Anaerobic oxidation of methane mediated by microbial extracellular respiration

Abstract

Summary Anaerobic oxidation of methane (AOM) can be microbially mediated by the reduction of different terminal electron acceptors. AOM coupled to reduction of sulfate, manganese/iron oxides, humic substances, selenate, arsenic and other artificial extracellular electron acceptors are recognized as processes associated with microbial extracellular respiration. In these processes, methane‐oxidizing archaea transfer electrons to external electron acceptors or to interdependent microbial species, which are mechanistically dependent on versatile extracellular electron transfer (EET) pathways. This review compiles recent progress in the research of electromicrobiology of AOM based on the catalogue of different electron acceptors. Naturally distributed and artificially constructed EET‐mediated AOM is summarized, with the discussion of their environmental importance and application potentials. The diversity of responsible microorganisms involved in EET‐mediated AOM is discussed with both methane‐oxidizing archaea and their putative bacterial partners. More importantly, the review highlights progress and deficiencies in our understanding of EET pathways in EET‐mediated AOM, raising open research questions for future research.

Significance of anaerobic oxidation of methane (AOM) in mitigating methane emission from major natural and anthropogenic sources: a review of AOM rates in recent publications

“…Instead of detailing the various reaction pathways, reaction thermodynamics, biochemical mechanisms, microbial physiology, and the various implications in natural and engineered systems like other reviews, 7,9,[35][36][37][38][39][40][41][42][43][44] this review article concentrates on recently published AOM rates in the literature (ca. 2010-2021).…”

Electrically Conductive Biofilms Assembled by Magnetite in Anaerobic Oxidation of Methane Coupled to Debromination/Denitrification

“…17−19 For instance, microbial reduction of Cr(VI), Se(VI), and As(V) depends on the specific reductases that are unable to be synthesized by ANME archaea/methanogens, which requires the electron-accepting partners to transfer the electrons derived from methane oxidation to these compounds. 17 Electron transfer between ANME archaea/methanogens and their electron-accepting partners has been early described as a diffusive exchange of dissolved electron-carrying molecules, such as hydrogen, formate, and acetate (Figure 1A). 17,18 This is supported by the fact that some ANME archaea contain the genes encoding hydrogen, formate, and acetate synthetases 20 as well as the observations that these molecules are accumulated within syntrophic consortia.…”

“…Anaerobic oxidation of methane (AOM) via reverse methanogenesis proceeded by anaerobic methanotrophic (ANME) archaea or methanogens has been recently recognized as an important process for greenhouse gas emission control and water environmental remediation in paddy soils, marine sediments, freshwater habitats, and artificial bioreactors. , Until now, electron acceptors for AOM have been described as nitrate, sulfate, perchlorate, bromate, selenate, antimonate, metals, − humic substances, biochar, and electrodes . Although AOM coupled to the reduction of sulfate, nitrate, Fe­(III)/Mn­(IV) oxides, , and electrodes has been identified to be proceeded independently by ANME archaea/methanogens, AOM mediated by a syntrophic consortium comprised of ANME archaea/methanogens and their electron-accepting partners plays a critical role in water environmental remediation. − For instance, microbial reduction of Cr­(VI), Se­(VI), and As­(V) depends on the specific reductases that are unable to be synthesized by ANME archaea/methanogens, which requires the electron-accepting partners to transfer the electrons derived from methane oxidation to these compounds …”

“…Electron transfer between ANME archaea/methanogens and their electron-accepting partners has been early described as a diffusive exchange of dissolved electron-carrying molecules, such as hydrogen, formate, and acetate (Figure A). , This is supported by the fact that some ANME archaea contain the genes encoding hydrogen, formate, and acetate synthetases as well as the observations that these molecules are accumulated within syntrophic consortia. , Trafficking in diffusive exchange of these molecules is a slow way. , If the consumption of these molecules fails to keep up with the production, the metabolic activity of AOM will shut down.…”

Heme Hopping Falls Short: What Explains Anti-Arrhenius Conductivity in a Multi-heme Cytochrome Nanowire?

“…Coupling the reduction of microbes or minerals in the extracellular space with intracellular oxidative metabolism constitutes an ancient and widespread respiratory strategy. [4][5][6][7] The electrical circuits established between microbes and minerals, if better understood, can elucidate the biogeochemical evolution of the planet, [8][9][10][11][12][13] the role of the microbiome in human health and disease, [14][15][16][17] as well as templates [18][19][20][21] for the design of bioelectronic technologies. [21][22][23][24][25][26][27][28][29][30][31][32][33][34] Microbes can electrically 'plug-in' to their environments through direct contact with cell-surface proteins, outer-membrane vesicles, filamentous appendages, or molecular shuttles.…”