Methane methanotrophic bacteria

Strong evidence that the methanotrophic bacteria use the Wood-Ljungdahl pathway in reverse for the conversion of acetate to methane. ... 

In some cases, microorganisms can transform a contaminant, but they are not able to use this compound as a source of energy or carbon. This biotransformation is often called co-metabolism. In co-metabolism, the transformation of the compound is an incidental reaction catalyzed by enzymes, which are involved in the normal microbial metabolism.33 A well-known example of co-metabolism is the degradation of (TCE) by methanotrophic bacteria, a group of bacteria that use methane as their source of carbon and energy. When metabolizing methane, methanotrophs produce the enzyme methane monooxygenase, which catalyzes the oxidation of TCE and other chlorinated aliphatics under aerobic conditions.34 In addition to methane, toluene and phenol have been used as primary substrates to stimulate the aerobic co-metabolism of chlorinated solvents. 

Copper enzymes are involved in reactions with a large number of other, mostly inorganic substrates. In addition to its role in oxygen and superoxide activation described above, copper is also involved in enzymes that activate methane, nitrite and nitrous oxide. The structure of particulate methane mono-oxygenase from the methanotrophic bacteria Methylococcus capsulatus has been determined at a resolution of 2.8 A. It is a trimer with an a3P33 polypeptide arrangement. Two metal centres, modelled as mononuclear and dinuclear copper, are located in the soluble part of each P-subunit, which resembles CcOx subunit II. A third metal centre, occupied by Zn in the crystal, is located within the membrane. 

Oremland et al. [136] subsequently demonstrated that methane-oxidizing bacteria also had the capacity to co-oxidize methyl bromide by methane monooxygenase produced during the oxidation of methane to methanol. They also showed that methanotrophic soils that had a high capacity to oxidize methane degraded14C-labeled methyl bromide to 14C02. 

The Biotrol methanotrophic bioreactor system is an ex situ remedial technology that uses methanotrophic bacteria to degrade contaminants in groundwater. Methanotrophs use methane... 

The U.S. Department of Energy s Office of Technology Development has sponsored full-scale environmental restoration technology demonstrations since 1990. The Savannah River Site Integrated Demonstration focuses on the bioremediation of groundwater contaminated by chlorinated solvents. Several laboratories, including the Savannah River site, have demonstrated the ability of methanotrophic bacteria (i.e., those that oxidize methane) found in soil, sediment, and aqueous material, to completely degrade or mineralize chlorinated solvents. 

Methane-oxidizing bacteria, or methanotrophs, can play a central role in reducing CH4 emissions from estuaries, by converting CH4 into bacterial biomass or CO2 (Topp and Hanson, 1991). It has been estimated that methanotrophic bacteria in freshwater... 

Some preparations of iron exchanged into zeolite H-MFI by vapor-phase FeCL are known to be active and selective catalysts for the reduction of NO, with hydrocarbons or ammonia in the presence of excess oxygen and water vapor (45,46). The active centers in Fe/MFI are assumed to be binuclear, oxygen-bridged iron complexes, as follows from H2-TPR, CO-TPR, and ESR data (45,47) and EXAFS and XANES results (48,49). These complexes are structurally similar to the binuclear iron centers in methane monooxygenase enzymes that are employed by methanotrophic bacteria in utilization of methane as their primary energy source (50). It is believed that molecular oxygen reacts with these centers to form peroxide as the initial step in this chemistry (50). 

Methanotrophic bacteria use methane as the sole source of carbon and energy employing MMO to catalyze the first step in the methane oxidation pathway leading ultimately to CO2. 

Methane is subject to aerobic oxidation by methanotrophic bacteria when it diffuses across an anoxic-oxic interface before escaping to the atmosphere (King, 1992) ... 

Methane oxidation can be limited by nitrogen due to enzyme-level inhibition or unmet metha-notroph nitrogen demand. The oxidation of CH4 by methanotrophic bacteria and by... 

Gilbert B. and Frenzel P. (1995) Methanotrophic bacteria in the rhizosphere of rice microcosms and their effect on porewater methane concentration and methane emission. Biol. Fertility... 

A metalimnion (the transitional layer between the epilimnion and the hypolim-nion) contains methanotrophic bacteria (bacteria that aerobically oxidize methane) at a cell concentration of 105 cells per milliliter. There is adequate oxygen available and the cells have a Vmax for CH4 of 10-19 mol/(cell sec) and a half saturation constant, Ks, of 10 4 mol/liter. At what rate, RCH<, is methane degraded if it is present at a concentration of 1.5 X 10-5 M ... 

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