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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: Comparison of these gene sequences indicates that methanogenesis gene organisation is conserved within the Methanobacteriales, and the genome of M. ruminantium contains a prophage sequence with distinct functional modules encoding phage integration, DNA replication and packaging, capsid proteins and lysis functions.
Abstract: Methane is produced in the foregut (rumen) of ruminants by methanogens, which act as terminal reducers of carbon in the rumen system. The multistep methanogenesis pathway is well elucidated, mainly from the study of non-rumen methanogens, but the adaptations that allow methanogens to grow and persist in the rumen are not well understood. The Pastoral Greenhouse Gas Research Consortium is sequencing the genome of Methanobrevibacter ruminantium, a prominent methanogen in New Zealand ruminants, as part of a project to mitigate greenhouse gases. The genome is ~3.0 Mb in size with a guanine–cytosine (GC) content of 33.68%. All of the components of the methanogenesis pathway have been identified and comparison of these gene sequences with those from Methanothermobacter thermoautotrophicus and Methanosphaera stadtmanae indicates that methanogenesis gene organisation is conserved within the Methanobacteriales. The genome of M. ruminantium contains a prophage sequence (designated φmru) with distinct functional modules encoding phage integration, DNA replication and packaging, capsid proteins and lysis functions. A low GC region found at the distal end of the phage sequence harbours a putative DNA restriction/modification system which might provide additional protection against foreign DNA. The genome also contains many large surface proteins with characteristics that indicate that they may mediate association with other rumen microbes. Approximately half of the genes identified within the genome have no known function. Determining the function of these new genes will assist in defining the role of M. ruminantium in methane formation in the rumen and help identify means to control methane emissions from ruminant animals.

34 citations

Journal ArticleDOI
TL;DR: The stoichiometric conversion of acetate to CH4 in the absence of added H suggests that all the CH4 is derived most probably from the Me group of acetates, which may help to improve the performance of biogas digesters.
Abstract: Isolation and characterization of a fast-growing filament-forming methanogen (Methanothrix soehngenii strain VNBF) which uses acetate as the sole energy source for growth are reported. The stoichiometric conversion of acetate to CH4 [74-82-8] in the absence of added H suggests that all the CH4 is derived most probably from the Me group of acetate. The strain VNBF may be playing a key role in methanogenesis from org. wastes. Its high efficiency of CH4 prodn. may help to improve the performance of biogas digesters.

34 citations

Journal ArticleDOI
TL;DR: The aeration stress affected the acetotrophic methanogens more than the hydrogenotrophic ones, thus explaining the metabolism of the intermediates of cellulose degradation under the different incubation conditions.
Abstract: Two cellulose-fermenting methanogenic enrichment cultures originating from rice soil, one at 15 degrees C with Methanosaeta and the other at 30 degrees C with Methanosarcina as the dominant acetoclastic methanogen, both degraded cellulose anaerobically via propionate, acetate and H2 to CH4. The degradation was a two-stage process, with CH4 production mainly from H2/CO2 and accumulation of acetate and propionate during the first, and methanogenic consumption of acetate during the second stage. Aeration stress of 12, 24, 36 and 76 h duration was applied to these microbial communities during both stages of cellulose degradation. The longer the aeration stress, the stronger the inhibition of CH4 production at both 30 degrees C and 15 degrees C. The 72 h stressed culture at 30 degrees C did not fully recover. Aeration stress at 30 degrees C exerted a more pronounced effect, but lasted for a shorter time than that at 15 degrees C. The aeration stress was especially effective during the second stage of fermentation, when consumption of acetate (and to a lesser extent propionate) was also increasingly inhibited as the duration of the stress increased. The patterns of CH4 production and metabolite accumulation were consistent with changes observed in the methanogenic archaeal community structure. Fluorescence in situ hybridization showed that the total microbial community at the beginning consisted of about 4% and 10% archaea, which increased to about 50% and 30% during the second stage of cellulose degradation at 30 degrees C and 15 degrees C respectively. Methanosarcina and Methanosaeta species became the dominant archaea at 30 degrees C and 15 degrees C respectively. The first round of aeration stress mainly reduced the non-Methanosarcina archaea (30 degrees C) and the non-Methanosaeta archaea (15 degrees C). Aeration stress also retarded the growth of Methanosarcina and Methanosaeta at 30 degrees C and 15 degrees C respectively. The longer the stress, the lower was the percentage of Methanosarcina cells to total microbial cells after the first stress at 30 degrees C. A later aeration stress decreased the population of Methanosarcina (at 30 degrees C) in relation to the duration of stress, so that non-Methanosarcina archaea became dominant. Hence, aeration stress affected the acetotrophic methanogens more than the hydrogenotrophic ones, thus explaining the metabolism of the intermediates of cellulose degradation under the different incubation conditions.

34 citations

Journal ArticleDOI
TL;DR: Acyclic phytanyl diether glycerol and biphytanyl ether lipids have been quantified in two modern swamp sediment cores in concentrations ranging up to 360 μg/ml porewater as discussed by the authors.

34 citations

Journal ArticleDOI
TL;DR: The first predictive model of global gene regulation of methanogenesis in a hydrogenotrophic methanogen, Methanococcus maripaludis, is presented and the EGRIN-predicted role of two novel transcription factors in the regulation of phosphate-dependent repression of formate dehydrogenase is validated.
Abstract: Methanogens catalyze the critical methane-producing step (called methanogenesis) in the anaerobic decomposition of organic matter. Here, we present the first predictive model of global gene regulation of methanogenesis in a hydrogenotrophic methanogen, Methanococcus maripaludis. We generated a comprehensive list of genes (protein-coding and noncoding) for M. maripaludis through integrated analysis of the transcriptome structure and a newly constructed Peptide Atlas. The environment and gene-regulatory influence network (EGRIN) model of the strain was constructed from a compendium of transcriptome data that was collected over 58 different steady-state and time-course experiments that were performed in chemostats or batch cultures under a spectrum of environmental perturbations that modulated methanogenesis. Analyses of the EGRIN model have revealed novel components of methanogenesis that included at least three additional protein-coding genes of previously unknown function as well as one noncoding RNA. We discovered that at least five regulatory mechanisms act in a combinatorial scheme to intercoordinate key steps of methanogenesis with different processes such as motility, ATP biosynthesis, and carbon assimilation. Through a combination of genetic and environmental perturbation experiments we have validated the EGRIN-predicted role of two novel transcription factors in the regulation of phosphate-dependent repression of formate dehydrogenase-a key enzyme in the methanogenesis pathway. The EGRIN model demonstrates regulatory affiliations within methanogenesis as well as between methanogenesis and other cellular functions.

33 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202379
2022139
202189
202067
201974
201863