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).

1.
Barragán MJ, Blázquez B, Zamarro MT, Mancheño JM, García JL, Díaz E, Carmona M: BzdR, a repressor that controls the anaerobic catabolism of benzoate in Azoarcus sp. CIB, is the first member of a new subfamily of transcriptional regulators. J Biol Chem 2005;280:10683-10694.
[PubMed]
2.
Beller HR, Spormann AM, Sharma PK, Cole JR, Reinhard M: Isolation and characterization of a novel toluene-degrading, sulfate-reducing bacterium. Appl Environ Microbiol 1996;62:1188-1196.
[PubMed]
3.
Bharadwaj VS, Dean AM, Maupin CM: Insights into the glycyl radical enzyme active site of benzylsuccinate synthase: a computational study. J Am Chem Soc 2013;135:12279-12288.
[PubMed]
4.
Biegert T, Fuchs G: Anaerobic oxidation of toluene (analogues) to benzoate (analogues) by whole cells and by cell extracts of a denitrifying Thauera sp. Arch Microbiol 1995;163:407-417.
5.
Birch AJ: Reduction by dissolving metals. Part I. J Chem Soc 1944;430-436.
6.
Boll M: Dearomatizing benzene ring reductases. J Mol Microbiol Biotechnol 2005;10:132-142.
[PubMed]
7.
Boll M, Fuchs G: Benzoyl-coenzyme A reductase (dearomatizing), a key enzyme of anaerobic aromatic metabolism. ATP dependence of the reaction, purification and some properties of the enzyme from Thauera aromatica strain K172. Eur J Biochem 1995;234:921-933.
[PubMed]
8.
Boll M, Fuchs G, Lowe DJ: Single turnover EPR studies of benzoyl-CoA reductase. Biochemistry 2001;40:7612-7620.
[PubMed]
9.
Boll M, Fuchs G, Meier C, Trautwein A, Lowe DJ: Epr and Mossbauer studies of benzoyl-CoA reductase. J Biol Chem 2000;275:31857-31868.
[PubMed]
10.
Boll M, Löffler C, Morris BE, Kung JW: Anaerobic degradation of homocyclic aromatic compounds via arylcarboxyl-coenzyme A esters: organisms, strategies and key enzymes. Environ Microbiol 2014;16:612-267.
[PubMed]
11.
Brackmann R, Fuchs G: Enzymes of anaerobic metabolism of phenolic compounds. 4-hydroxybenzoyl-CoA reductase (dehydroxylating) from a denitrifying Pseudomonas species. Eur J Biochem 1993;213:563-571.
[PubMed]
12.
Breese K, Boll M, Alt-Mörbe J, Schägger H, Fuchs G: Genes coding for the benzoyl-CoA pathway of anaerobic aromatic metabolism in the bacterium Thauera aromatica. Eur J Biochem 1998;256:148-154.
[PubMed]
13.
Buckel W, Kung JW, Boll M: The benzoyl-coenzyme A reductase and 2-hydroxyacyl-coenzyme A dehydratase radical enzyme family. Chembiochem 2014;15:2188-2194.
[PubMed]
14.
Carmona M, Zamarro MT, Blázquez B, Durante-Rodríguez G, Juárez JF, Valderrama JA, Barragán MJL, García JL, Díaz E: Anaerobic catabolism of aromatic compounds: a genetic and genomic view. Microbiol Mol Biol Rev 2009;73:71-133.
[PubMed]
15.
Cunane LM, Chen Z-W, Shamala N, Mathews FS, Cronin CN, McIntire WS: Structures of the flavocytochrome p-cresol methylhydroxylase and its enzyme-substrate complex: gated substrate entry and proton relays support the proposed catalytic mechanism. J Mol Biol 2000;295:357-374.
[PubMed]
16.
DiLabio GA, Ingold KU: Solvolysis of para-substituted cumyl chlorides. Brown and Okamoto's electrophilic substituent constants revisited using continuum solvent models. J Org Chem 2004;69:1620-1624.
[PubMed]
17.
Durante-Rodríguez G, Zamarro MT, García JL, Díaz E, Carmona M: Oxygen-dependent regulation of the central pathway for the anaerobic catabolism of aromatic compounds in Azoarcus sp. strain CIB. J Bacteriol 2006;188:2343-2354.
[PubMed]
18.
Eaton RW: p-Cymene catabolic pathway in Pseudomonas putida F1: cloning and characterization of DNA encoding conversion of p-cymene to p-cumate. J Bacteriol 1997;179:3171-3180.
[PubMed]
19.
Fuchs G, Boll M, Heider J: Microbial degradation of aromatic compounds - from one strategy to four. Nat Rev Microbiol 2011;9:803-816.
[PubMed]
20.
Funk MA, Judd ET, Marsh EN, Elliott SJ, Drennan CL: Structures of benzylsuccinate synthase elucidate roles of accessory subunits in glycyl radical enzyme activation and activity. Proc Natl Acad Sci USA 2014;111:10161-10166.
[PubMed]
21.
Häner A, Höhener P, Zeyer J: Degradation of p-xylene by a denitrifying enrichment culture. Appl Environ Microbiol 1995;61:3185-3188.
[PubMed]
22.
Harms G, Rabus R, Widdel F: Anaerobic oxidation of the aromatic plant hydrocarbon p-cymene by newly isolated denitrifying bacteria. Arch Microbiol 1999;172:303-312.
[PubMed]
23.
Heider J, Boll M, Breese K, Breinig S, Ebenau-Jehle C, Feil U, Gad'on N, Laempe D, Leuthner B, Mohamed ME, Schneider S, Burchhardt G, Fuchs G: Differential induction of enzymes involved in anaerobic metabolism of aromatic compounds in the denitrifying bacterium Thauera aromatica. Arch Microbiol 1998;170:120-131.
[PubMed]
24.
Higashioka Y, Kojima H, Fukui M: Isolation and characterization of novel sulfate-reducing bacterium capable of anaerobic degradation of p-xylene. Microbes Environ 2012;27:273-277.
[PubMed]
25.
Hopper DJ: The hydroxylation of p-cresol and its conversion to p-hydroxybenzaldehyde in Pseudomonas putida. Biochem Biophys Res Commun 1976;69:462-468.
[PubMed]
26.
Juárez JF, Liu H, Zamarro MT, McMahon S, Liu H, Naismith JH, Eberlein C, Boll M, Carmona M, Díaz E: Unraveling the specific regulation of the central pathway for anaerobic degradation of 3-methylbenzoate. J Biol Chem 2015;290:12165-12183.
[PubMed]
27.
Juárez JF, Zamarro MT, Eberlein C, Boll M, Carmona M, Díaz E: Characterization of the mbd cluster encoding the anaerobic 3-methylbenzoyl-CoA central pathway. Environ Microbiol 2013;15:148-166.
[PubMed]
28.
Kloer DP, Hagel C, Heider J, Schulz GE: Crystal structure of ethylbenzene dehydrogenase from Aromatoleumaromaticum. Structure 2006;14:1377-1388.
[PubMed]
29.
Knack D, Hagel C, Szaleniec M, Dudzik A, Salwinski A, Heider J: Substrate and inhibitor spectra of ethylbenzene dehydrogenase: perspectives on application potential and catalytic mechanism. Appl Environ Microbiol 2012;78:6475-6482.
[PubMed]
30.
Kniemeyer O, Heider J: Ethylbenzene dehydrogenase, a novel hydrocarbon-oxidizing molybdenum/iron-sulfur/heme enzyme. J Biol Chem 2001;276:21381-21386.
[PubMed]
31.
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;69:760-768.
[PubMed]
32.
Kube M, Heider J, Hufnagel P, Kühner S, Beck A, Reinhardt R, Rabus R: Genes involved in the anaerobic degradation of toluene in a denitrifying bacterium, strain EbN1. Arch Microbiol 2004;181:182-184.
[PubMed]
33.
Kung JW, Baumann S, von Bergen M, Müller M, Hagedoorn PL, Hagen WR, Boll M: Reversible biological Birch reduction at an extremely low redox potential. J Am Chem Soc 2010;132:9850-9856.
[PubMed]
34.
Kuntze K, Kiefer P, Baumann S, Seifert J, von Bergen M, Vorholt JA, Boll M: Enzymes involved in the anaerobic degradation of meta-substituted halobenzoates. Mol Microbiol 2011a;82:758-769.
[PubMed]
35.
Kuntze K, Vogt C, Richnow HH, Boll M: Combined application of PCR-based functional assays for the detection of aromatic-compound-degrading anaerobes. Appl Environ Microbiol 2011b;77:5056-5061.
[PubMed]
36.
Laempe D, Jahn M, Breese K, Schagger H, Fuchs G: Anaerobic metabolism of 3-hydroxybenzoate by the denitrifying bacterium Thauera aromatica. J Bacteriol 2001;183:968-979.
[PubMed]
37.
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 2012a;14:1118-1132.
[PubMed]
38.
Lahme S, Harder J, Rabus R: Anaerobic degradation of 4-methylbenzoate by a new denitrifying bacterium, strain pMbN1. Appl Environ Microbiol 2012b;78:1606-1610.
[PubMed]
39.
Lahme S, Trautwein K, Strijkstra A, Dörries M, Wöhlbrand L, Rabus R: Benzoate mediates the simultaneous repression of anaerobic 4-methylbenzoate and succinate utilization in Magnetospirillum sp. strain pMbN1. BMC Microbiology 2014;14:269.
[PubMed]
40.
Leuthner B, Heider J: Anaerobic toluene catabolism of Thauera aromatica: the bbs operon codes for enzymes of β-oxidation of the intermediate benzylsuccinate. J Bacteriol 2000;182:272-277.
[PubMed]
41.
Lochmeyer C, Koch J, Fuchs G: Anaerobic degradation of 2-aminobenzoic acid (anthranilic acid) via benzoyl-coenzyme A (CoA) and cyclohex-1-enecarboxyl-CoA in a denitrifying bacterium. J Bacteriol 1992;174:3621-3628.
[PubMed]
42.
Löffler C, Kuntze K, Vazquez JR, Rugor A, Kung JW, Bottcher A, Boll M: Occurrence, genes and expression of the W/Se-containing class II benzoyl-coenzyme A reductases in anaerobic bacteria. Environ Microbiol 2011;13:696-709.
[PubMed]
43.
López Barragán MJ, Carmona M, Zamarro MT, Thiele B, Boll M, Fuchs G, García JL, Díaz E: The bzd gene cluster, coding for anaerobic benzoate catabolism, in Azoarcus sp. strain CIB. J Bacteriol 2004;186:5762-5774.
[PubMed]
44.
McMillen DF, Golden DM: Hydrocarbon bond dissociation energies. Ann Rev Phys Chem 1982;33:493-532.
45.
Möbitz H, Boll M: A Birch-like mechanism in enzymatic benzoyl-CoA reduction: a kinetic study of substrate analogues combined with an ab initio model. Biochemistry 2002;41:1752-1758.
[PubMed]
46.
Morasch B, Meckenstock RU: Anaerobic degradation of p-xylene by a sulfate-reducing enrichment culture. Curr Microbiol 2005;51:127-130.
[PubMed]
47.
Pérez-Pantoja D, González B, Pieper DH: Aerobic degradation of aromatic hydrocarbons; in Timmis KN (ed): Handbook of Hydrocarbon and Lipid Microbiology. Berlin, Springer, 2010, pp 800-837.
48.
Pérez-Pantoja D, Leiva-Novoa P, Donoso RA, Little C, Godoy M, Pieper DH, González B: Hierarchy of carbon source utilization in soil bacteria: hegemonic preference for benzoate in complex aromatic compound mixtures degraded by Cupriavidus pinatubonensis strain JMP134. Appl Environ Microbiol 2015;81:3914-3924.
[PubMed]
49.
Rabus R: Biodegradation of hydrocarbons under anoxic conditions; in Ollivier B, Magot M (eds): Petroleum Microbiology. Washington, ASM Press, 2005, pp 277-299.
50.
Rabus R, Widdel F: Conversion studies with substrate analogues of toluene in a sulfate-reducing bacterium, strain Tol2. Arch Microbiol 1995;164:448-451.
[PubMed]
51.
Rabus R, Fukui M, Wilkes H, Widdel F: Degradative capacities and 16S rRNA-targeted whole-cell hybridization of sulfate-reducing bacteria in an anaerobic enrichment culture utilizing alkylbenzenes from crude oil. Appl Environ Microbiol 1996;62:3605-3613.
[PubMed]
52.
Rabus R, Kube M, Beck A, Widdel F, Reinhardt R: Genes involved in the anaerobic degradation of ethylbenzene in a denitrifying bacterium, strain EbN1. Arch Microbiol 2002,178:506-516.
[PubMed]
53.
Rabus R, Kube M, Heider J, Beck A, Heitmann K, Widdel F, Reinhardt R: The genome sequence of an anaerobic aromatic-degrading denitrifying bacterium, strain EbN1. Arch Microbiol 2005;183:27-36.
[PubMed]
54.
Rabus R, Trautwein K, Wöhlbrand L: Towards habitat-oriented systems biology of ‘Aromatoleum aromaticum' EbN1: chemical sensing, catabolic network modulation and growth control in anaerobic aromatic compound degradation. Appl Microbiol Biotechnol 2014;98:3371-3388.
[PubMed]
55.
Rabus R, Wilkes H, Schramm A, Harms G, Behrends A, Amann R, Widdel F: Anaerobic utilization of alkylbenzenes and n-alkanes from crude oil in an enrichment culture of denitrifying bacteria affiliating with the β-subclass of Proteobacteria. Environ Microbiol 1999;1:145-157.
[PubMed]
56.
Rotaru AE, Probian C, Wilkes H, Harder J: Highly enriched Betaproteobacteria growing anaerobically with p-xylene and nitrate. FEMS Microbiol Ecol 2010;71:460-468.
[PubMed]
57.
Schmid G, Rene SB, Boll M: Enzymes of the benzoyl-coenzyme A degradation pathway in the hyperthermophilic archaeon Ferroglobus placidus. Environ Microbiol 2015; 17:3289-3300.
[PubMed]
58.
Shinoda Y, Akagi J, Uchihashi Y, Hiraishi A, Yukawa H, Yurimoto H, Sakai Y, Kato N: Anaerobic degradation of aromatic compounds by Magnetospirillum strains: isolation and degradation genes. Biosci Biotechnol Biochem 2005;69:1483-1491.
[PubMed]
59.
Strijkstra A, Trautwein K, Jarling R, Wöhlbrand L, Dörries M, Reinhardt R, Drozdowska M, Golding BT, Wilkes H, Rabus R: Anaerobic activation of p-cymene in denitrifying Betaproteobacteria: methyl group hydroxylation versus addition to fumarate. Appl Environ Microbiol 2014;80:7592-7603.
[PubMed]
60.
Szaleniec M, Borowski T, Schühle K, Witko M, Heider J: Ab initio modeling of ethylbenzene dehydrogenase reaction mechanism. J Am Chem Soc 2010;132:6014-6024.
[PubMed]
61.
Szaleniec M, Salwinski A, Borowski T, Heider J, Witko M: Quantum chemical modeling studies of ethylbenzene dehydrogenase activity. Int J Quantum Chem 2012;112:1990-1999.
62.
Trautwein K, Grundmann O, Wöhlbrand L, Eberlein C, Boll M, Rabus R: Benzoate mediates repression of C4-dicarboxylate utilization in ‘Aromatoleum aromaticum' EbN1. J Bacteriol 2012;194:518-528.
[PubMed]
63.
Valderrama JA, Shingler V, Carmona M, Díaz E: AccR is a master regulator involved in carbon catabolite repression of the anaerobic catabolism of aromatic compounds in Azoarcus sp. CIB. J Biol Chem 2014;289:1892-1904.
[PubMed]
64.
von Netzer F, Pilloni G, Kleindienst S, Krüger M, Knittel K, Gründger F, Lueders T: Enhanced gene detection assays for fumarate-adding enzymes allow uncovering of anaerobic hydrocarbon degraders in terrestrial and marine systems. Appl Environ Microbiol 2013;79:543-552.
[PubMed]
65.
Weinert T, Huwiler SG, Kung JW, Weidenweber S, Hellwig P, Stärk H-J, Biskup T, Cotelesage JJH, George GN, Ermler U, Boll M: Structural basis of enzymatic benzene ring reduction. Nature Chem Biol 2015;11:815.
[PubMed]
66.
Widdel F, Knittel K, Galushko A: Anaerobic hydrocarbon-degrading microorganisms: an overview; in Timmis KN (ed): Handbook of hydrocarbon and lipid microbiology. Berlin, Springer, 2010, pp 1997-2021.
67.
Wilkes H, Schwarzbauer J: Hydrocarbons: an introduction to structure, physico-chemical properties and natural occurrence; in Timmis KN (ed): Handbook of Hydrocarbon and Lipid Microbiology. Berlin, Springer, 2010, pp 5-48.
68.
Wilkes H, Boreham C, Harms G, Zengler K, Rabus R: Anaerobic degradation and carbon isotopic fractionation of alkylbenzenes in crude oil by sulphate-reducing bacteria. Organ Geochem 2000;31:101-115.
69.
Wöhlbrand L, 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 2013;15:1334-1355.
[PubMed]
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