Incorporation of Oxygen from Water into Toluene and Benzene during Anaerobic Fermentative Transformation

Vogel, Timothy M.; Grbić-Galić, D.

doi:10.1128/aem.52.1.200-202.1986

Cited by 220 publications

(108 citation statements)

References 8 publications

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“…Other compounds sought (based on presumed degradation pathways) but not detected included benzaldehyde, 2-, 3-and 4-methylcyclohexanol, catechol (1, 2-dihydroxybenzene), methylcatechol, resorcinol (1, 3-dihydroxybenzene), methylresorcinol, 2-, 3-and 4-hydroxybenzoate, 2-, 3and 4-hydroxybenzylalcohol, and gentisate. Although hydroxylated intermediates have been previously identified during methanogenic toluene degradation (Vogel and Grbic'-Galic', 1986), they may also be produced during aerobic biodegradation (Gibson and Subra-manian, 1984). Recent reports showed that hydroxylated compounds may be formed abiotically during sample processing (Kunapuli et al, 2008).…”

Section: Compounds Detected During Methanogenic Toluene Metabolismmentioning

confidence: 99%

“…Earlier investigations examining toluene biodegradation under methanogenic conditions have also implicated metabolites such as o-cresol, o-methylcyclohexanol, p-cresol, p-methylcyclohexanol, methylcyclohexane, 2-hydroxybenzoate, benzylalcohol, benzaldehyde and benzoate (Grbic'-Galic' and Vogel, 1987), suggesting that alternative mechanisms of toluene activation in the absence of endogenous electron acceptors, such as ring or methyl group hydroxylation, may be possible. In studies using 18 O-H2O, Vogel and Grbic'-Galic' (1986) showed the incorporation of an 18 O atom into toluene forming labelled p-cresol, demonstrating that hydroxylation may also occur under methanogenic conditions.…”

Section: Introductionmentioning

confidence: 99%

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Methanogenic toluene metabolism: community structure and intermediates

Fowler

Dong²,

Sensen³

et al. 2011

Environmental Microbiology

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Toluene is a model compound used to study the anaerobic biotransformation of aromatic hydrocarbons. Reports indicate that toluene is transformed via fumarate addition to form benzylsuccinate or by unknown mechanisms to form hydroxylated intermediates under methanogenic conditions. We investigated the mechanism(s) of syntrophic toluene metabolism by a newly described methanogenic enrichment from a gas condensate-contaminated aquifer. Pyrosequencing of 16S rDNA revealed that the culture was comprised mainly of Clostridiales. The predominant methanogens affiliated with the Methanomicrobiales. Methane production from toluene ranged from 72% to 79% of that stoichiometrically predicted. Isotope studies using (13)C(7) toluene showed that benzylsuccinate and benzoate transiently accumulated revealing that members of this consortium can catalyse fumarate addition and subsequent reactions. Detection of a BssA gene fragment in this culture further supported fumarate addition as a mechanism of toluene activation. Transient formation of cresols, benzylalcohol, hydroquinone and methylhydroquinone suggested alternative mechanism(s) for toluene metabolism. However, incubations of the consortium with (18)O-H(2)O showed that the hydroxyl group in these metabolites did not originate from water and abiotic control experiments revealed abiotic formation of hydroxylated species due to reactions of toluene with sulfide and oxygen. Our results suggest that toluene is activated by fumarate addition, presumably by the dominant Clostridiales.

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Section: Compounds Detected During Methanogenic Toluene Metabolismmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Methanogenic toluene metabolism: community structure and intermediates

Fowler

Dong²,

Sensen³

et al. 2011

Environmental Microbiology

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“…Methyl substituents of the aromatic ring are difficult to attack in the absence of molecular oxygen, which normally initiates degradation. Methylated aromatic compounds, that are readily degraded anaerobically include toluene (Vogel and Grbic-Galic, 1986;Wilson et al, 1986;Zeyer et al, 1986;Dolfing et al, 1990: Lovley andLonergan, 1990;Schocher et al, 1991 ;Rabus et al, 1993;Fries et al, 1994: Rueter et al, 1994 and the ortho, rnetu and para isomers of xylene (Zeyer et al, 1986;Evans et al, 1991Evans et al, , 1992Seyfried et al, 1994;Edwards and Grbic-Galic, 1994;Rueter et al, 1994;Haner et al, 1995) and of cresol (Lovley and Lonergan, 1990;Hopper et al, 1991 ;Rudolphi et al, 1991 ;Flyvbjerg et al, 1993;Bonting et al, 1995). At least two different pathways can be used for the first attack under anaerobic conditions.…”

Section: Reductive Dehalogenationmentioning

confidence: 99%

Anaerobic Metabolism of Aromatic Compounds

Heider

Fuchs

1997

European Journal of Biochemistry

285

217

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Aromatic compounds comprise a wide variety of low-molecular-mass natural compounds (amino acids, quinones, flavonoids, etc.) and biopolymers (lignin, melanin). They are almost exclusively degraded by microorganisms. Aerobic aromatic metabolism is characterised by the extensive use of molecular oxygen. Monoxygenases and dioxygenases are essential for the hydroxylation and cleavage of aromatic ring structures. Accordingly, the characteristic central intermediates of the aerobic pathways (e.g. catechol) are readily attacked oxidatively. Anaerobic aromatic catabolism requires, of necessity, a quite different strategy. The basic features of this metabolism have emerged from studies on bacteria that degrade soluble aromatic substrates to CO, in the complete absence of molecular oxygen.Essential to anaerobic aromatic metabolism is the replacement of all the oxygen-dependent steps by an alternative set of novel reactions and the formation of different central intermediates (e.g. benzoylCoA) for breaking the aromaticity and cleaving the ring; notably, in anaerobic pathways, the aromatic ring is reduced rather than oxidised. The two-electron reduction of benzoyl-CoA to a cyclic diene requires the cleavage of two molecules of ATP to ADP and P, and is catalysed by benzoyl-CoA reductase. After nitrogenase, this is the second enzyme known which overcomes the high activation energy required for reduction of a chemically stable bond by coupling electron transfer to the hydrolysis of ATP. The alicyclic product cyclohex-I ,5-diene-l-carboxyl-CoA is oxidised to acetyl-CoA via a modified P-oxidation pathway ; the ring structure is opened hydrolytically. Some phenolic compounds are anaerobically transformed to resorcinol (1,3-dihydroxybenzene) or phloroglucinol (1,3,5-trihydroxybenzene). These intermediates are also first reduced and then as alicyclic products oxidised to acetyl-CoA.This review gives an outline of the anaerobic pathways which allow bacteria to utilize aromatics even in the absence of oxygen. We focus on previously unknown reactions and on the enzymes characteristic for such novel metabolism.Keywords ; aromatic metabolism ; benzoyl-CoA ; anaerobic bacteria ; aromatic-ring reduction ; phloroglucinol; resorcinol.This review deals with the art of degrading aromatic compounds to CO, in the complete absence of molecular oxygen. This ability allows bacteria to make use of natural compounds of this widespread class as substrates for growth under anoxic conditions. In nature, anoxic conditions are created when oxygen consumption exceeds its supply. This situation prevails in many environments, e.g. in the intestinal tract of animals and man, in the sediments of all natural bodies of water, in ground water and in part in soil. Aromatic compounds are produced or transformed by all organisms, plants being the most prolific producers. There are numerous low-molecular-mass aromatic compounds includ-

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“…Anaerobic benzene degradation has been described in several publications with nitrate, sulfate and ferric iron as electron acceptors in microcosms and enrichments (Vogel and Grbic-Galic, 1986;Edwards and Grbic-Galic, 1992;Lovley et al, 1994;Phelps et al, 1996;Kazumi et al, 1997;Burland and Edwards, 1999;Lovley, 2000;Zwolinski et al, 2000;Jahn et al, 2005;Kunapuli et al, 2007). Even methanogenic cultures are known (Vogel and Grbic-Galic, 1986;Ulrich et al, 2005) and two denitrifying pure cultures degrading benzene have been described (Coates et al, 2001a;Kasai et al, 2006). However, there is still no definitive study on the nature of the activation mechanism.…”

Section: Introductionmentioning

confidence: 99%

Identification of intermediates formed during anaerobic benzene degradation by an iron‐reducing enrichment culture

Kunapuli

Griebler

Beller

et al. 2008

Environmental Microbiology

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Anaerobic benzene degradation is an important process in contaminated aquifers but is poorly understood due to the scarcity of microbial cultures for study. We have enriched a ferric iron-reducing culture that completely mineralizes benzene to CO(2). With (13)C(6)-labelled benzene as the growth substrate, ring-labelled benzoate was identified as a major intermediate by liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis of culture supernatants. With increasing incubation time, (13)C(7)-labelled benzoate appeared, indicating that the carboxyl group of benzoate derived from CO(2) that was produced from mineralization of labelled benzene. This was confirmed by growing the culture in (13)C-bicarbonate-buffered medium with unlabelled benzene as the substrate, as the label appeared in the carboxyl group of benzoate produced. Phenol was also identified as an intermediate at high concentration. However, it was clearly shown that phenol was formed abiotically by autoxidation of benzene during the sampling and analysis procedure as a result of exposure to air. The results suggest that, in our culture, anaerobic benzene degradation proceeds via carboxylation and that caution should be exercised in interpreting hydroxylated benzene derivatives as metabolic intermediates of anaerobic benzene degradation.

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Incorporation of Oxygen from Water into Toluene and Benzene during Anaerobic Fermentative Transformation

Cited by 220 publications

References 8 publications

Methanogenic toluene metabolism: community structure and intermediates

Methanogenic toluene metabolism: community structure and intermediates

Anaerobic Metabolism of Aromatic Compounds

Identification of intermediates formed during anaerobic benzene degradation by an iron‐reducing enrichment culture

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