Methanogen

About: Methanogen is a research topic. Over the lifetime, 1146 publications have been published within this topic receiving 48254 citations.

The complete genome sequence of the rumen methanogen Methanosarcina barkeri CM1.

Abstract: Methanosarcina species are the most metabolically versatile of the methanogenic Archaea and can obtain energy for growth by producing methane via the hydrogenotrophic, acetoclastic or methylotrophic pathways. Methanosarcina barkeri CM1 was isolated from the rumen of a New Zealand Friesian cow grazing a ryegrass/clover pasture, and its genome has been sequenced to provide information on the phylogenetic diversity of rumen methanogens with a view to developing technologies for methane mitigation. The 4.5 Mb chromosome has an average G + C content of 39 %, and encodes 3523 protein-coding genes, but has no plasmid or prophage sequences. The gene content is very similar to that of M. barkeri Fusaro which was isolated from freshwater sediment. CM1 has a full complement of genes for all three methanogenesis pathways, but its genome shows many differences from those of other sequenced rumen methanogens. Consequently strategies to mitigate ruminant methane need to include information on the different methanogens that occur in the rumen.

Effect of Bioaugmentation on Biogas Yields and Kinetics in Anaerobic Digestion of Sewage Sludge.

Abstract: Bioaugmentation with a mixture of microorganisms (Bacteria and Archaea) was applied to improve the anaerobic digestion of sewage sludge. The study was performed in reactors operating at a temperature of 35 °C in semi-flow mode. Three runs with different doses of bioaugmenting mixture were conducted. Bioaugmentation of sewage sludge improved fermentation and allowed satisfactory biogas/methane yields and a biodegradation efficiency of more than 46%, despite the decrease in hydraulic retention time (HRT) from 20 d to 16.7 d. Moreover, in terms of biogas production, the rate constant k increased from 0.071 h−1 to 0.087 h−1 as doses of the bioaugmenting mixture were increased, as compared to values of 0.066 h−1 and 0.069 h−1 obtained with sewage sludge alone. Next-generation sequencing revealed that Cytophaga sp. predominated among Bacteria in digesters and that the hydrogenotrophic methanogen Methanoculleus sp. was the most abundant genus among Archaea.

Introduction to microbial and thermal methane

Abstract: Commercially, important accumulations of natural gas contain methane formed by two distinctly different processes. Microbial methane, produced biologically by methanogens, makes up roughly 20 percent of all known commercial gas accumulations, whereas thermal methane, generated during the thermochemical alteration of organic matter, accounts for the remaining 80 percent. Microbial and thermal methane can often be distinguished by isotopic and molecular ratios such as [delta][sup 13]C, [delta]D, and methane/(ethane+propane) [C[sub 1]/(C[sub 2]+C[sub 3])]. Microbial methane is produced in strictly anaerobic environments such as numerous aquatic environments, both marine and freshwater. Methanogens exist at surprising depths in the Earth's crust, at temperatures as high as 97[degrees]C. The primary metabolic processes by which methanogens gain energy are fermentation of acetate (CH[sub 3]COO-) and reduction of CO[sub 2]. Other processes can occur depending upon the species of methanogen and the type of available organic matter (such as conversion of formate, methanol, methylamines, and methylated reduced sulfur compounds to methane), but in most cases these processes are not significant ones in nature. CO[sub 2] reduction dominates in marine sediments, whereas acetate fermentation is most common in freshwater sediments. Thermal or thermogenic methane is formed as organic-rich sediments move through progressively higher thermal maturity regimes foundmore » during increasing depths of burial. Thermal methane results from the thermochemical decomposition of organic matter. During early thermal maturation, thermal methane is accompanied by other hydrocarbon and non-hydrocarbon gases and is often associated with crude oil. At the highest thermal maturities, methane alone is formed by cracking of carbon-carbon bonds in kerogen, bitumen, and oils. 18 refs., 5 figs., 2 tabs.« less

Is methane a new therapeutic gas

Abstract: Background: Methane is an attractive fuel. Biologically, methanogens in the colon can use carbon dioxide and hydrogen to produce methane as a by-product. It was previously considered that methane is not utilized by humans. However, in a recent study, results demonstrated that methane could exert anti-inflammatory effects in a dog small intestinal ischemia-reperfusion model. Point of view: Actually, the bioactivity of methane has been investigated in gastrointestinal diseases, but the exact mechanism underlying the anti-inflammatory effects is required to be further elucidated. Methane can cross the membrane and is easy to collect due to its abundance in natural gas. Although methane is flammable, saline rich in methane can be prepared for clinical use. These seem to be good news in application of methane as a therapeutic gas. Conclusion: Several problems should be resolved before its wide application in clinical practice.