Topic
Methanogen
About: Methanogen is a research topic. Over the lifetime, 1146 publications have been published within this topic receiving 48254 citations.
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TL;DR: In this article , the authors used sediment slurry incubations under controlled conditions to elucidate the electron acceptors and microorganisms that are involved in the AOM process over the long term (∼ 18 months).
Abstract: Abstract. Anaerobic oxidation of methane (AOM) is among the main processes limiting
the release of the greenhouse gas methane from natural environments.
Geochemical profiles and experiments with fresh sediments from Lake Kinneret
(Israel) indicate that iron-coupled AOM (Fe-AOM) sequesters 10 %–15 % of
the methane produced in the methanogenic zone (>20 cm sediment
depth). The oxidation of methane in this environment was shown to be
mediated by a combination of mcr-gene-bearing archaea and pmoA-gene-bearing aerobic
bacterial methanotrophs. Here, we used sediment slurry incubations under
controlled conditions to elucidate the electron acceptors and microorganisms
that are involved in the AOM process over the long term (∼ 18 months). We monitored the process with the addition of 13C-labeled
methane and two stages of incubations: (i) enrichment of the microbial
population involved in AOM and (ii) slurry dilution and manipulations,
including the addition of several electron acceptors (metal oxides, nitrate,
nitrite and humic substances) and inhibitors (2-bromoethanesulfonate,
acetylene and sodium molybdate) of methanogenesis, methanotrophy and sulfate
reduction and sulfur disproportionation. Carbon isotope measurements in the
dissolved inorganic carbon pool suggest the persistence of AOM, consuming
3 %–8 % of the methane produced at a rate of 2.0 ± 0.4 nmol per gram of dry sediment per day. Lipid carbon isotopes and metagenomic analyses
point towards methanogens as the sole microbes performing the AOM process by
reverse methanogenesis. Humic substances and iron oxides, although not sulfate,
manganese, nitrate or nitrite, are the likely electron acceptors used for
this AOM. Our observations support the contrast between methane oxidation
mechanisms in naturally anoxic lake sediments, with potentially co-existing
aerobes and anaerobes, and long-term incubations, wherein anaerobes prevail.
3 citations
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TL;DR: Two methanogen strains were isolated from methane fermenting liquor by using Hungate obligate anaerobic technique with methanol,formate and acetate as carbon and energy source and indicated that they were sensitive to the change of pH value and temperature.
Abstract: Two methanogen strains were isolated from methane fermenting liquor by using Hungate obligate anaerobic technique with methanol,formate and acetate as carbon and energy source.They emit blue-green fluorescence when observed by fluorogenic microscope.Their colonies in roll tubes are irregular round and white or a little yellow.In addition,the effect of different pH value and temperature of the growth of the methanogen was studied.The methanogen's optimum growth pH value is 7.0 and can range from 6.5 to 8.0,and the optimum growth temperature is 35 ℃,the results indicated that they were sensitive to the change of pH value and temperature,so a steady circumstance is needed.
3 citations
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TL;DR: In this article , a multitrophic methanogen, Methanosarcina barkeri DSM 800, was cultured with acetate, H2/CO2, and methanol to evaluate the influence of ammonia on different methanogenic pathways.
3 citations
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TL;DR: Li et al. as mentioned in this paper used anaerobic glove chamber as the experimental platform to enrich and cultivate active methanogen flora from freshly collected brown coal samples from Zhaotong basin,Yunnan Province, China.
3 citations
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TL;DR: In this article, it was shown that the ancestor of all methane metabolizers was an autotrophic H2/CO2 methanogen that could perhaps use methanol but not oxidize alkanes.
Abstract: Methane metabolism is among the hallmarks of Archaea, originating very early in their evolution. Other than its two main complexes, methyl-CoM reductase (Mcr) and tetrahydromethanopterin-CoM methyltransferase (Mtr), there exist other genes called "methanogenesis markers" that are believed to participate in methane metabolism. Many of them are Domains of Unknown Function. Here we show that these markers emerged together with methanogenesis. Even if Mcr is lost, the markers and Mtr can persist resulting in intermediate metabolic states related to the Wood-Ljungdahl pathway. Beyond the markers, the methanogenic ancestor was hydrogenotrophic, employing the anaplerotic hydrogenases Eha and Ehb. The selective pressures acting on Eha, Ehb, and Mtr partially depend on their subunits9 membrane association. Integrating the evolution of all these components, we propose that the ancestor of all methane metabolizers was an autotrophic H2/CO2 methanogen that could perhaps use methanol but not oxidize alkanes. Hydrogen-dependent methylotrophic methanogenesis has since emerged multiple times independently, both alongside a vertically inherited Mcr or from a patchwork of ancient transfers. Through their methanogenesis genomic remnants, Thorarchaeota and two newly reconstructed order-level lineages in Archaeoglobi and Bathyarchaeota act as metabolically versatile players in carbon cycling of anoxic environments across the globe.
3 citations