The Experts below are selected from a list of 15 Experts worldwide ranked by ideXlab platform
J. Colin Murrell - One of the best experts on this subject based on the ideXlab platform.
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Community‐Level Analysis: Key Genes of Aerobic Methane Oxidation
Methods in Enzymology, 2020Co-Authors: Marc G. Dumont, J. Colin MurrellAbstract:Abstract Aerobic Methane‐oxidizing bacteria (methanotrophs) are a diverse group of bacteria that are currently represented by 13 recognized genera. They play a major role in the global Methane cycle and are widespread in nature with representatives found in soils, freshwater, seawater, freshwater and marine sediments, peat bogs and at extremes of temperature, salinity, and pH. There has been an interest in methanotrophs for their potential in bioremediation processes. Methanotroph diversity and ecology are often studied using the “functional” genes pmoA, mmoX, and mxaF, encoding subunits of the particulate Methane Monooxygenase, Soluble Methane Monooxygenase, and the methanol dehydrogenase, respectively. This chapter describes methods used to detect and analyze these functional genes.
Marc G. Dumont - One of the best experts on this subject based on the ideXlab platform.
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Community‐Level Analysis: Key Genes of Aerobic Methane Oxidation
Methods in Enzymology, 2020Co-Authors: Marc G. Dumont, J. Colin MurrellAbstract:Abstract Aerobic Methane‐oxidizing bacteria (methanotrophs) are a diverse group of bacteria that are currently represented by 13 recognized genera. They play a major role in the global Methane cycle and are widespread in nature with representatives found in soils, freshwater, seawater, freshwater and marine sediments, peat bogs and at extremes of temperature, salinity, and pH. There has been an interest in methanotrophs for their potential in bioremediation processes. Methanotroph diversity and ecology are often studied using the “functional” genes pmoA, mmoX, and mxaF, encoding subunits of the particulate Methane Monooxygenase, Soluble Methane Monooxygenase, and the methanol dehydrogenase, respectively. This chapter describes methods used to detect and analyze these functional genes.
Donghyun Park - One of the best experts on this subject based on the ideXlab platform.
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Biological conversion of Methane to methanol
Korean Journal of Chemical Engineering, 2013Co-Authors: Donghyun ParkAbstract:The conversion of Methane to methanol is important to economic utilization of natural/shale gas. Methanol is a valuable liquid fuel and raw material for various synthetic hydrocarbon products. Its industrial production is currently based on a two-step process that is energy-intensive and environmentally unfriendly, requiring high pressure and temperature. The biological oxidation of Methane to methanol, based on Methane Monooxygenase activity of methanotrophic bacteria, is desirable because the oxidation is highly selective under mild conditions, but conversion rate and yield and stability of catalytic activity should be improved up to an industrially viable level. Since methanotrophic bacteria produce methanol as only a precursor of formaldehyde that is then used to synthesize various essential metabolites, the direct use of bacteria seems unsuitable for selective production of a large amount of methanol. There are two types of Methane Monooxygenase: Soluble (sMMO) and particulate (pMMO) enzyme. sMMO consisting of three components (reductase, hydroxylase, and regulatory protein) features an ( αβγ )_2 dimer architecture with a di-iron active site in hydroxlase. pMMO, a trimer (pmoA, pmoB, and pmoC) in an α _3 β _3 γ _3 polypeptide arrangement is a copper enzyme with a di-copper active site located in the Soluble domain of pmoB subunit. Since the membrane transports electrons well and delivers effectively Methane with increased solubility in the lipid bilayer, pMMO seems more rationally designed enzyme in nature than sMMO. The engineering/evolution/modification of MMO enzymes using various biological and chemical techniques could lead to an optimal way to reach the ultimate goal of technically and economically feasible and environmentally friendly oxidation of Methane. For this, multidisciplinary efforts from chemical engineering, protein engineering, and bioprocess research sectors should be systematically combined.
Tong Chuan - One of the best experts on this subject based on the ideXlab platform.
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Molecular detection of diversity of methanogens and methanotrophs in natural wetland soil
Acta Ecologica Sinica, 2020Co-Authors: Tong ChuanAbstract:Methane is one of the most important greenhouse gases and plays an essential role in atmospheric chemistry.The largest single source of Methane is natural wetlands,which have been suggested to contribute significantly to the interannual variability of global Methane emissions.Methanogens and methanotrophs are the main functional microbial groups mediating Methane cycles of natural wetlands.Biogenic Methane is produced by methanogenic archaea or methanogens as the final step in anaerobic degradation of organic matter.However,only about half of the produced Methane is emitted to the atmosphere,while the remainder is oxidized by a diverse group of bacteria referred to as Methane oxidizing bacteria(MOB) or methanotrophs.It is evident that the studies on the diversity of methanogens and methanotrophs can assist with revealing microbial-mediated Methane cycles and the temporal-spatial heterogeneity of Methane emission from natural wetlands.Traditional methods based on laboratory culture techniques have been proven inadequate to describe the vast microbial diversity,because those methods miss more than 99% of the organisms while enriching those thriving in cultures but not numerically or functionally important in the environment.Introduction of molecular methods independent of culture techniques has vastly improved the potential to describe microbial diversity.The 16S ribosomal RNA(rRNA) gene is by far the most frequently used phylogenetic marker for studying microbial ecology and diversity in the environment.An additional approach includes the sequencing of functional genes that are unique to the physiology of the group of microorganisms studied.Methanogen and methanotroph communities have been characterized by employing the 16S rRNA gene or functional genes as molecular markers in different types of natural wetlands.The functional gene of methanogens is mcrA,which encodes subunits of Methyl-coenzyme M reductase;whilst the functional genes of methanotrophs include pmoA,mmoX and mxaF,which encode subunits of particulate Methane Monooxygenase,Soluble Methane Monooxygenase,and methanol dehydrogenase,respectively.Sequence-based mcrA or pmoA phylogeny is consistent with the 16S rRNA-based phylogeny.Thus,the mcrA or pmoA gene is a favorable functional gene and widely used to detect methanogens and methanotrophs in soils of natural wetlands.Studies to date have differentiated communities by analysis of clone libraries or by community fingerprinting by denaturing gradient gel electrophoresis(DGGE),temperature gradient gel electrophoresis(TGGE),or by terminal restriction fragment length polymorphism(T-RFLP) relying on differences in restriction fragment lengths between taxa.Additionally,fluorencence in situ hybridization(FISH) and real-time quantitative PCR(real-time qPCR) have also been applied for quantification of natural wetland-inhabiting methanogens and methanotrophs.Members of orders Methanosarcinales,Methanomicrobiales,Methanobacteriales,and of Rice cluster I have frequently been detected in natural wetlands.Methanogen communities generally change with the depth of soils in natural wetlands.Shifts related to vegetation,pH and temperature have also been reported.There are studies revealing the presence of both type Ⅰ and type Ⅱ methanotrophs in natural wetlands.Type Ⅰ methanotrophs generally dominate in nutrient-rich environments,whereas type Ⅱ methanotrophs generally dominate in nutrient-poor environments.This paper reviews the molecular biological tools used for detecting the diversity of methanogens and methanotrophs in soils of natural wetlands,such as T-RFLP,DGGE,FISH and real-time qPCR.Furthermore,two types of important marker genes in molecular detection are examined and the latest achievements in studies of the diversity of methanogens and methanotrophs in different types of natural wetlands are summarized.Based on review of literature,further studies on diversity of methanogens and methanotrophs in natural wetlands in China are suggested.
Alan A. Dispirito - One of the best experts on this subject based on the ideXlab platform.
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Membrane-Associated Quinoprotein Formaldehyde Dehydrogenase from Methylococcus capsulatus Bath
Journal of Bacteriology, 2001Co-Authors: James A. Zahn, David J. Bergmann, Jeffery M. Boyd, Ryan C. Kunz, Alan A. DispiritoAbstract:A membrane-associated, dye-linked formaldehyde dehydrogenase (DL-FalDH) was isolated from the obligate methylotroph Methylococcus capsulatus Bath. The enzyme was the major formaldehyde-oxidizing enzyme in cells cultured in high (above 1 μmol of Cu per mg of cell protein) copper medium and expressing the membrane-associated Methane Monooxygenase. Soluble NAD(P)+-linked formaldehyde oxidation was the major activity in cells cultured in low-copper medium and expressing the Soluble Methane Monooxygenase (Tate and Dalton, Microbiology 145:159–167, 1999; Vorholt et al., J. Bacteriol. 180:5351–5356, 1998). The membrane-associated enzyme is a homotetramer with a subunit molecular mass of 49,500 Da. UV-visible absorption, electron paramagnetic resonance, and electrospray mass spectrometry suggest the redox cofactor of the DL-FalDH is pyrroloquinoline quinone (PQQ), with a PQQ-to-subunit stochiometry of approximately 1:1. The enzyme was specific for formaldehyde, oxidizing formaldehyde to formate, and utilized the cytochrome b559/569 complex as the physiological electron acceptor.