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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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Journal ArticleDOI
01 Aug 2017-Geoderma
TL;DR: In this paper, the authors analyzed two freshwater and two brackish (oligohaline) marshes in a subtropical estuary, where they assessed methanogenic community structure and abundance by molecular cloning, sequencing, and quantitative PCR methods.

37 citations

Journal ArticleDOI
TL;DR: The genome-enabled reconstructed metabolisms reported here have significance to diverse anaerobic communities and have led to proposed substrate utilization not previously reported in isolation, such as formate and methanol metabolism in Mbac.
Abstract: The metabolism of archaeal methanogens drives methane release into the environment and is critical to understanding global carbon cycling. Methanogenesis operates at a very low reducing potential compared to other forms of respiration and is therefore critical to many anaerobic environments. Harnessing or altering methanogen metabolism has the potential to mitigate global warming and even be utilized for energy applications. Here, we report draft genome sequences for the isolated methanogens Methanobacterium bryantii, Methanosarcina spelaei, Methanosphaera cuniculi, and Methanocorpusculum parvum. These anaerobic, methane-producing archaea represent a diverse set of isolates, capable of methylotrophic, acetoclastic, and hydrogenotrophic methanogenesis. Assembly and analysis of the genomes allowed for simple and rapid reconstruction of metabolism in the four methanogens. Comparison of the distribution of Clusters of Orthologous Groups (COG) proteins to a sample of genomes from the RefSeq database revealed a trend towards energy conservation in genome composition of all methanogens sequenced. Further analysis of the predicted membrane proteins and transporters distinguished differing energy conservation methods utilized during methanogenesis, such as chemiosmotic coupling in Msar. spelaei and electron bifurcation linked to chemiosmotic coupling in Mbac. bryantii and Msph. cuniculi. Methanogens occupy a unique ecological niche, acting as the terminal electron acceptors in anaerobic environments, and their genomes display a significant shift towards energy conservation. The genome-enabled reconstructed metabolisms reported here have significance to diverse anaerobic communities and have led to proposed substrate utilization not previously reported in isolation, such as formate and methanol metabolism in Mbac. bryantii and CO2 metabolism in Msph. cuniculi. The newly proposed substrates establish an important foundation with which to decipher how methanogens behave in native communities, as CO2 and formate are common electron carriers in microbial communities.

37 citations

Journal ArticleDOI
TL;DR: This report is the first description of psychrotolerant as well as marine butyrate--and propionate-oxidizing syntrophic organisms.
Abstract: Two anaerobic, psychrotolerant, syntrophic strains were enriched from permanently cold, shallow anoxic marine sediments in Skan Bay, Alaska. One strain, AK-B(T), oxidized butyrate syntrophically and was isolated in defined coculture with a H(2)-using methanogen or in a dixenic coculture that also contained an acetate-scavenging methanogen. The other enrichment culture syntrophically oxidized propionate. The growth of these syntrophic cultures was very slow: approximately 1 year for cocultures of strain AK-B(T) to form colonies and >1 year for the propionate-oxidizing enrichment to form colonies. Neither culture grew axenically when supplied with the catabolic substrates crotonate, pyruvate, malate, or sulfate plus butyrate or propionate. Strain AK-B(T) catabolized iso-butyrate in syntrophic coculture but did not catabolize valerate or caproate. Phylogenetic analyses of the 16S rRNA gene sequence suggested that strain AK-B(T) was only distantly related to cultivated sulfate-reducing bacteria, and that this strain represented a new genus. We propose Algorimarina butyrica, with strain AK-B(T) (=OCM 842(T)), as the type strain. This report is the first description of psychrotolerant as well as marine butyrate--and propionate-oxidizing syntrophic organisms.

37 citations

Journal ArticleDOI
TL;DR: Syntrophic acetogenic microorganisms were absent in the acidogenic reactor but present in the downstream methanogenic reactor, indicating the retention of various metabolic pathways also found in a single-stage system, and the determination of key microorganisms further expands the understanding of the complex biological functions in AD process.
Abstract: 2-Phase anaerobic digestion (AD), where the acidogenic phase was operated at 2day hydraulic retention time (HRT) and the methanogenic phase at 10days HRT, had been evaluated to determine if it could provide higher organic reduction and methane production than the conventional single-stage AD (also operated at 12days HRT). 454 pyrosequencing was performed to determine and compare the microbial communities. The acidogenic reactor of the 2-phase system yielded a unique bacterial community of the lowest richness and diversity, while bacterial profiles of the methanogenic reactor closely followed the single-stage reactor. All reactors were predominated by hydrogenotrophic methanogens, mainly Methanolinea. Unusually, the acidogenic reactor contributed up to 24% of total methane production in the 2-phase system. This could be explained by the presence of Methanosarcina and Methanobrevibacter, and their activities could also help regulate reactor alkalinity during high loading conditions through carbon dioxide production. The enrichment of hydrolytic and acidogenic Porphyromonadaceae, Prevotellaceae, Ruminococcaceae and unclassified Bacteroidetes in the acidogenic reactor would have contributed to the improved sludge volatile solids degradation, and ultimately the overall 2-phase system's performance. Syntrophic acetogenic microorganisms were absent in the acidogenic reactor but present in the downstream methanogenic reactor, indicating the retention of various metabolic pathways also found in a single-stage system. The determination of key microorganisms further expands our understanding of the complex biological functions in AD process.

37 citations

Journal ArticleDOI
TL;DR: Using experimental approaches based on DNA sequences identifying either methanogen‐specific or methanotroph‐specific gene sequences methods were developed to broaden the detection and identification of methane metabolizing bacteria in natural environments, focused on blanket bog peat.
Abstract: The role of methane as a greenhouse gas and the contribution of bacteria to the production (methanogenesis) and destruction (methane oxidation) of methane is described. Using experimental approaches based on DNA sequences identifying either methanogen-specific or methanotroph-specific gene sequences methods were developed to broaden the detection and identification of methane metabolizing bacteria in natural environments. These methods were focused on blanket bog peat but are suitable for other environments. In addition to group specific 16S rRNA DNA sequences, specific functional gene probes based on methane coenzyme reductase sequences for methanogens and methane monooxygenase sequences for methanotrophs, were developed. These sequences were used in PCR-based protocols to detect and amplify specific gene sequences from the total DNA isolated from transverse sections of blanket bog peat. This permitted the analysis of the vertical distribution of methanogen and methanotroph populations, discrimination between different sub-sets of these populations, and the identification of novel organisms not previously detected by culture-based methods.

37 citations


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