Dichloromethane and trichloroethylene inhibition of methane oxidation by the membrane-associated methane monooxygenase of Methylosinus trichosporium OB3b

Lontoh, Sonny; DiSpirito, Alan A.; Semrau, Jeremy D.

doi:10.1007/s002030050714

Cited by 30 publications

(20 citation statements)

References 33 publications

(37 reference statements)

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“…Cells expressing sMMO were grown and harvested as described earlier. To further verify that sMMO was responsible for oxidation of biphenyl, cells expressing sMMO were inactivated with acetylene as described earlier (Lontoh et al 1999) and oxygen uptake was measured in the presence of 125 µM biphenyl. As a second control, M. trichosporium OB3b expressing pMMO was also added to the oxygen-uptake reactor at a concentration of 0.2 g (wet wt) ml -1 and incubated with 125 µM biphenyl.…”

Section: Methodsmentioning

confidence: 99%

Transformation of ortho -substituted biphenyls by Methylosinus trichosporium OB3b: substituent effects on oxidation kinetics and product formation

Lindner

Adriaens

Semrau

2000

Archives of Microbiology

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The ability of Methylosinus trichosporium OB3b, expressing soluble methane monooxygenase, to oxidize a range of ortho-substituted biphenyls was examined to better understand how substituents affect both the rate and products of oxidation in comparison to biphenyl. Inhibition of oxidation was observed over the tested substrate range for both biphenyl and ortho-halogenated biphenyls (2-chloro-, 2-bromo-, and 2-iodobiphenyl). No inhibition was observed during the oxidation of 2-hydroxybiphenyl and 2-methylbiphenyl. Analysis of the products of oxidation showed that, depending on the substituent, ring hydroxylation, substituent oxidation, and elimination pathways could occur. The type and abundance of products formed along with the relatively high kinetic isotope effect observed for deuterated vs. nondeuterated biphenyl (k(h)/k(d) = 3.4+/-0.02) are consistent with mechanisms that include both hydrogen abstraction and NIH-shift pathways. Knowledge of these substituent-dependent reaction rates and mechanisms enhances our understanding of the methanotrophic aryl transformation potential and allows for better prediction of the formation of oxidized intermediates by methanotrophic bacteria.

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Section: Methodsmentioning

confidence: 99%

Transformation of ortho -substituted biphenyls by Methylosinus trichosporium OB3b: substituent effects on oxidation kinetics and product formation

Lindner

Adriaens

Semrau

2000

Archives of Microbiology

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“…Phenylacetylene (PA) is a differential inhibitor of the soluble and particulate forms of the enzyme at relatively low concentrations (Stirling and Dalton, 1979;Prior and Dalton, 1985;Lontoh et al, 1999;Lontoh et al, 2000a). At a low concentration (100 μM), PA causes almost no inhibition of pMMO, but causes greater than 90% inhibition of the sMMO (Lontoh et al, 2000a).…”

Section: Coumarin Oxidation Assaymentioning

confidence: 99%

“…Cells that are cometabolizing TCE often require a reductant, as the cometabolic reaction is often reductant limited. Formate, a readily reducible substrate and electron donor, has been shown to enhance the rates of both methane and TCE oxidation and, as such, should increase sMMO activity (Lontoh and Semrau, 1998;Lontoh et al, 1999;Alvaraz-Cohen and McCarty, 1991). This increase in sMMO activity should be reflected in an elevated fluorescence response with the coumarin assay, in the presence of formate.…”

mentioning

confidence: 99%

Field Evidence for Intrinsic Aerobic Chlorinated Ethene Cometabolism by Methanotrophs Expressing Soluble Methane Monooxygenase

Wymore¹,

Lee²,

Keener³

et al. 2007

Bioremediation Journal

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Idaho National Laboratory's Test Area North is the site of a trichloroethene (TCE) plume resulting from waste injections. Previous investigations revealed that TCE was being attenuated relative to two codisposed internal tracers, tritium and tetrachloroethene, with a half-life of 9 to 21 years. Biological attenuation mechanisms were investigated using a novel suite of assays, including enzyme activity probes designed for the soluble methane monooxygenase (sMMO) enzyme. Samples were analyzed for chlorinated solvents, tritium, redox parameters, primary substrates, degradation products, bacterial community methanotrophic potential, and bacterial DNA. The enzyme probe assays, methanotrophic enrichments and isolations, and DNA analysis documented the presence and activity of indigenous methanotrophs expressing the sMMO enzyme. Three-dimensional groundwater data showed plume-wide aerobic conditions, with low levels of methane and detections of carbon monoxide, a by-product of TCE cometabolism. The TCE half-life attributed to aerobic cometabolism is 13 years relative to tritium, based on the tracer-corrected method. Similarly, a half-life of 8 years was estimated for cisdichloroethene (DCE). Although these rates are slower than most anaerobic degradation processes, they can be significant for large plumes. This investigation is believed to be the first documentation of intrinsic aerobic TCE and DCE cometabolism in an aquifer by indigenous methanotrophs.

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“…As such, the use of methanotrophs for the in situ remediation of chlorinated ethenes is problematic due to the competition of both the pollutant(s) and the obligate growth substrate for binding to MMO (21,31,36). To further complicate matters, some methanotrophs can express two forms of MMO.…”

mentioning

confidence: 99%

“…Of those methanotrophs that have the genes encoding polypeptides of the sMMO, these genes are expressed only when the level of copper is very low (10,23). Furthermore, regardless of the form of MMO expressed, not only does competition exist between methane and chlorinated ethenes for binding, the product and substrate toxicity associated with these pollutants can and does occur (21,31,36,37).…”

mentioning

confidence: 99%

Mixed Pollutant Degradation by Methylosinus trichosporium OB3b Expressing either Soluble or Particulate Methane Monooxygenase: Can the Tortoise Beat the Hare?

Lee

Keeney

Lim

et al. 2006

Appl Environ Microbiol

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Methanotrophs have been widely investigated for in situ bioremediation due to their ubiquity and their ability to degrade halogenated hydrocarbons through the activity of methane monooxygenase (MMO). It has been speculated that cells expressing the soluble form of MMO (sMMO) are more efficient in cleaning up sites polluted with halogenated hydrocarbons due to its broader substrate range and relatively fast degradation rates compared cells expressing the other form of MMO, the particulate MMO (pMMO). To examine this issue, the biodegradation of mixtures of chlorinated solvents, i.e., trichloroethylene (TCE), trans-dichloroethylene (t-DCE), and vinyl chloride (VC), by Methylosinus trichosporium OB3b in the presence of methane using either form of MMO was investigated over longer time frames than those commonly used, i.e., days instead of hours. Growth of M. trichosporium OB3b along with pollutant degradation were monitored and analyzed using a simple comparative model developed from the ⍀ model created for analysis of the competitive binding of oxygen and carbon dioxide by ribulose bisphosphate carboxylase. From these findings, it appears that at concentrations of VC, t-DCE, and TCE greater than 10 M each, methanotrophs expressing pMMO have a competitive advantage over cells expressing sMMO due to higher growth rates. Despite such an apparent growth advantage, pMMO-expressing cells degraded less of these substrates at these concentrations than sMMO-expressing cells during active growth. If the concentrations were increased to 100 M, however, not only did pMMO-expressing cells grow faster, they degraded more of these pollutants and did so in a shorter amount of time. These findings suggest that the relative rates of growth substrate and pollutant degradation are important factors in determining which form of MMO should be considered for pollutant degradation.Chlorinated hydrocarbons are used for a variety of uses, including degreasing of metal parts, scouring of textiles, and the production of organic chemicals and pharmaceuticals. Due to their extensive uses coupled with both accidental and purposeful releases, these compounds are commonly found in subsurface soils and groundwater (38,45). Although these compounds are refractory, they have been shown to be degraded through a variety of microbially mediated processes. Specifically, under anaerobic conditions, many of these compounds have been shown to be reductively dechlorinated (6,15,25,33,34,42). Under aerobic conditions, some of these compounds can be utilized as growth substrates (12, 24) or more commonly cooxidized in conjunction with a growth substrate such as methane, ammonia, toluene, or phenol (3, 4, 17-21, 30, 32, 36, 37, 41, 43, 44). Of the cells capable of growth on these substrates, methanotrophs are often used for the degradation of chlorinated hydrocarbons due to their ubiquity (23).In methanotrophs, the enzyme responsible for chlorinated solvent degradation, methane monooxygenase (MMO), is also responsible for the initial oxidation of the sole gro...

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Dichloromethane and trichloroethylene inhibition of methane oxidation by the membrane-associated methane monooxygenase of Methylosinus trichosporium OB3b

Cited by 30 publications

References 33 publications

Transformation of ortho -substituted biphenyls by Methylosinus trichosporium OB3b: substituent effects on oxidation kinetics and product formation

Transformation of ortho -substituted biphenyls by Methylosinus trichosporium OB3b: substituent effects on oxidation kinetics and product formation

Field Evidence for Intrinsic Aerobic Chlorinated Ethene Cometabolism by Methanotrophs Expressing Soluble Methane Monooxygenase

Mixed Pollutant Degradation by Methylosinus trichosporium OB3b Expressing either Soluble or Particulate Methane Monooxygenase: Can the Tortoise Beat the Hare?

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