Methanotrophes

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

Alvarez-Cohen L, McCarty PL. 1991a. Effects of toxicity, aeration and reductant supply on trichloroethylene transformation by a mixed methanotrophic culture. Appl Environ Microbiol 57 228-235. 

Alvarez-Cohen L, McCarty PL. 1991b. Product toxicity and cometabolic competitive inhibition modeling of chloroform and trichloroethylene transformation by methanotrophic resting cells. Appl Environ Microbiol 57 1031-1037. 

Bowman JP, Jimenez L, Rosario 1, et al. 1993. Characterization of the methanotrophic bacterial community present in a trichloroethylene-contaminated subsurface groundwater site. Appl Environ Microbiol 59 2380-2387. 

Henry SM, Grbic-Galic D. 1991a. Influence of endogenous and exogenous electron donors and trichloroethylene oxidation toxicity on trichloroethylene oxidation by methanotrophic cultures from a groundwater aquifer. Appl Environ Microbiol 57 236-244. 

A few of the reactions carried out by the monooxygenase system of methanotrophic bacteria are summarized in Figure 2.9, and it is on account of this that methylotrophs have received attention for their technological potential (Lidstrom and Stirling 1990). An equally wide metabolic potential has also been demonstrated for cyclohexane monooxygenase, which has been shown to accomplish two broad types of reaction one in which formally nucleophilic oxygen reacts with the substrate, and... 

FIGURE 2.9 Reactions mediated by the monooxygenase system of methanotrophic bacteria. 

Dedysh SN, C Knief, PF Dunfield (2005) Methylocella species are facultatively methanotrophic. J Bacterial 187 4665-4670. 

The acetyl-coenzyme A decarbonylase synthase complex contains five polypeptide sub-nnits and in acetate-degrading methanotrophs, such as Methanosarcina barkeri and M. thermophila, catalyzes the formation of methane and COj from acetyl-CoA ... 

Methane monooxygenase may exist in either soluble (sMMO) or particulate (pMMO) forms. These display different substrate ranges and different rates of transformation rates, and most methanotrophs express only the latter form of the enzyme (Hanson and Hanson 1996). The particulate form of methane monooxygenase contains copper, or both copper... 

Fox BG, Wa Froland, JE Dege, JD Lipscomb (1989) Methane monooxygenase from Methylosinus trichospo-rium OB3b. Purification and properties of a three-component system with a high specific activity from a type II methanotroph. J Biol Chem 264 10023-10033. 

FIGURE 7.65 Generalized degradation of trihaloethenes by methanotrophs. (FromNeilson, A.H. and Allard, A.-S., The Handbook of Environmental Chemistry, Vol. 3R, pp. 1-74, Springer, 2002. With permission.)... 

Newman LM, LP Wackett (1991) Fate of 2,2,2-trichloroacetaldehyde (chloral hydrate) produced during trichloroethylene oxidation by methanotrophs. Appl Environ Microbiol 57 2399-2402. 

Flnoromethane has been nsed as a selective inhibitor of ammoninm oxidation and nitrification-linked synthesis of N2O in Nitrosomonas europaea (Miller et al.l993), while difluoromethane has been proposed as a reversible inhibitor of methanotrophs (Miller et al. 1998). 

The methanotroph Methylosinus trichosporium strain OB3b that produces the soluble MMO system consisting of a 40 kDa NADH oxidoreductase, a 245 kDa hydroxylase, and a 16 kDa protein termed component B has a low substrate specificity (Sullivan et al. 1998). 

DeElaun ME, BD Ensley, RJ Steffan (1992) Biological oxidation of hydrochlorofluorocarbons (HCECs) by a methanotrophic bacterium. Biotechnology 10 1576-1578. 

Sullivan JP, D Dickinson, HA Chase (1998) Methanotrophs, Methylosinus trichosporium OB3b, sMMO, and their application to bioremediation. Crit Rev Microbiol 24 335-373. 

Adriaens P (1994) Evidence for chlorine migration during oxidation of 2-chlorobiphenyl by a type 11 methanotroph. Appl Environ Microbiol 60 1658-1662. 

A rearrangement (NIH shift) occurred during the transformation of 2-chlorobiphenyl to 2-hydroxy-3-chlorobiphenyl by a methanotroph, and is consistent with the formation of an intermediate arene oxide (Adriaens 1994). The occurrence of such intermediates also offers plausible mechanisms for the formation of nitro-containing metabolites that have been observed in the degradation of 4-chlo-robiphenyl in the presence of nitrate (Sylvestre et al. 1982). 

King GM (1994) Association of methanotrophs with the roots and rhizomes of aquatic vegetation. Appl Environ Microbiol 60 3220-3227. 

Isotope ratios for and Cl were measured for the aerobic degradation of dichlorometh-ane by a methanotroph MC8b (Heraty et al. 1999). Values of the fractionation factor (a) were 0.9586 for carbon and 0.9962 for chlorine, and kinetic isotope effects were 1.0424 for carbon and 1.0038 for chlorine. 

TCE is not able to support the growth of a single organism, but it is susceptible to cooxidation by oxygenases elaborated by organisms dnring growth with structurally unrelated substrates. A review of methanotrophic bacteria (Hanson and Hanson 1996) contains a useful account of their application to bioremediation of TCE-contaminated sites. 

T. Vallaeys, E. Topp, G. Muyzer, V. Macheret, G. Laguerre, A. Rigaud, and G. Soulas, Evaluation of denaturing gradient gel electrophoresis in the detection of I6S rDNA sequence variation in rhizobia and methanotrophs. FEMS Microbiol. Ecol. 24 279 (1997). 

Methanotrophs rely on the enzymatic system methane monooxygenase (MMO) to catalyze the first step in the metabolism of methane, shown in Eq. (1) (1, 14). 

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