock manure properties and temperature on the methanogen community composition and methane production during storage
Published in Environmental Technology, 2020
Guang Guo, Yongxing Chen, Fang Tian, Zhenduo Gao, Changxiong Zhu, Chong Liu
In this study, based on a comparison of two livestock slurries (cattle and swine), an extensive molecular analysis using 16S rRNA amplicon sequencing and quantitative PCR was conducted to elucidate (i) the effect of slurry properties and temperature on the methanogen community and methane emissions, and (ii) how methanogens respond to environmental factors that drive methane production. Here, the transcripts of alpha subunit of methyl coenzyme M reductase (mcrA) gene responsible for converting carbon dioxide/hydrogen into methane are qualified, and the mcrA transcripts/gene ratio is used to act as an indicator of methanogenesis [14]. Our objectives were to obtain a mechanistic understanding of the effects of temperature and slurry properties on differential methane emissions and the microbial response during slurry storage.