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Marozava S, Merl-Pham J, Müller H, Meckenstock RU. Adaptation of Carbon Source Utilization Patterns of Geobacter metallireducens During Sessile Growth. Front Microbiol 2020; 11:1271. [PMID: 32655526 PMCID: PMC7324539 DOI: 10.3389/fmicb.2020.01271] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 05/19/2020] [Indexed: 11/13/2022] Open
Abstract
There are two main strategies known how microorganisms regulate substrate utilization: specialization on one preferred substrate at high concentrations in batch cultures or simultaneous utilization of many substrates at low concentrations in chemostats. However, it remains unclear how microorganisms utilize substrates at low concentrations in the subsurface: do they focus on a single substrate and exhibit catabolite repression or do they de-repress regulation of all catabolic pathways? Here, we investigated the readiness of Geobacter metallireducens to degrade organic substrates under sessile growth in sediment columns in the presence of a mixed community as a model for aquifers. Three parallel columns were filled with sand and flushed with anoxic medium at a constant inflow (18 ml h-1) of the substrate benzoate (1 mM) with non-limiting nitrate concentrations (30 mM) as electron acceptor. Columns were inoculated with the anaerobic benzoate degrader G. metallireducens. Microbial degradation produced concentration gradients of benzoate toward the column outlet. Metagenomics and label-free metaproteomics were used to detect and quantify the protein expression of G. metallireducens. Bulk benzoate concentrations below 0.2 mM led to increased abundance of catabolic proteins involved in utilization of fermentation products and aromatic compounds including the complete upregulation of the toluene-degrading pathway although toluene was not added to the medium. We propose that under sessile conditions and low substrate concentrations G. metallireducens expresses a specific set of catabolic pathways for preferred substrates, even when these substrates are not present.
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Affiliation(s)
- Sviatlana Marozava
- Institute of Groundwater Ecology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Juliane Merl-Pham
- Research Unit Protein Science, Helmholtz Zentrum München, Neuherberg, Germany
| | - Hubert Müller
- Environmental Microbiology and Biotechnology, University of Duisburg-Essen, Essen, Germany
| | - Rainer U. Meckenstock
- Environmental Microbiology and Biotechnology, University of Duisburg-Essen, Essen, Germany
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Rabus R, Boll M, Golding B, Wilkes H. Anaerobic Degradation of p-Alkylated Benzoates and Toluenes. J Mol Microbiol Biotechnol 2016; 26:63-75. [PMID: 26960059 DOI: 10.1159/000441144] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The anaerobic degradation of 4-alkylbenzoates and 4-alkyltoluenes is to date a rarely reported microbial capacity. The newly isolated Alphaproteobacterium Magnetospirillum sp. strain pMbN1 represents the first pure culture demonstrated to degrade 4-methylbenzoate completely to CO2 in a process coupled to denitrification. Differential proteogenomic studies in conjunction with targeted metabolite analyses and enzyme activity measurements elucidated a specific 4-methylbenzoyl-coenzyme A (CoA) pathway in this bacterium alongside the classical central benzoyl-CoA pathway. Whilst these two pathways are analogous, in the former the p-methyl group is retained and its 4-methylbenzoyl-CoA reductase (MbrCBAD) is phylogenetically distinct from the archetypical class I benzoyl-CoA reductase (BcrCBAD). Subsequent global regulatory studies on strain pMbN1 grown with binary or ternary substrate mixtures revealed benzoate to repress the anaerobic utilization of 4-methylbenzoate and succinate. The shared nutritional property of betaproteobacterial 'Aromatoleum aromaticum' pCyN1 and Thauera sp. strain pCyN2 is the anaerobic degradation of the plant-derived hydrocarbon p-cymene (4-isopropyltoluene) coupled to denitrification. Notably, the two strains employ two different peripheral pathways for the conversion of p-cymene to 4-isopropylbenzoyl-CoA as the possible first common intermediate. In 'A. aromaticum' pCyN1 a putative p-cymene dehydrogenase (CmdABC) is proposed to hydroxylate the benzylic methyl group, which is subsequently further oxidized to the CoA-thioester. In contrast, Thauera sp. strain pCyN2 employs a reaction sequence analogous to the known anaerobic toluene pathway, involving a distinct branching (4-isopropylbenzyl)succinate synthase (IbsABCDEF).
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Affiliation(s)
- Ralf Rabus
- Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University Oldenburg, Oldenburg, Germany
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Saucedo-Lucero JO, Marcos R, Salvador M, Arriaga S, Muñoz R, Quijano G. Treatment of O₂-free toluene emissions by anoxic biotrickling filtration. CHEMOSPHERE 2014; 117:774-780. [PMID: 25461947 DOI: 10.1016/j.chemosphere.2014.10.041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 10/09/2014] [Accepted: 10/11/2014] [Indexed: 06/04/2023]
Abstract
Toluene biotrickling filtration under anoxic denitrifying conditions was evaluated in two identical bioreactors (R1 and R2) operated at liquid recycling rates of 1.3, 2.7 and 5.3 m h−1 and liquid renewal rates of 0 and 0.17 d−1. R1 and R2 achieved a similar maximum elimination capacity (EC ∼30 g m−3 h−1) at the same toluene inlet load (∼50 g m−3 h−1), which was approximately 7 times higher compared with available literature on continuous toluene removal under anoxic conditions. Nevertheless, higher metabolite accumulation was observed in the bioreactor operated without periodical liquid phase renewal (R2), leading to intermittent drops in its toluene removal performance. This is the first work operating an anoxic biotrickling filter at empty bed residence time of 3 min, which is comparable with those employed in conventional aerobic systems. A characterization of the metabolites accumulated in the liquid phase revealed a dynamic metabolite production and degradation.
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Affiliation(s)
- J Octavio Saucedo-Lucero
- Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n, 47011 Valladolid, Spain
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Wöhlbrand L, Jacob JH, Kube M, Mussmann M, Jarling R, Beck A, Amann R, Wilkes H, Reinhardt R, Rabus R. Complete genome, catabolic sub-proteomes and key-metabolites of Desulfobacula toluolica Tol2, a marine, aromatic compound-degrading, sulfate-reducing bacterium. Environ Microbiol 2012; 15:1334-55. [PMID: 23088741 DOI: 10.1111/j.1462-2920.2012.02885.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 08/29/2012] [Accepted: 08/30/2012] [Indexed: 11/30/2022]
Abstract
Among the dominant deltaproteobacterial sulfate-reducing bacteria (SRB), members of the genus Desulfobacula are not only present in (hydrocarbon-rich) marine sediments, but occur also frequently in the anoxic water bodies encountered in marine upwelling areas. Here, we present the 5.2 Mbp genome of Desulfobacula toluolica Tol2, which is the first of an aromatic compound-degrading, marine SRB. The genome has apparently been shaped by viral attacks (e.g. CRISPRs) and its high plasticity is reflected by 163 detected genes related to transposases and integrases, a total of 494 paralogous genes and 24 group II introns. Prediction of the catabolic network of strain Tol2 was refined by differential proteome and metabolite analysis of substrate-adapted cells. Toluene and p-cresol are degraded by separate suites of specific enzymes for initial arylsuccinate formation via addition to fumarate (p-cresol-specific enzyme HbsA represents a new phylogenetic branch) as well as for subsequent modified β-oxidation of arylsuccinates to the central intermediate benzoyl-CoA. Proteogenomic evidence suggests specific electron transfer (EtfAB) and membrane proteins to channel electrons from dehydrogenation of both arylsuccinates directly to the membrane redox pool. In contrast to the known anaerobic degradation pathways in other bacteria, strain Tol2 deaminates phenylalanine non-oxidatively to cinnamate by phenylalanine ammonia-lyase and subsequently forms phenylacetate (both metabolites identified in (13) C-labelling experiments). Benzoate degradation involves CoA activation, reductive dearomatization by a class II benzoyl-CoA reductase and hydrolytic ring cleavage as found in the obligate anaerobe Geobacter metallireducens GS-15. The catabolic sub-proteomes displayed high substrate specificity, reflecting the genomically predicted complex and fine-tuned regulatory network of strain Tol2. Despite the genetic equipment for a TCA cycle, proteomic evidence supports complete oxidation of acetyl-CoA to CO2 via the Wood-Ljungdahl pathway. Strain Tol2 possesses transmembrane redox complexes similar to that of other Desulfobacteraceae members. The multiple heterodisulfide reductase-like proteins (more than described for Desulfobacterium autotrophicum HRM2) may constitute a multifaceted cytoplasmic electron transfer network.
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Affiliation(s)
- Lars Wöhlbrand
- Institute for Chemistry and Biology of Marine Environment (ICBM), Carl von Ossietzky University Oldenburg, Carl-von-Ossietzky-Strasse 9-11, 26111, Oldenburg, Germany
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6
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Lahme S, Harder J, Rabus R. Anaerobic degradation of 4-methylbenzoate by a newly isolated denitrifying bacterium, strain pMbN1. Appl Environ Microbiol 2012; 78:1606-10. [PMID: 22179254 PMCID: PMC3294469 DOI: 10.1128/aem.06552-11] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Accepted: 12/12/2011] [Indexed: 11/20/2022] Open
Abstract
A novel alphaproteobacterium isolated from freshwater sediments, strain pMbN1, degrades 4-methylbenzoate to CO(2) under nitrate-reducing conditions. While strain pMbN1 utilizes several benzoate derivatives and other polar aromatic compounds, it cannot degrade p-xylene or other hydrocarbons. Based on 16S rRNA gene sequence analysis, strain pMbN1 is affiliated with the genus Magnetospirillum.
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Affiliation(s)
- Sven Lahme
- Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University, Oldenburg, Germany
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Jens Harder
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Ralf Rabus
- Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University, Oldenburg, Germany
- Max Planck Institute for Marine Microbiology, Bremen, Germany
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Lahme S, Eberlein C, Jarling R, Kube M, Boll M, Wilkes H, Reinhardt R, Rabus R. Anaerobic degradation of 4-methylbenzoate via a specific 4-methylbenzoyl-CoA pathway. Environ Microbiol 2012; 14:1118-32. [PMID: 22264224 DOI: 10.1111/j.1462-2920.2011.02693.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The pathway for anaerobic degradation of 4-methylbenzoate was studied in the denitrifying alphaproteobacterium Magnetospirillum sp. strain pMbN1. Adaptation studies with whole cells indicated substrate-dependent induction of the capacity to degrade 4-methylbenzoate. Differential protein profiling (2D-DIGE) of 4-methylbenzoate- in comparison with benzoate- or succinate-adapted cells revealed the specific abundance increase of substrate-specific protein sets. Their coding genes form distinct clusters on the genome, two of which were assigned to 4-methylbenzoate and one to benzoate degradation. The predicted functions of the gene products agree with a specific 4-methylbenzoyl-CoA degradation pathway in addition to and analogous to the known anaerobic benzoyl-CoA degradation pathway. In vitro benzoyl-CoA and 4-methylbenzoyl-CoA reductase activities revealed the electron donor and ATP-dependent formation of the corresponding conjugated cyclic dienoyl-CoA/4-methyl-dienoyl-CoA products. The 4-methylbenzoyl-CoA reductase activity was induced in the presence of 4-methylbenzoate. In accordance, metabolite analysis of cultures grown with 4-methylbenzoate tentatively identified 4-methylcyclohex-1,5-diene-1-carboxylate. The 4-methylbenzoate induced genes were assigned to code for the putative 4-methylbenzoyl-CoA reductase; their products display pronounced sequence disparity from the conventional class I benzoyl-CoA reductase, which does not accept substituents at the para-position. Identification of 3-methylglutarate together with the formation of specific proteins for ring cleavage and β-oxidation in 4-methylbenzoate-adapted cells suggest conservation of the methyl group along the specific 4-methylbenzoyl-CoA degradation pathway.
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Affiliation(s)
- Sven Lahme
- Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, Carl-von-Ossietzky-Strasse 9-11, Oldenburg, Germany
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Parales RE, Parales JV, Pelletier DA, Ditty JL. Diversity of microbial toluene degradation pathways. ADVANCES IN APPLIED MICROBIOLOGY 2008; 64:1-73, 2 p following 264. [PMID: 18485280 DOI: 10.1016/s0065-2164(08)00401-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- R E Parales
- Department of Microbiology, University of California, Davis, California 95616, USA
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Langenhoff AA, Nijenhuis I, Tan NC, Briglia M, Zehnder AJ, Schraa G. Characterisation of a manganese-reducing, toluene-degrading enrichment culture. FEMS Microbiol Ecol 2006. [DOI: 10.1111/j.1574-6941.1997.tb00428.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Quesnel D, Nakhla G. Optimization of the aerobic biological treatment of thermophilically treated refractory wastewater. JOURNAL OF HAZARDOUS MATERIALS 2005; 125:221-30. [PMID: 16005148 DOI: 10.1016/j.jhazmat.2005.05.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Revised: 05/19/2005] [Accepted: 05/24/2005] [Indexed: 05/03/2023]
Abstract
A pilot scale conventional activated sludge was operated for over 600 days to study its effectiveness at further remediating the effluent of an existing industrial site's thermophilic biological treatment stage. During the course of the study, the activated sludge was able to further biodegrade the contaminants in the incoming industrial wastewater in terms of both BOD and nitrogen reductions at varying hydraulic and solids retention times, despite elevated concentrations of soluble copper being present. A limiting hydraulic retention time (HRT) for BOD removal of 1.5 days was observed as well as the loss of nitrification occurred at a solids retention time (SRT) of approximately 6 days. Biokinetic coefficients were determined with the maximum rate of substrate utilization per unit mass of microorganisms, k, of 0.14 mgVSS/(mgsBOD-d) and the Monod half velocity constant, K(s), of 9.4 mgsBOD/L. Simultaneous nitrification and denitrification (SND) of the nitrogenous compounds found in this wastewater was observed throughout the majority of the experimentation while the bulk DO in the system was greater than 1 mg/L. The activated sludge was estimated to contain soluble copper on the order of 1 mg/L throughout the course of operation with no apparent detriment to nitrification. Additionally, the activated sludge was able to biologically remove the main solvents found in the influent wastewater. The removals of trace levels of N-nitrosodimethylamine (NDMA) were also observed.
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Affiliation(s)
- David Quesnel
- University of Western Ontario, Department of Chemical & Biochemical Engineering, London, Ont., Canada
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11
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Kniemeyer O, Fischer T, Wilkes H, Glöckner FO, Widdel F. Anaerobic degradation of ethylbenzene by a new type of marine sulfate-reducing bacterium. Appl Environ Microbiol 2003; 69:760-8. [PMID: 12570993 PMCID: PMC143655 DOI: 10.1128/aem.69.2.760-768.2003] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2002] [Accepted: 11/11/2002] [Indexed: 11/20/2022] Open
Abstract
Anaerobic degradation of the aromatic hydrocarbon ethylbenzene was studied with sulfate as the electron acceptor. Enrichment cultures prepared with marine sediment samples from different locations showed ethylbenzene-dependent reduction of sulfate to sulfide and always contained a characteristic cell type that formed gas vesicles towards the end of growth. A pure culture of this cell type, strain EbS7, was isolated from sediment from Guaymas Basin (Gulf of California). Complete mineralization of ethylbenzene coupled to sulfate reduction was demonstrated in growth experiments with strain EbS7. Sequence analysis of the 16S rRNA gene revealed a close relationship between strain EbS7 and the previously described marine sulfate-reducing strains NaphS2 and mXyS1 (similarity values, 97.6 and 96.2%, respectively), which grow anaerobically with naphthalene and m-xylene, respectively. However, strain EbS7 did not oxidize naphthalene, m-xylene, or toluene. Other compounds utilized by strain EbS7 were phenylacetate, 3-phenylpropionate, formate, n-hexanoate, lactate, and pyruvate. 1-Phenylethanol and acetophenone, the characteristic intermediates in anaerobic ethylbenzene degradation by denitrifying bacteria, neither served as growth substrates nor were detectable as metabolites by gas chromatography-mass spectrometry in ethylbenzene-grown cultures of strain EbS7. Rather, (1-phenylethyl)succinate and 4-phenylpentanoate were detected as specific metabolites in such cultures. Formation of these intermediates can be explained by a reaction sequence involving addition of the benzyl carbon atom of ethylbenzene to fumarate, carbon skeleton rearrangement of the succinate moiety (as a thioester), and loss of one carboxyl group. Such reactions are analogous to those suggested for anaerobic n-alkane degradation and thus differ from the initial reactions in anaerobic ethylbenzene degradation by denitrifying bacteria which employ dehydrogenations.
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Affiliation(s)
- Olaf Kniemeyer
- Max-Planck-Institut für Marine Mikrobiologie, D-28359 Bremen, Germany
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12
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Abstract
Benzene is biodegraded in the absence of oxygen under a variety of terminal electron-accepting conditions. However, the mechanism by which anaerobic benzene degradation occurs is unclear. Phenol and benzoate have been consistently detected as intermediates of anaerobic benzene degradation, suggesting that the hydroxylation of benzene to phenol is one of the initial steps in anaerobic benzene degradation. The conversion of phenol to benzoate could then occur by the carboxylation of phenol to form 4-hydroxybenzoate followed by the reductive removal of the hydroxyl group to form benzoate. 13C-Labeling studies suggest that the carboxyl carbon of benzoate is derived from one of the carbons of benzene. Although the fumarate addition reaction is commonly used to activate many hydrocarbons for anaerobic degradation, the large activation energy required to remove hydrogen from the benzene ring argues against such an approach for anaerobic benzene metabolism. The alkylation of benzene to toluene has been detected in several mammalian tissues, and offers an interesting alternate hypothesis for anaerobic benzene degradation in microbial systems. In support of this, anaerobic benzene degradation by Dechloromonas strain RCB, the only known species to degrade benzene in the absence of oxygen, is stimulated by the addition of vitamin B12 and inhibited by the addition of propyl iodide which is consistent with the involvement of a corrinoid enzymatic step. Alkylation of benzene to toluene is also consistent with labeling data that suggests that the carboxyl carbon of benzoate is derived from one of the benzene carbons. However, it is difficult to envision how phenol would be formed if benzene is alkylated to toluene. As such, it is possible that diverse mechanisms for anaerobic benzene degradation may be operative in different anaerobic microorganisms.
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Affiliation(s)
- John D Coates
- Department of Plant and Microbial Biology, University College Berkeley, Berkeley, CA 94720, USA.
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Beller HR, Edwards EA. Anaerobic toluene activation by benzylsuccinate synthase in a highly enriched methanogenic culture. Appl Environ Microbiol 2000; 66:5503-5. [PMID: 11097937 PMCID: PMC92491 DOI: 10.1128/aem.66.12.5503-5505.2000] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2000] [Accepted: 10/02/2000] [Indexed: 11/20/2022] Open
Abstract
Permeabilized cells of a highly enriched, toluene-mineralizing, methanogenic culture catalyzed the addition of toluene to fumarate to form benzylsuccinate under anaerobic conditions. The specific in vitro rate of benzylsuccinate formation was >85% of the specific in vivo rate of toluene consumption. This is the first report of benzylsuccinate synthase activity in a methanogenic culture; the activity has previously been reported to occur in denitrifying, sulfate-reducing, and anoxygenic phototrophic bacteria.
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Affiliation(s)
- H R Beller
- Lawrence Livermore National Laboratory, Livermore, California 94551-0808, USA.
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Krieger CJ, Beller HR, Reinhard M, Spormann AM. Initial reactions in anaerobic oxidation of m-xylene by the denitrifying bacterium Azoarcus sp. strain T. J Bacteriol 1999; 181:6403-10. [PMID: 10515931 PMCID: PMC103776 DOI: 10.1128/jb.181.20.6403-6410.1999] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/1999] [Accepted: 08/09/1999] [Indexed: 11/20/2022] Open
Abstract
The initial enzymatic steps in anaerobic m-xylene oxidation were studied in Azoarcus sp. strain T, a denitrifying bacterium capable of mineralizing m-xylene via 3-methylbenzoate. Permeabilized cells of m-xylene-grown Azoarcus sp. strain T catalyzed the addition of m-xylene to fumarate to form (3-methylbenzyl)succinate. In the presence of succinyl coenzyme A (CoA) and nitrate, (3-methylbenzyl)succinate was oxidized to E-(3-methylphenyl)itaconate (or a closely related isomer) and 3-methylbenzoate. Kinetic studies conducted with permeabilized cells and whole-cell suspensions of m-xylene-grown Azoarcus sp. strain T demonstrated that the specific rate of in vitro (3-methylbenzyl)succinate formation accounts for at least 15% of the specific rate of in vivo m-xylene consumption. Based on these findings, we propose that Azoarcus sp. strain T anaerobically oxidizes m-xylene to 3-methylbenzoate (or its CoA thioester) via (3-methylbenzyl)succinate and E-(3-methylphenyl)itaconate (or its CoA thioester) in a series of reactions that are analogous to those recently proposed for anaerobic toluene oxidation to benzoyl-CoA. A deuterium kinetic isotope effect was observed in the (3-methylbenzyl)succinate synthase reaction (and the benzylsuccinate synthase reaction), suggesting that a rate-determining step in this novel fumarate addition reaction involves breaking a C-H bond.
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Affiliation(s)
- C J Krieger
- Environmental Engineering, Department of Civil Engineering, Stanford University, Stanford, California 94305-4020, USA
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Harms G, Zengler K, Rabus R, Aeckersberg F, Minz D, Rosselló-Mora R, Widdel F. Anaerobic oxidation of o-xylene, m-xylene, and homologous alkylbenzenes by new types of sulfate-reducing bacteria. Appl Environ Microbiol 1999; 65:999-1004. [PMID: 10049854 PMCID: PMC91135 DOI: 10.1128/aem.65.3.999-1004.1999] [Citation(s) in RCA: 162] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/1998] [Accepted: 10/16/1998] [Indexed: 11/20/2022] Open
Abstract
Various alkylbenzenes were depleted during growth of an anaerobic, sulfate-reducing enrichment culture with crude oil as the only source of organic substrates. From this culture, two new types of mesophilic, rod-shaped sulfate-reducing bacteria, strains oXyS1 and mXyS1, were isolated with o-xylene and m-xylene, respectively, as organic substrates. Sequence analyses of 16S rRNA genes revealed that the isolates affiliated with known completely oxidizing sulfate-reducing bacteria of the delta subclass of the class Proteobacteria. Strain oXyS1 showed the highest similarities to Desulfobacterium cetonicum and Desulfosarcina variabilis (similarity values, 98.4 and 98.7%, respectively). Strain mXyS1 was less closely related to known species, the closest relative being Desulfococcus multivorans (similarity value, 86.9%). Complete mineralization of o-xylene and m-xylene was demonstrated in quantitative growth experiments. Strain oXyS1 was able to utilize toluene, o-ethyltoluene, benzoate, and o-methylbenzoate in addition to o-xylene. Strain mXyS1 oxidized toluene, m-ethyltoluene, m-isoproyltoluene, benzoate, and m-methylbenzoate in addition to m-xylene. Strain oXyS1 did not utilize m-alkyltoluenes, whereas strain mXyS1 did not utilize o-alkyltoluenes. Like the enrichment culture, both isolates grew anaerobically on crude oil with concomitant reduction of sulfate to sulfide.
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Affiliation(s)
- G Harms
- Max-Planck-Institut für Marine Mikrobiologie, D-28359 Bremen, Germany
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Londry KL, Fedorak PM, Suflita JM. Anaerobic Degradation of m-Cresol by a Sulfate-Reducing Bacterium. Appl Environ Microbiol 1997; 63:3170-5. [PMID: 16535673 PMCID: PMC1389228 DOI: 10.1128/aem.63.8.3170-3175.1997] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
m-Cresol metabolism under sulfate-reducing conditions was studied with a pure culture of Desulfotomaculum sp. strain Groll. Previous studies with a sulfate-reducing consortium indicated that m-cresol was degraded via an initial para-carboxylation reaction. However, 4-hydroxy-2-methylbenzoic acid was not degraded by strain Groll, and no evidence for ring carboxylation of m-cresol was found. Strain Groll readily metabolized the putative metabolites of a methyl group oxidation pathway, including 3-hydroxybenzyl alcohol, 3-hydroxybenzaldehyde, 3-hydroxybenzoic acid, and benzoic acid. Degradation of these compounds preceded and inhibited m-cresol decay. 3-Hydroxybenzoic acid was detected in cultures that received either m-cresol or 3-hydroxybenzyl alcohol, and trace amounts of benzoic acid were detected in m-cresol-degrading cultures. Therefore, we propose that strain Groll metabolizes m-cresol by a methyl group oxidation pathway which is an alternate route for the catabolism of this compound under sulfate-reducing conditions.
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Beller HR, Spormann AM. Anaerobic activation of toluene and o-xylene by addition to fumarate in denitrifying strain T. J Bacteriol 1997; 179:670-6. [PMID: 9006019 PMCID: PMC178746 DOI: 10.1128/jb.179.3.670-676.1997] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Anaerobic assays conducted with strain T, a denitrifying bacterium capable of mineralizing toluene to carbon dioxide, demonstrated that toluene-grown, permeabilized cells catalyzed the addition of toluene to fumarate to form benzylsuccinate. This reaction was not dependent on the presence of coenzyme A (CoA) or ATP. In the presence of CoA, formation of E-phenylitaconate from benzylsuccinate was also observed. Kinetic studies demonstrated that the specific rate of benzylsuccinate formation from toluene and fumarate in assays with permeabilized cells was >30% of the specific rate of toluene consumption in whole-cell suspensions with nitrate; this observation suggests that benzylsuccinate formation may be the first reaction in anaerobic toluene degradation by strain T. Use of deuterium-labeled toluene and gas chromatography-mass spectrometry indicated that the H atom abstracted from the toluene methyl group during addition to fumarate was retained in the succinyl moiety of benzylsuccinate. In this study, no evidence was found to support previously proposed reactions of toluene with acetyl-CoA or succinyl-CoA. Toluene-grown, permeabilized cells of strain T also catalyzed the addition of o-xylene to fumarate to form (2-methylbenzyl)succinate. o-Xylene is not a growth substrate for strain T, and its transformation was probably cometabolic. With the exception of specific reaction rates, the observed characteristics of the toluene-fumarate addition reaction (i.e., retention of a methyl H atom and independence from CoA and ATP) also apply to the o-xylene-fumarate addition reaction. Thus, addition to fumarate may be a biochemical strategy to anaerobically activate a range of methylbenzenes.
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Affiliation(s)
- H R Beller
- Environmental Engineering and Science, Department of Civil Engineering, Stanford University, California 94305-4020, USA
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Abstract
Anaerobic biodegradation of aliphatic and aromatic hydrocarbons is a promising alternative to aerobic biodegradation treatments in bioremediation processes. It is now proven that, besides toluene, benzene and ethylbenzene can be oxidized under anaerobic redox conditions. Anaerobic bacteria have also been shown capable of utilizing substrates not only in the pure form, but also in complex hydrocarbon mixtures, such as crude oil. In addition, crucial steps in anaerobic treatment processes have been studied in vitro to better understand the enzymes involved in monoaromatic hydrocarbon degradation. Knowledge remains incomplete, however, about the anaerobic degradation of aliphatic and polycyclic aromatic hydrocarbons.
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Affiliation(s)
- C Holliger
- Swiss Federal Institute for Environmental Science and Technology (EAWAG), Limnological Research Center, Kastanienbaum Switzerland.
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Rabus R, Widdel F. Conversion studies with substrate analogues of toluene in a sulfate-reducing bacterium, strain Tol2. Arch Microbiol 1995; 164:448-51. [PMID: 8588748 DOI: 10.1007/bf02529744] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Anaerobic toluene oxidation by the sulfate-reducing bacterium, strain Tol2 (proposed name Desulfobacula toluolica) was specifically inhibited by benzyl alcohol when added at concentrations around 500 microM. Benzyl alcohol added at lower, non-inhibitory concentrations (around 5 microM) was not oxidized by active cells pregrown on toluene, indicating that the alcohol is not a free intermediate of toluene metabolism in the sulfate reducer. Conversion of p-xylene in toluene-metabolizing cells to p-methylbenzoate as dead-end product suggests that the sulfate reducer, like denitrifiers, initiates toluene oxidation at the methyl group.
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Affiliation(s)
- R Rabus
- Max-Planck-Institut für Marine Mikrobiologie, Fahrenheitstrasse 1, D-28359 Bremen, Germany
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Biegert T, Altenschmidt U, Eckerskorn C, Fuchs G. Purification and properties of benzyl alcohol dehydrogenase from a denitrifying Thauera sp. Arch Microbiol 1995; 163:418-23. [PMID: 7575097 DOI: 10.1007/bf00272130] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Toluene and related aromatic compounds are anaerobically degraded by the denitrifying bacterium Thauera sp. strain K172 via oxidation to benzoyl-CoA. The postulated initial step is methylhydroxylation of toluene to benzyl alcohol, which is either a free or enzyme-bound intermediate. Cells grown with toluene or benzyl alcohol contained benzyl alcohol dehydrogenase, which is possibly the second enzyme in the proposed pathway. The enzyme was purified from benzyl-alcohol-grown cells and characterized. It has many properties in common with benzyl alcohol dehydrogenase from Acinetobacter and Pseudomonas species. The enzyme was active as a homotetramer of 160 kDa, with subunits of 40 kDa. It was NAD(+)-specific, had an alkaline pH optimum, and was inhibited by thiol-blocking agents. No evidence for a bound cofactor was obtained. Various benzyl alcohol analogues served as substrates, whereas non-aromatic alcohols were not oxidized. The N-terminal amino acid sequence indicates that the enzyme belongs to the class of long-chain Zn(2+)-dependent alcohol dehydrogenases, although it appears not to contain a metal ion that can be removed by complexing agents.
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