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Dinh DM, Thomas LM, Karr EA. Crystal structure of a putative 3-hydroxypimelyl-CoA dehydrogenase, Hcd1, from Syntrophus aciditrophicus strain SB at 1.78 Å resolution. Acta Crystallogr F Struct Biol Commun 2023; 79:151-158. [PMID: 37227375 PMCID: PMC10231260 DOI: 10.1107/s2053230x23004399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 05/20/2023] [Indexed: 05/26/2023] Open
Abstract
Syntrophus aciditrophicus strain SB is a model syntroph that degrades benzoate and alicyclic acids. The structure of a putative 3-hydroxypimelyl-CoA dehydrogenase from S. aciditrophicus strain SB (SaHcd1) was resolved at 1.78 Å resolution. SaHcd1 contains sequence motifs and structural features that belong to the short-chain dehydrogenase/reductase (SDR) family of NADPH-dependent oxidoreductases. SaHcd1 is proposed to concomitantly reduce NAD+ or NADP+ to NADH or NADPH, respectively, while converting 3-hydroxypimelyl-CoA to 3-oxopimeyl-CoA. Further enzymatic studies are needed to confirm the function of SaHcd1.
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Affiliation(s)
- David M. Dinh
- Department of Microbiology and Plant Biology, University of Oklahoma, 770 Van Vleet Oval, Norman, OK 73019, USA
- Price Family Foundation Institute of Structural Biology, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA
| | - Leonard M. Thomas
- Price Family Foundation Institute of Structural Biology, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA
| | - Elizabeth A. Karr
- Department of Microbiology and Plant Biology, University of Oklahoma, 770 Van Vleet Oval, Norman, OK 73019, USA
- Price Family Foundation Institute of Structural Biology, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA
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Huang R, Romero P, Belanche A, Ungerfeld E, Yanez-Ruiz D, Morgavi D, Popova M. Evaluating the effect of phenolic compounds as hydrogen acceptors when ruminal methanogenesis is inhibited in vitro – Part 1. Dairy cows. Animal 2023; 17:100788. [PMID: 37087996 DOI: 10.1016/j.animal.2023.100788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 03/09/2023] [Accepted: 03/13/2023] [Indexed: 03/31/2023] Open
Abstract
Some antimethanogenic feed additives for ruminants promote rumen dihydrogen (H2) accumulation potentially affecting the optimal fermentation of diets. We hypothesised that combining an H2 acceptor with a methanogenesis inhibitor can decrease rumen H2 build-up and improve the production of metabolites that can be useful for the host ruminant. We performed three in vitro incubation experiments using rumen fluid from lactating Holstein cows: Experiment 1 examined the effect of phenolic compounds (phenol, catechol, resorcinol, hydroquinone, pyrogallol, phloroglucinol, and gallic acid) at 0, 2, 4, and 6 mM on ruminal fermentation for 24 h; Experiment 2 examined the combined effect of each phenolic compound from Experiment 1 at 6 mM with two different methanogenesis inhibitors (Asparagopsis taxiformis or 2-bromoethanesulfonate (BES)) for 24 h incubation; Experiment 3 examined the effect of a selected phenolic compound, phloroglucinol, with or without BES over a longer term using sequential incubations for seven days. Results from Experiment 1 showed that phenolic compounds, independently of the dose, did not negatively affect rumen fermentation, whereas results from Experiment 2 showed that phenolic compounds did not decrease H2 accumulation or modify CH4 production when methanogenesis was decreased by up to 75% by inhibitors. In Experiment 3, after three sequential incubations, phloroglucinol combined with BES decreased H2 accumulation by 72% and further inhibited CH4 production, compared to BES alone. Interestingly, supplementation with phloroglucinol (alone or in combination with the CH4 inhibitor) decreased CH4 production by 99% and the abundance of methanogenic archaea, with just a nominal increase in H2 accumulation. Supplementation of phloroglucinol also increased total volatile fatty acid (VFA), acetate, butyrate, and total gas production, and decreased ammonia concentration. This study indicates that some phenolic compounds, particularly phloroglucinol, which are naturally found in plants, could improve VFA production, decrease H2 accumulation and synergistically decrease CH4 production in the presence of antimethanogenic compounds.
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3
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Tang G, Li B, Zhang B, Wang C, Zeng G, Zheng X, Liu C. Dynamics of dissolved organic matter and dissolved organic nitrogen during anaerobic/anoxic/oxic treatment processes. BIORESOURCE TECHNOLOGY 2021; 331:125026. [PMID: 33812138 DOI: 10.1016/j.biortech.2021.125026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/13/2021] [Accepted: 03/16/2021] [Indexed: 06/12/2023]
Abstract
With Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and fluorescence spectroscopy, this study investigated the transformation of dissolved organic matter (DOM) and nitrogen (DON) during the widely-applied anaerobic/anoxic/oxic (A2O) processes to provide molecular insights into the removal, generation, and reduction of DOM/DON species in different biological treatment units. Results indicated that the anaerobic process decomposed the macromolecules of influent DOM/DON and decreased their mass. The anoxic process denitrified DON and generated DOM, as indicated by the decreased molecule number of CHON and CHONS and the increased CHO and CHOS species, as well as the increased overall DOM intensities. DOM mineralization and ammonia nitrogen-DON conversion occurred in the oxic process. Aromaticity and unsaturation degree increased slightly after the A2O processes, which was correlated with the relative abundance of Proteobacteria (positively) and Bacteroidetes (negatively). The results have strong implications to the understanding of DOM/DON dynamics in wastewater treatment plants.
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Affiliation(s)
- Gang Tang
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, PR China
| | - Binrui Li
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, PR China; School of Environment, China University of Geosciences, Wuhan, 430074, PR China
| | - Bowei Zhang
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, PR China
| | - Chen Wang
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, PR China
| | - Guangci Zeng
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, PR China
| | - Xing Zheng
- State Key Laboratory of Eco-hydraulics in Northwest Arid Region, Xi'an University of Technology, Xi'an, 710048, PR China
| | - Chongxuan Liu
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, PR China.
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Jha P, Schmidt S. Reappraisal of chemical interference in anaerobic digestion processes. RENEWABLE AND SUSTAINABLE ENERGY REVIEWS 2017; 75:954-971. [DOI: 10.1016/j.rser.2016.11.076] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
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Han N, Park SY, Kim SY, Yoo MY, Paik HD, Lim SD. Short communication: Change of naturally occurring benzoic acid during skim milk fermentation by commercial cheese starters. J Dairy Sci 2016; 99:8633-8637. [DOI: 10.3168/jds.2016-10890] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 07/15/2016] [Indexed: 11/19/2022]
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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; 98:3371-88. [PMID: 24493567 DOI: 10.1007/s00253-013-5466-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 12/11/2013] [Accepted: 12/11/2013] [Indexed: 12/29/2022]
Abstract
The denitrifying betaproteobacterium "Aromatoleum aromaticum" EbN1 is a well-studied model organism for anaerobic degradation of aromatic compounds. Following publication of its genome in 2005, comprehensive physiological-proteomic studies were conducted to deduce functional understanding from the genomic blueprint. A catabolic network (85 predicted, 65 identified proteins) for anaerobic degradation of 24 aromatic growth substrates (including 11 newly recognized) was established. Newly elucidated pathways include those for 4-ethylphenol and plant-derived 3-phenylpropanoids, involving functional assignment of several paralogous genes. The substrate-specific regulation of individual peripheral degradation pathways is probably initiated by highly specific chemical sensing via dedicated sensory/regulatory proteins, e.g. three different σ⁵⁴-dependent one-component sensory/regulatory proteins are predicted to discriminate between three phenolic substrates (phenol, p-cresol and 4-ethylphenol) and two different two-component systems are assumed to differentiate between two alkylbenzenes (toluene, ethylbenzene). Investigations under in situ relevant growth conditions revealed (a) preferred utilization of benzoate from a mixture with succinate results from repressed synthesis of a C₄-dicarboxylate TRAP transporter; (b) response to alkylbenzene-induced solvent stress comprises metabolic re-routing of acetyl-CoA and reducing equivalents to poly(3-hydroxybutyrate) synthesis, alteration of cellular membrane composition and formation of putative solvent efflux systems; and (c) multifaceted adaptation to slow growth includes adjustment of energy demand for maintenance and preparedness for future nutritional opportunities, i.e. provision of uptake systems and catabolic enzymes for multiple aromatic substrates despite their absence. This broad knowledge base taken together with the recent development of a genetic system will facilitate future functional, biotechnological (stereospecific dehydrogenases) and habitat re-enacting ("eco-"systems biology) studies with "A. aromaticum" EbN1.
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Affiliation(s)
- Ralf Rabus
- Institut für Chemie und Biologie des Meeres (ICBM), AG Allgemeine und Molekulare Mikrobiologie, Carl von Ossietzky Universität Oldenburg, Carl-von-Ossietzky Str. 9-11, 26111, Oldenburg, Germany,
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8
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Limam I, Mezni M, Guenne A, Madigou C, Driss MR, Bouchez T, Mazéas L. Evaluation of biodegradability of phenol and bisphenol A during mesophilic and thermophilic municipal solid waste anaerobic digestion using 13C-labeled contaminants. CHEMOSPHERE 2013; 90:512-20. [PMID: 22985591 DOI: 10.1016/j.chemosphere.2012.08.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 08/02/2012] [Accepted: 08/08/2012] [Indexed: 05/24/2023]
Abstract
In this paper, the isotopic tracing using (13)C-labeled phenol and bisphenol A was used to study their biodegradation during anaerobic digestion of municipal solid waste. Microcosms were incubated anaerobically at 35 °C (mesophilic conditions) and 55 °C (thermophilic conditions) without steering. A continuous follow-up of the production of biogas (CH(4) and CO(2)), was carried out during 130 d until the establishment of stable methanogenesis. Then (13)C(12)-BPA, and (13)C(6)-phenol were injected in microcosms and the follow-up of their degradation was performed simultaneously by gas chromatography isotope-ratio mass spectrometry (GC-IRMS) and gas chromatography mass spectrometry (GC-MS). Moreover, Carbon-13 Nuclear Magnetic Resonance ((13)C-NMR) Spectroscopy is used in the identification of metabolites. This study proves that the mineralization of phenol to CO(2) and CH(4) occurs during anaerobic digestion both in mesophilic and thermophilic conditions with similar kinetics. In mesophilic condition phenol degradation occurs through the benzoic acid pathway. In thermophilic condition it was not possible to identify the complete metabolic pathway as only acetate was identified as metabolite. Our results suggest that mineralization of phenol under thermophilic condition is instantaneous explaining why metabolites are not observed as they do not accumulate. No biodegradation of BPA was observed.
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Affiliation(s)
- Intissar Limam
- Hydrosystems and Bioprocesses Research Unit, IRSTEA, 1 rue Pierre-Gilles de Gennes, CS 10030, F-92761 Antony Cedex, France.
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Epoxy Coenzyme A Thioester pathways for degradation of aromatic compounds. Appl Environ Microbiol 2012; 78:5043-51. [PMID: 22582071 DOI: 10.1128/aem.00633-12] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aromatic compounds (biogenic and anthropogenic) are abundant in the biosphere. Some of them are well-known environmental pollutants. Although the aromatic nucleus is relatively recalcitrant, microorganisms have developed various catabolic routes that enable complete biodegradation of aromatic compounds. The adopted degradation pathways depend on the availability of oxygen. Under oxic conditions, microorganisms utilize oxygen as a cosubstrate to activate and cleave the aromatic ring. In contrast, under anoxic conditions, the aromatic compounds are transformed to coenzyme A (CoA) thioesters followed by energy-consuming reduction of the ring. Eventually, the dearomatized ring is opened via a hydrolytic mechanism. Recently, novel catabolic pathways for the aerobic degradation of aromatic compounds were elucidated that differ significantly from the established catabolic routes. The new pathways were investigated in detail for the aerobic bacterial degradation of benzoate and phenylacetate. In both cases, the pathway is initiated by transforming the substrate to a CoA thioester and all the intermediates are bound by CoA. The subsequent reactions involve epoxidation of the aromatic ring followed by hydrolytic ring cleavage. Here we discuss the novel pathways, with a particular focus on their unique features and occurrence as well as ecological significance.
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Bains J, Leon R, Temke KG, Boulanger MJ. Elucidating the reaction mechanism of the benzoate oxidation pathway encoded aldehyde dehydrogenase from Burkholderia xenovorans LB400. Protein Sci 2011; 20:1048-59. [PMID: 21495107 DOI: 10.1002/pro.639] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 04/04/2011] [Accepted: 04/07/2011] [Indexed: 11/09/2022]
Abstract
Oxidation of cis-3,4-dehydroadipyl-CoA semialdehyde to cis-3,4-dehydroadipyl-CoA by the aldehyde dehydrogenase, ALDH(C) (EC.1.2.1.77), is an essential step in the metabolism of benzoate in Burkholderia xenovorans LB400. In a previous study, we established a structural blueprint for this novel group of ALDH enzymes. Here, we build significantly on this initial work and propose a detailed reaction mechanism for ALDH(C) based on comprehensive structural and functional investigations of active site residues. Kinetic analyses reveal essential roles for C296 as the nucleophile and E257 as the associated general base. Structural analyses of E257Q and C296A variants suggest a dynamic charge repulsion relationship between E257 and C296 that contributes to the inherent flexibility of E257 in the native enzyme, which is further regulated by E496 and E167. A proton relay network anchored by E496 and supported by E167 and K168 serves to reset E257 for the second catalytic step. We also propose that E167, which is unique to ALDH(C) and its homologs, serves a critical role in presenting the catalytic water to the newly reset E257 such that the enzyme can proceed with deacylation and product release. Collectively, the reaction mechanism proposed for ALDH(C) promotes a greater understanding of these novel ALDH enzymes, the ALDH super-family in general, and benzoate degradation in B. xenovorans LB400.
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Affiliation(s)
- Jasleen Bains
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W3P6, Canada
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11
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Patel TR, Jure KG, Jones GA. Catabolism of phloroglucinol by the rumen anaerobe coprococcus. Appl Environ Microbiol 2010; 42:1010-7. [PMID: 16345897 PMCID: PMC244147 DOI: 10.1128/aem.42.6.1010-1017.1981] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A rumen isolate, Coprococcus, sp. Pe(1)5, was found to carry phloroglucinol reductase, which catalyzed the initial step in the breakdown of phloroglucinol. The organism uses phloroglucinol as the sole source of carbon and energy when grown in the absence of oxygen. Induced levels of enzyme were detected in cells grown either on phloroglucinol or on other carbon sources in the presence of limiting quantities of phloroglucinol. Although the organism is a strict anaerobe, the enzyme from anaerobically grown cells was insensitive to air. The partially purified enzyme required reduced nicotinamide adenine dinucleotide phosphate as an electron donor and was specific for phloroglucinol. However, partial enzyme activity (14 to 17%) was also detected in the presence of 2-methyl-1,4-naphthoquinone but not in the presence of several other phenolic compounds. The enzyme exhibited a higher affinity for phloroglucinol than for reduced nicotinamide adenine dinucleotide phosphate, with K(m) values of 3.0 x 10 M and 29.0 x 10 M, respectively. The optimum pH for maximal enzyme activity was 7.4, and the molecular weight of the native protein was about 130,000, as determined by the Sephadex gel filtration technique.
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Affiliation(s)
- T R Patel
- Department of Dairy and Food Science, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 0W0
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12
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Horowitz A, Suflita JM, Tiedje JM. Reductive dehalogenations of halobenzoates by anaerobic lake sediment microorganisms. Appl Environ Microbiol 2010; 45:1459-65. [PMID: 16346284 PMCID: PMC242485 DOI: 10.1128/aem.45.5.1459-1465.1983] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Methane-producing freshwater lake sediment was found to dehalogenate chloro-, bromo-, and iodobenzoates by a reductive reaction in which the halogen was replaced by a hydrogen atom. The identity of the dehalogenated products was confirmed by mass spectrometry, nuclear magnetic resonance, or cochromatography. Removal of the halogens to produce benzoate was necessary before mineralization to CH(4) + CO(2) could occur. The dehalogenation occurred after a lag period which lasted from 1 week to more than 6 months, depending on the chemical. Dehalogenation was not observed in the absence of CH(4) production, and it was inhibited by the addition of 20% O(2). Once sediment was acclimated to halobenzoate dehalogenation, new additions of the halobenzoate were degraded without lag. Acclimation was observed regardless of whether the parent substrates were eventually mineralized to CH(4) + CO(2). Sediment acclimated to bromo- and chlorobenzoate degradation generally metabolized bromo- and chlorobenzoates, but sediment acclimated to iodobenzoate degradation only metabolized iodobenzoate. Prior acclimation of sediment to benzoate decomposition did not alter the pattern of dehalogenation, and sediment acclimated to dehalogenation was not concurrently acclimated to benzoate degradation. The presence of this apparent specificity, the lag period, and subsequent acclimation, together with our findings of the absence of dehalogenation in sterile sediments and by sediments previously incubated at >/=39 degrees C, suggests that this reaction was biologically catalyzed. Apparently, a pathway for the reductive dehalogenation of aryl halides is present in anaerobic microorganisms of this methanogenic sediment.
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Affiliation(s)
- A Horowitz
- Departments of Crop and Soil Sciences and of Microbiology and Public Health, Michigan State University, East Lansing, Michigan 48824
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13
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Abstract
The decarboxylation of phthalic acids was studied with Bacillus sp. strain FO, a marine mixed culture ON-7, and Pseudomonas testosteroni. The mixed culture ON-7, when grown anaerobically on phthalate but incubated aerobically with chloramphenicol, quantitatively converted phthalic acid to benzoic acid. Substituted phthalic acids were also decarboxylated: 4,5-dihydroxyphthalic acid to protocatechuic acid; 4-hydroxyphthalic and 4-chlorophthalic acids to 3-hydroxybenzoic and 3-chlorobenzoic acids, respectively; and 3-fluorophthalic acid to 2-and 3-fluorobenzoic acids. Bacillus sp. strain FO gave similar results except that 4,5-dihydroxyphthalic acid was not metabolized, and both 3- and 4-hydroxybenzoic acids were produced from 4-hydroxyphthalic acid. P. testosteroni decarboxylated 4-hydroxyphthalate (to 3-hydroxybenzoate) and 4,5-dihydroxyphthalate but not phthalic acid and halogenated phthalates. Thus, P. testosteroni and the mixed culture ON-7 possessed 4,5-dihydroxyphthalic acid decarboxylase, previously described in P. testosteroni, that metabolized 4,5-dihydroxyphthalic acid and specifically decarboxylated 4-hydroxyphthalic acid to 3-hydroxybenzoic acid. The mixed culture ON-7 and Bacillus sp. strain FO also possessed a novel decarboxylase that metabolized phthalic acid and halogenated phthalates, but not 4,5-dihydroxyphthalate, and randomly decarboxylated 4-hydroxyphthalic acid. The decarboxylation of phthalic acid is suggested to involve an initial reduction to 1,2-dihydrophthalic acid followed by oxidative decarboxylation to benzoic acid.
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Affiliation(s)
- B F Taylor
- Division of Marine and Atmospheric Chemistry, Rosenstiel School of Marine and Atmospheric Science, and Department of Biochemistry, School of Medicine, University of Miami, Miami, Florida 33149-1098
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Haritash AK, Kaushik CP. Biodegradation aspects of polycyclic aromatic hydrocarbons (PAHs): a review. JOURNAL OF HAZARDOUS MATERIALS 2009; 169:1-15. [PMID: 19442441 DOI: 10.1016/j.jhazmat.2009.03.137] [Citation(s) in RCA: 1440] [Impact Index Per Article: 96.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2009] [Revised: 03/30/2009] [Accepted: 03/30/2009] [Indexed: 05/24/2023]
Abstract
PAHs are aromatic hydrocarbons with two or more fused benzene rings with natural as well as anthropogenic sources. They are widely distributed environmental contaminants that have detrimental biological effects, toxicity, mutagenecity and carcinogenicity. Due to their ubiquitous occurrence, recalcitrance, bioaccumulation potential and carcinogenic activity, the PAHs have gathered significant environmental concern. Although PAH may undergo adsorption, volatilization, photolysis, and chemical degradation, microbial degradation is the major degradation process. PAH degradation depends on the environmental conditions, number and type of the microorganisms, nature and chemical structure of the chemical compound being degraded. They are biodegraded/biotransformed into less complex metabolites, and through mineralization into inorganic minerals, H(2)O, CO(2) (aerobic) or CH(4) (anaerobic) and rate of biodegradation depends on pH, temperature, oxygen, microbial population, degree of acclimation, accessibility of nutrients, chemical structure of the compound, cellular transport properties, and chemical partitioning in growth medium. A number of bacterial species are known to degrade PAHs and most of them are isolated from contaminated soil or sediments. Pseudomonas aeruginosa, Pseudomons fluoresens, Mycobacterium spp., Haemophilus spp., Rhodococcus spp., Paenibacillus spp. are some of the commonly studied PAH-degrading bacteria. Lignolytic fungi too have the property of PAH degradation. Phanerochaete chrysosporium, Bjerkandera adusta, and Pleurotus ostreatus are the common PAH-degrading fungi. Enzymes involved in the degradation of PAHs are oxygenase, dehydrogenase and lignolytic enzymes. Fungal lignolytic enzymes are lignin peroxidase, laccase, and manganese peroxidase. They are extracellular and catalyze radical formation by oxidation to destabilize bonds in a molecule. The biodegradation of PAHs has been observed under both aerobic and anaerobic conditions and the rate can be enhanced by physical/chemical pretreatment of contaminated soil. Addition of biosurfactant-producing bacteria and light oils can increase the bioavailability of PAHs and metabolic potential of the bacterial community. The supplementation of contaminated soils with compost materials can also enhance biodegradation without long-term accumulation of extractable polar and more available intermediates. Wetlands, too, have found an application in PAH removal from wastewater. The intensive biological activities in such an ecosystem lead to a high rate of autotrophic and heterotrophic processes. Aquatic weeds Typha spp. and Scirpus lacustris have been used in horizontal-vertical macrophyte based wetlands to treat PAHs. An integrated approach of physical, chemical, and biological degradation may be adopted to get synergistically enhanced removal rates and to treat/remediate the contaminated sites in an ecologically favorable process.
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Affiliation(s)
- A K Haritash
- Department of Environmental Science & Engineering, Guru Jambheshwar University of Science & Technology, Hisar, Haryana, India.
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Bains J, Leon R, Boulanger MJ. Structural and biophysical characterization of BoxC from Burkholderia xenovorans LB400: a novel ring-cleaving enzyme in the crotonase superfamily. J Biol Chem 2009; 284:16377-16385. [PMID: 19369256 DOI: 10.1074/jbc.m900226200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mineralization of aromatic compounds by microorganisms relies on a structurally and functionally diverse group of ring-cleaving enzymes. The recently discovered benzoate oxidation pathway in Burkholderia xenovorans LB400 encodes a novel such ring-cleaving enzyme, termed BoxC, that catalyzes the conversion of 2,3-dihydro-2,3-dihydroxybenzoyl-CoA to 3,4-dehydroadipyl-CoA without the requirement for molecular oxygen. Sequence analysis indicates that BoxC is a highly divergent member of the crotonase superfamily and nearly double the size of the average superfamily member. The structure of BoxC determined to 1.5 A resolution reveals an intriguing structural demarcation. A highly divergent region in the C terminus probably serves as a structural scaffold for the conserved N terminus that encompasses the active site and, in conjunction with a conserved C-terminal helix, mediates dimer formation. Isothermal titration calorimetry and molecular docking simulations contribute to a detailed view of the active site, resulting in a compelling mechanistic model where a pair of conserved glutamate residues (Glu146 and Glu168) work in tandem to deprotonate the dihydroxylated ring substrate, leading to cleavage. A final deformylation step incorporating a water molecule and Cys111 as a general base completes the formation of 3,4-dehydroadipyl-CoA product. Overall, this study establishes the basis for BoxC as one of the most divergent members of the crotonase superfamily and provides the first structural insight into the mechanism of this novel class of ring-cleaving enzymes.
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Affiliation(s)
- Jasleen Bains
- From the Departments of Biochemistry and Microbiology, Victoria, British Columbia V8W 3P6, Canada
| | - Rafael Leon
- Chemistry, University of Victoria, Victoria, British Columbia V8W 3P6, Canada
| | - Martin J Boulanger
- From the Departments of Biochemistry and Microbiology, Victoria, British Columbia V8W 3P6, Canada.
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Mouttaki H, Nanny MA, McInerney MJ. Metabolism of hydroxylated and fluorinated benzoates by Syntrophus aciditrophicus and detection of a fluorodiene metabolite. Appl Environ Microbiol 2009; 75:998-1004. [PMID: 19114508 PMCID: PMC2643595 DOI: 10.1128/aem.01870-08] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 12/18/2008] [Indexed: 11/20/2022] Open
Abstract
Transformations of 2-hydroxybenzoate and fluorobenzoate isomers were investigated in the strictly anaerobic Syntrophus aciditrophicus to gain insight into the initial steps of the metabolism of aromatic acids. 2-Hydroxybenzoate was metabolized to methane and acetate by S. aciditrophicus and Methanospirillum hungatei cocultures and reduced to cyclohexane carboxylate by pure cultures of S. aciditrophicus when grown in the presence of crotonate. Under both conditions, transient accumulation of benzoate but not phenol was observed, indicating that dehydroxylation occurred prior to ring reduction. Pure cultures of S. aciditrophicus reductively dehalogenated 3-fluorobenzoate with the stoichiometric accumulation of benzoate and fluorine. 3-Fluorobenzoate-degrading cultures produced a metabolite that had a fragmentation pattern almost identical to that of the trimethylsilyl (TMS) derivative of 3-fluorobenzoate but with a mass increase of 2 units. When cells were incubated with deuterated water, this metabolite had a mass increase of 3 or 4 units relative to the TMS derivative of 3-fluorobenzoate. (19)F nuclear magnetic resonance spectroscopy ((19)F NMR) detected a metabolite in fluorobenzoate-degrading cultures with two double bonds, either 1-carboxyl-3-fluoro-2,6-cyclohexadiene or 1-carboxyl-3-fluoro-3,6-cyclohexadiene. The mass spectral and NMR data are consistent with the addition of two hydrogen or deuterium atoms to 3-fluorobenzoate, forming a 3-fluorocyclohexadiene metabolite. The production of a diene metabolite provides evidence that S. aciditrophicus contains dearomatizing reductase that uses two electrons to dearomatize the aromatic ring.
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Affiliation(s)
- Housna Mouttaki
- Department of Botany and Microbiology, University of Oklahoma, 770 Van Vleet Oval, Norman, OK 73019, USA.
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Brown MJ, Moses V, Robinson JP, Springham DG, Bubela B. Microbial Enhanced Oil Recovery: Progress and Prospects. Crit Rev Biotechnol 2008. [DOI: 10.3109/07388558509150783] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Mouttaki H, Nanny MA, McInerney MJ. Use of benzoate as an electron acceptor by Syntrophus aciditrophicus grown in pure culture with crotonate. Environ Microbiol 2008; 10:3265-74. [PMID: 18707608 DOI: 10.1111/j.1462-2920.2008.01716.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In methanogenic environments, the main fate of benzoate is its oxidization to acetate, H(2) and CO(2) by syntrophic associations of hydrogen-producing benzoate degraders and hydrogen-using methanogens. Here, we report the use of benzoate as an electron acceptor. Pure cultures of S. aciditrophicus simultaneously degraded crotonate and benzoate when both substrates were present. The growth rate was 0.007 h(-1) with crotonate and benzoate present compared with 0.025 h(-1) with crotonate alone. After 8 days of incubation, 4.12 +/- 0.50 mM of cyclohexane carboxylate and 8.40 +/- 0.61 mM of acetate were formed and 4.0 +/- 0.04 mM of benzoate and 4.8 +/- 0.5 mM of crotonate were consumed. The molar growth yield was 22.7 +/- 2.1 g (dry wt) of cells per mol of crotonate compared with about 14.0 +/- 0.1 g (dry wt) of cells per mol of crotonate when S. aciditrophicus was grown with crotonate alone. Cultures grown with [ring-(13)C]-benzoate and unlabelled crotonate initially formed [ring-(13)C]-labelled cyclohexane carboxylate. No (13)C-labelled acetate was detected. In addition to cyclohexane carboxylate, (13)C-labelled cyclohex-1-ene carboxylate was detected as an intermediate. Once almost all of the benzoate was gone, carbon isotopic analyses showed that cyclohexane carboxylate was formed from both labelled and non-labelled metabolites. Glutarate and pimelate were also detected at this time and carbon isotopic analyses showed that each was made from a mixture labelled and non-labelled metabolites. The increase in molar growth yield with crotonate and benzoate and the formation of [ring-(13)C]-cyclohexane carboxylate from [ring-(13)C]-benzoate in the presence of crotonate are consistent with benzoate serving as an electron acceptor.
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Affiliation(s)
- Housna Mouttaki
- Departments of Botany and Microbiology, University of Oklahoma, Norman, OK, USA
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Abstract
Aromatic compounds comprise a wide variety of natural and synthetic compounds that can serve as substrates for bacterial growth. So far, four types of aromatic metabolism are known. (1) The aerobic aromatic metabolism is characterized by the extensive use of molecular oxygen as cosubstrate for oxygenases that introduce hydroxyl groups and cleave the aromatic ring. (2) In the presence of oxygen, facultative aerobes use another so-called hybrid type of aerobic metabolism of benzoate, phenylacetate, and anthranilate (2-aminobenzoate). These pathways use coenzyme A thioesters of the substrates and do not require oxygen for ring cleavage; rather they use an oxygenase/reductase to dearomatize the ring. (3) In the absence of oxygen, facultative aerobes and phototrophs use a reductive aromatic metabolism. Reduction of the aromatic ring of benzoyl-coenzyme A is catalyzed by benzoyl-coenzyme A reductase. This Birch-like reduction is driven by the hydrolysis of 2 ATP molecules. (4) A completely different, still little characterized benzoyl-coenzyme A reductase operates in strict anaerobes, which cannot afford the costly ATP-dependent ring reduction.
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Affiliation(s)
- Georg Fuchs
- Microbiology, Faculty of Biology, University of Freiburg, Schaenzelstr. 1, D-79104 Freiburg, Germany.
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Chen CL, Wu JH, Liu WT. Identification of important microbial populations in the mesophilic and thermophilic phenol-degrading methanogenic consortia. WATER RESEARCH 2008; 42:1963-76. [PMID: 18234274 DOI: 10.1016/j.watres.2007.11.037] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Revised: 11/22/2007] [Accepted: 11/24/2007] [Indexed: 05/23/2023]
Abstract
Active mesophilic and thermophilic phenol-degrading methanogenic consortia were obtained after an 18-month acclimation and enriching process in the serum bottles, and characterized using the rRNA-based molecular approach. As revealed by cloning, fluorescence in situ hybridization (FISH) and terminal restriction fragment length polymorphism (T-RFLP), these two enrichments differed greatly in the community structures. The results for the first time suggest that group TA in the Deltaproteobacteria (88.0% of EUBmix FISH-detectable bacterial cell area) and Pelotomaculum spp. in the Desulfotomaculum family (81.2%) were the predominant fermentative bacteria under mesophilic (37 degrees C) and thermophilic (55 degrees C) conditions, respectively. These populations closely associated with mesophilic and thermophilic members of Methanosaetaceae, Methanobacteriaceae and Methanomicrobiales to mineralize phenol as the sole carbon substrate to carbon dioxide and methane. Moreover, these two enrichments could mineralize terephthalate and benzoate. During benzoate degradation in the mesophilic enrichment, a shift in the predominant bacterial population from Deltaproteobacteria group TA to Syntrophus spp. was observed, suggesting Syntrophus-related spp. could have a higher substrate affinity for benzoate. FISH further revealed that member of the Deltaproteobacteria group TA represented more than 68.3% of EUBmix FISH-detectable bacterial cell area in a full-scale mesophilic bioreactor treating phenol-containing wastewaters.
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Affiliation(s)
- Chia-Lung Chen
- Department of Civil Engineering, National University of Singapore, Singapore
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Heider J, Fuchs G. Microbial anaerobic aromatic metabolism. Anaerobe 2007; 3:1-22. [PMID: 16887557 DOI: 10.1006/anae.1997.0073] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/1997] [Accepted: 02/11/1997] [Indexed: 11/22/2022]
Affiliation(s)
- J Heider
- Mikrobiologie, Institut für Biologie II, Universität Freiburg, Freiburg, Germany.
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Karlsson A, Ejlertsson J, Nezirevic D, Svensson BH. Degradation of phenol under meso- and thermophilic, anaerobic conditions. Anaerobe 2007; 5:25-35. [PMID: 16887659 DOI: 10.1006/anae.1998.0187] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/1998] [Accepted: 12/31/1998] [Indexed: 11/22/2022]
Abstract
Based on the results of preliminary studies on phenol degradation under mesophilic conditions with a mixed methanogenic culture, we proposed a degradation pathway in which phenol is fermented to acetate: Part of the phenol is reductively transformed to benzoate while the rest is oxidised, forming acetate as end product. According to our calculations, this should result in three moles of phenol being converted to two moles of benzoate and three moles of acetate (3 phenol + 2 CO2 + 3 H2O --> 3 acetate + 2 benzoate): To assess the validity of our hypothesis concerning the metabolic pathway, we studied the transformation of phenol under mesophilic and thermophilic conditions in relation to the availability of hydrogen. Hence, methanogenic meso- and thermophilic cultures amended with phenol were run with or without an added over-pressure of hydrogen under methanogenic and non-methanogenic conditions. Bromoethanesulfonic acid (BES) was used to inhibit methanogenic activity. In the mesophilic treatments amended with only BES, about 70% of the carbon in the products found was benzoate. During the course of phenol transformation in these BES-amended cultures, the formation pattern of the degradation products changed: Initially nearly 90% of the carbon from phenol degradation was recovered as benzoate, whereas later in the incubation, in addition to benzoate formation, the aromatic nucleus degraded completely to acetate. Thus, the initial reduction of phenol to benzoate resulted in a lowering of H2 levels, giving rise to conditions allowing the degradation of phenol to acetate as the end product. Product formation in bottles amended with BES and phenol occurred in accordance with the hypothesised pathway; however, the overall results indicate that the degradation of phenol in this system is more complex. During phenol transformation under thermophilic conditions, no benzoate was observed and no phenol was transformed in the BES-amended cultures. This suggests that the sensitivity of phenol transformation to an elevated partial pressure of H2 is higher under thermophilic conditions than under mesophilic ones. The lack of benzoate formation could have been due to a high turnover of benzoate or to a difference in the phenol degradation pathway between the thermophilic and mesophilic cultures.
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Affiliation(s)
- A Karlsson
- Department of Water and Environmental Studies, University of Linköping, S-581 83, Linköping, Sweden.
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Ramakrishnan A, Gupta SK. Anaerobic biogranulation in a hybrid reactor treating phenolic waste. JOURNAL OF HAZARDOUS MATERIALS 2006; 137:1488-95. [PMID: 16762495 DOI: 10.1016/j.jhazmat.2006.04.034] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2005] [Revised: 04/17/2006] [Accepted: 04/18/2006] [Indexed: 05/10/2023]
Abstract
Granulation was examined in four similar anaerobic hybrid reactors 15.5L volume (with an effective volume of 13.5L) during the treatment of synthetic coal wastewater at the mesophilic temperature of 27+/-5 degrees C. The hybrid reactors are a combination of UASB unit at the lower part and an anaerobic filter at the upper end. Synthetic wastewater with an average chemical oxygen demand (COD) of 2,240 mg/L, phenolics concentration of 752 mg/L and a mixture of volatile fatty acids was fed to three hybrid reactors. The fourth reactor, control system, was fed with a wastewater containing sodium acetate and mineral nutrients. Coal waste water contained phenol (490 mg/L); m-, o-, p-cresols (123.0, 58.6, 42 mg/L); 2,4-, 2,5-, 3,4- and 3,5-dimethyl phenols (6.3, 6.3, 4.4 and 21.3mg/L) as major phenolic compounds. A mixture of anaerobic digester sludge and partially granulated sludge (3:1) were used as seed materials for the start up of the reactors. Granules were observed after 45 days of operation of the systems. The granules ranged from 0.4 to 1.2 mm in diameter with good settling characteristics with an SVI of 12 mL/gSS. After granulation, the hybrid reactor performed steadily with phenolics and COD removal efficiencies of 93% and 88%, respectively at volumetric loading rate of 2.24 g COD/Ld and hydraulic retention time of 24 h. The removal efficiencies for phenol and m/p-cresols reached 92% and 93% (corresponding to 450.8 and 153 mg/L), while o-cresol was degraded to 88% (corresponding to 51.04 mg/L). Dimethyl phenols could be removed completely at all the organic loadings and did not contribute much to the residual organics. Biodegradation of o-cresol was obtained in the hybrid-UASB reactors.
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Affiliation(s)
- Anushyaa Ramakrishnan
- Centre for Environmental Science and Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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Levén L, Nyberg K, Korkea-Aho L, Schnürer A. Phenols in anaerobic digestion processes and inhibition of ammonia oxidising bacteria (AOB) in soil. THE SCIENCE OF THE TOTAL ENVIRONMENT 2006; 364:229-38. [PMID: 16125214 DOI: 10.1016/j.scitotenv.2005.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2004] [Accepted: 06/06/2005] [Indexed: 05/04/2023]
Abstract
This study focuses on the presence of phenols in digestate from seven Swedish large-scale anaerobic digestion processes and their impact on the activity of ammonia oxidising bacteria (AOB) in soil. In addition, the importance of feedstock composition and phenol degradation capacity for the occurrence of phenols in the digestate was investigated in the same processes. The results revealed that the content of phenols in the digestate was related to the inhibition of the activity of AOB in soil (EC(50)=26 microg phenols g(-1) d.w. soil). In addition, five pure phenols (phenol, o-, p-, m-cresol and 4-ethylphenol) inhibited the AOB to a similar extent (EC(50)=43-110 microg g(-1) d.w. soil). The phenol content in the digestate was mainly dependent on the composition of the feedstock, but also to some extent by the degradation capacity in the anaerobic digestion process. Swine manure in the feedstock resulted in digestate containing higher amounts of phenols than digestate from reactors with less or no swine manure in the feedstock. The degradation capacity of phenol and p-cresol was studied in diluted small-scale batch cultures and revealed that anaerobic digestion at mesophilic temperatures generally exhibited a higher degradation capacity compared to digestion at thermophilic temperature. Although phenol, p-cresol and 4-ethylphenol were quickly degraded in soil, the phenols added with the digestate constitute an environmental risk according to the guideline values for contaminated soils set by the Swedish Environmental Protection Agency. In conclusion, the management of anaerobic digestion processes is of decisive importance for the production of digestate with low amounts of phenols, and thereby little risks for negative effects of the phenols on the soil ecosystem.
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Affiliation(s)
- Lotta Levén
- Department of Microbiology, Swedish University of Agricultural Sciences, Box 7025, SE-750 07 Uppsala, Sweden.
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Zhao PJ, Fan LM, Li GH, Zhu N, Shen YM. Antibacterial and antitumor macrolides fromstreptomyces sp. Is9131. Arch Pharm Res 2005; 28:1228-32. [PMID: 16350846 DOI: 10.1007/bf02978203] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Four compounds, including two novel macrolides, were isolated from an endophyte Streptomyces sp. Is9131 of Maytenus hookeri. Spectral data indicated that these compounds were dimeric dinactin (1), dimeric nonactin (2), cyclo-homononactic acid (3), and cyclo-nonactic acid (4). Bioassay results showed that dimeric dinactin had strong antineoplastic activity and antibacterial activity.
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Affiliation(s)
- Pei-Ji Zhao
- The State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Science, Kunming 650204, China
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Kube M, Beck A, Meyerdierks A, Amann R, Reinhardt R, Rabus R. A catabolic gene cluster for anaerobic benzoate degradation in methanotrophic microbial Black Sea mats. Syst Appl Microbiol 2005; 28:287-94. [PMID: 15997700 DOI: 10.1016/j.syapm.2005.02.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A microbial mat from the Black Sea shelf was analyzed by a metagenomic approach. While the habitat and its microbial community are characterized by anaerobic methane oxidation, a 79 kb contiguous DNA sequence obtained from the same mat provided first evidence for the concomitant presence of the capacity for anaerobic benzoate degradation. Benzoyl-CoA is one central intermediate of anaerobic aromatic degradation, among others. Within a stretch of 31 kb, all genes required for the complete pathway of anaerobic benzoate degradation (catabolic island) were identified, including the four subunits of the key enzyme benzoyl-CoA reductase (bcrCBAD), which catalyzes the ATP-driven 2-electron reduction of the aromatic ring. Genes for a ketoacid:acceptor oxidoreductase (korABC) and a ferredoxin (fdx), which are required for generation of a suitable electron donor, were also detected. The majority of the identified catabolic gene products are most similar to their respective orthologs from the denitrifying freshwater bacterium Azoarcus evansii, and the genes are also similarly organized. Due to the lack of established markers, the phylogenetic affiliation of the source organism remains unclear. The presented findings indicate that the metabolic diversity of the Black Sea mat is wider than currently known and that probably other bacteria than those of the methane-oxidizing consortia contribute to aromatic degradation in this anoxic habitat.
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Affiliation(s)
- Michael Kube
- Max Planck Institut fir Molekulare Genetik, Ihnestr. 73, D-14129 Berlin, Germany
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Yan H, Pan G. Increase in biodegradation of dimethyl phthalate by Closterium lunula using inorganic carbon. CHEMOSPHERE 2004; 55:1281-1285. [PMID: 15081769 DOI: 10.1016/j.chemosphere.2003.12.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2003] [Revised: 09/11/2003] [Accepted: 12/31/2003] [Indexed: 05/24/2023]
Abstract
The effect and mechanism of inorganic carbon (IC) on the biodegradation of dimethyl phthalate (DMP) by a green microalga Closterium lunula was investigated. The growth of this microalga and the biodegradation of DMP were significantly enhanced when the initial IC was increased. An intermediate product of DMP biodegradation was identified as phthalic acid (PA) that was accumulated and caused a sharp decrease in pH of microalgal culture medium, which inhibited both the growth of microalga and the biodegradation of DMP. A suggested second-order kinetic equation of organic pollutant biodegradation by microalgae (-dC/dt = kNr) fitted well with the experimental data. The increase of IC caused a decline in biodegradation rate constant for organic carbon (k) and an increase in growth (N) by supplying a favorite carbon source and mitigating the decrease of pH. As the net effect, the overall biodegradation rate of DMP was promoted as IC increased, which was dominated by the increase of microalgal growth.
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Affiliation(s)
- Hai Yan
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, P.O. Box 18, Beijing 100085, China.
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Mechichi T, Stackebrandt E, Fuchs G. Alicycliphilus denitrificans gen. nov., sp. nov., a cyclohexanol-degrading, nitrate-reducing beta-proteobacterium. Int J Syst Evol Microbiol 2003; 53:147-152. [PMID: 12661531 DOI: 10.1099/ijs.0.02276-0] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A facultatively denitrifying bacterium, strain K601T, was isolated at 30 degrees C from a municipal sewage plant on cyclohexanol as sole carbon source and nitrate as electron acceptor. Under aerobic conditions this strain used acetate, fumarate, lactate, pyruvate, crotonate, indole, glucose, vanillate, 4-hydroxybenzoate, m-cresol, o-cresol and p-cresol. Under denitrifying conditions the strain used cyclohexanol, cyclohexanone, 1,3-cyclohexanedione, 2-cyclohexenone, 1,3-cyclohexanediol (cis and trans), monocarboxylic acids (C2-C7), adipate, pimelate, 5-oxocaproate, citrate, 2-oxoglutarate, succinate, malate, crotonate, lactate, pyruvate and fumarate. Cells were short rods, 0.6 microm wide and 1-2 microm long, motile, non-spore-forming, Gram-negative, and catalase- and oxidase-positive. Strain K601T used nitrate, nitrite and oxygen as electron acceptors, but not sulfate, sulfite or fumarate. The DNA G+C content of strain K601T was 66 mol%. Phylogenetic analysis, based on 16S rDNA sequencing, showed that strain K601T represents a separate lineage of the family Comamonadaceae in the beta-subclass of Proteobacteria. Based on the high 16S rDNA sequence divergence and phenotypic characteristics, the name Alicycliphilus denitrificans gen. nov., sp. nov. is proposed for this strain. The type strain is K60IT (=DSM 14773T =CIP 107495T).
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Affiliation(s)
- Tahar Mechichi
- Mikrobiologie, Institut für Biologie II, Universität Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany
| | - Erko Stackebrandt
- DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Braunschweig, Germany
| | - Georg Fuchs
- Mikrobiologie, Institut für Biologie II, Universität Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany
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Abstract
Aromatic compounds and hydrocarbons have in common a great stability due to resonance energy and inertness of CbondH and CbondC bonds. It has been taken for granted that the metabolism of these compounds obligatorily depends on molecular oxygen. Oxygen is required first to introduce hydroxyl groups into the substrate and then to cleave the aromatic ring. However, newly discovered bacterial enzymes and reactions involved in oxidation of aromatic and hydrocarbon compounds to CO(2) in the complete absence of molecular oxygen have been discovered. Of special interest are two reactions: the reduction of the aromatic ring of benzoyl-coenzyme A and the addition of fumarate to hydrocarbons. These reactions transform aromatic rings and hydrocarbons into products that can be oxidized via more conventional beta-oxidation pathways.
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Affiliation(s)
- Matthias Boll
- Institut für Biologie II, Mikrobiologie, Schänzlestr. 1, D-79104 Freiburg, Germany.
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Yan H, Pan G, Liang PL. Effect and mechanism of inorganic carbon on the biodegradation of dimethyl phthalate by Chlorella pyrenoidosa. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2002; 37:553-562. [PMID: 12046655 DOI: 10.1081/ese-120003236] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The effect and mechanism of inorganic carbon (IC) on the biodegradation of dimethyl phthalate (DMP) by a green microalga Chlorella pyrenoidosa was investigated. It was indicated that DMP could be used as the sole carbon source to support the slow heterotrophic growth of C. pyrenoidosa, but both the growth of C. pyrenoidosa and the biodegradation rate of DMP were obviously increased when initial inorganic carbon concentration (IC) was increased from 0.6 to 23.7 mg/l. Phthalic acid (PA) was found to be an intermediate product of DMP biodegradation and accumulated in the culture solution, which caused a sharp decrease in pH of medium and inhibited both the growth of alga and the biodegradation of DMP. The role of IC for improving the biodegradation of DMP was both to supply a favorite carbon source to support the rapid growth of alga and to mitigate the decrease of pH because of the production of PA. A suggested second-order kinetic equation of organic pollutant biodegradation by microalgae (-dC/dt = KNr) fitted well with the experimental data and the correlation coefficients were all above 0.9. The second-order constant (K) apparently declined with the increase of initial IC because lower ratio between organic carbon from DMP and IC was used to support the growth of alga when initial IC increased.
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Affiliation(s)
- Hai Yan
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing, PR China.
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Kajikawa H, Kudo H, Kondo T, Jodai K, Honda Y, Kuwahara M, Watanabe T. Degradation of benzyl ether bonds of lignin by ruminal microbes. FEMS Microbiol Lett 2000; 187:15-20. [PMID: 10828393 DOI: 10.1111/j.1574-6968.2000.tb09129.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
We examined microbial activity in the rumen to cleave benzyl ether bonds of lignin model compounds that fluoresced when the bonds were cleaved. 4-Methylumbelliferone veratryl ether dimer was degraded completely within 8 h even in the presence of fungicidal antibiotics, but no significant degradation occurred with bactericidal antibiotics. Degradation of a phenolic beta-O-4 trimer incorporating 4-methylumbelliferone by a benzyl ether linkage was stimulated by ruminal microbes, although its corresponding non-phenolic model compound, 1-(4-ethoxy-3-methoxyphenyl)-1-O-(4-methylumbelliferyl)-2-(2-methoxyp henoxy)-3-propanol, was not degraded. A coniferyl dehydrogenation polymer bearing fluorescent beta-O-4 benzyl ether that contains both phenolic and non-phenolic benzyl ether bonds was partially degraded (about 20%) in 48 h. These results suggest that ruminal microbes decompose benzyl ether linkages of lignin polymers under anaerobic conditions.
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Affiliation(s)
- H Kajikawa
- National Institute of Animal Industry, Tsukuba Norindanchi, Ibaraki, Japan
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35
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Harwood CS, Burchhardt G, Herrmann H, Fuchs G. Anaerobic metabolism of aromatic compounds via the benzoyl-CoA pathway. FEMS Microbiol Rev 1998. [DOI: 10.1111/j.1574-6976.1998.tb00380.x] [Citation(s) in RCA: 231] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Abstract
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 CO2 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. benzoyl-CoA) 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 P1 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-1,5-diene-1-carboxyl-CoA is oxidised to acetyl-CoA via a modified beta-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.
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Affiliation(s)
- J Heider
- Institut für Biologie II, Universităt Freiburg, Germany
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37
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The use of a classic lipid extraction method for simultaneous recovery of organic pollutants and microbial lipids from sediments. J Microbiol Methods 1996. [DOI: 10.1016/0167-7012(96)00929-3] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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38
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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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Küver J, Xu Y, Gibson J. Metabolism of cyclohexane carboxylic acid by the photosynthetic bacterium Rhodopseudomonas palustris. Arch Microbiol 1995; 164:337-45. [PMID: 8572887 DOI: 10.1007/bf02529980] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cyclohexane carboxylate supported relatively rapid growth (doubling times 7-8 h) of Rhodopseudomonas palustris under oxic or photosynthetic conditions, but did not serve as a substrate for either of the known aromatic CoA ligases. A CoA ligase that thioesterifies cyclohexane carboxylate was partially purified and did not cross react immunologically with the two CoA ligases purified previously from this bacterium. Crude extracts of R. palustris cells grown with a range of aromatic or alicyclic acids contained a dehydrogenase that reacted with cyclohexane carboxyl-CoA or cyclohex-1-ene carboxyl-CoA, using 2,6-dichlorophenolindophenol or ferricenium ion as electron carrier. This activity was not detected in extracts of adipate-, glutamate-, or succinate-grown cells. No oxidation or reduction of nonesterified cyclohexane carboxylate or cyclohexene carbocylate was detected in extracts of cells grown with aromatic or aliphatic substrates, neither aerobically nor anaerobically. A constitutively expressed thioesterase that hydrolyzed cyclohexane carboxyl-CoA and also some alicyclic and aliphatic CoA derivatives was purified and characterized. The enzyme had little or no activity on benzoyl-CoA or 4-hydroxybenzoyl-CoA. The presence of a thioesterase that effectively hydrolyzes cyclohexane carboxyl-CoA suggests that transient production of cyclohexane carboxylate is a physiological response to temporary excess of reductant during metabolism of aromatic compounds.
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Affiliation(s)
- J Küver
- Max-Planck-Institut für Marine Mikrobiologie, Bremen, Germany. jan@ postgate.mpi-mm.uni-bremen.de
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Villemur R. Coenzyme A ligases involved in anaerobic biodegradation of aromatic compounds. Can J Microbiol 1995; 41:855-61. [PMID: 8590400 DOI: 10.1139/m95-118] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Bacterial strains and consortia of bacteria have been isolated for their ability to degrade, under anaerobic conditions, homocyclic monoaromatic compounds, such as phenolic compounds, methylbenzenes, and aminobenzenes. As opposed to aerobic conditions where these compounds are degraded via dihydroxyl intermediates introduced by oxygenases, most of aromatic compounds under anaerobic conditions are metabolized via aromatic acid intermediates, such as nitrobenzoates, hydroxybenzoates, or phenylacetate. These aromatic acids are then transformed to benzoate before the reduction and the cleavage of the benzene ring to aliphatic acid products. One step of these catabolic pathways is the addition of a coenzyme A (CoA) residue to the carboxylic group of the aromatic acids by CoA ligases. This addition would facilitate the enzymatic transformation of the aromatic acids to benzoyl-CoA and the subsequent degradation steps of this latter molecule. Aromatic acid-CoA ligases have been characterized or detected from several bacterial strains that were grown under anaerobic conditions and from an anaerobic syntrophic consortium. They are also involved in the degradation of some aromatic compounds under aerobic conditions. They have molecular masses varying between 48 and 61 kDa, require ATP, Mg2+, and CoASH as cofactors, and have an optimum pH of 8.2-9.3. Amino acid sequence analyses of four aromatic acid-CoA ligases have revealed that they are related to an AMP-binding protein family. Aromatic acid-CoA ligases expressed in anaerobically grown bacterial cells are strictly regulated by the anaerobic conditions and the presence of aromatic cells.
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Affiliation(s)
- R Villemur
- Centre de recherche en microbiologie apliquée, Institut Armand-Frappier, Laval, Canada
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41
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Chang YJ, Nishio N, Nagai S. Characteristics of granular methanogenic sludge grown on phenol synthetic medium and methanogenic fermentation of phenolic wastewater in a UASB reactor. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/0922-338x(95)93993-t] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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42
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Besle JM, Jouany JP, Cornu A. Transformations of structural phenylpropanoids during cell wall digestion. FEMS Microbiol Rev 1995. [DOI: 10.1111/j.1574-6976.1995.tb00154.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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43
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Abstract
New obligately anaerobic bacteria are being discovered at an accelerating rate and it is becoming very evident that the diversity of anoxic biotransformations has been greatly underestimated. Furthermore, among contemporary anaerobes there are many that thrive in extreme environments including, for example, an impressive array of both archaebacterial and eubacterial hyperthermophiles. Free energy for growth and reproduction may be conserved not only via fermentations but also by anoxygenic photophosphorylation and other modes of creating transmembrane proton potential. Thus forms of anaerobic respiration in which various inorganic oxidants (or indeed carbon dioxide) serve as terminal electron acceptors have greatly extended the natural habitats in which such organisms may predominate. Anaerobic bacteria are, however, often found in nature as members of close microbial communities (consortia) that, although sustained by syntrophic and other relations between component species, are liable to alter their composition and character in response to environmental changes, e.g., availability of terminal oxidants. It follows that the biotechnological exploitation of obligately anaerobic bacteria must be informed by knowledge both of their biochemical capacities and of their normal environmental roles. It is against this background that illustrative examples of the activities of anaerobic bacteria are considered under three heads: 1. Biodegradation/Bioremediation, with special reference to the anaerobic breakdown of aromatic and/or halogenated organic substances; 2. Biosynthesis/Bioproduction, encompassing normal and modified fermentations; and 3. Biotransformations, accomplished by whole or semipermeabilized organisms or by enzymes derived therefrom, with particular interest attaching to the production of chiral compounds by a number of procedures, including electromicrobial reduction.
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Affiliation(s)
- J G Morris
- Institute of Biological Sciences, University of Wales, Penglais, Aberystwyth, UK
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44
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Elder DJ, Kelly DJ. The bacterial degradation of benzoic acid and benzenoid compounds under anaerobic conditions: unifying trends and new perspectives. FEMS Microbiol Rev 1994; 13:441-68. [PMID: 8011356 DOI: 10.1111/j.1574-6976.1994.tb00061.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Simple homocyclic aromatic compounds are extremely abundant in the environment and are derived largely from lignin. Such compounds may enter anaerobic environments and several groups of bacteria, exhibiting diverse energy-yielding mechanisms, have evolved the capacity to overcome the thermodynamic stability of the benzene nucleus and degrade aromatic compounds under these conditions. Over the last few years considerable advances have been made in our understanding of the biochemical strategies underlying the bacterial degradation of aromatic compounds in anoxic environments. The study of the biochemistry, and more recently the molecular genetics of the photosynthetic bacterium Rhodopseudomonas palustris and several strains of denitrifying pseudomonads, has provided the greatest insight into the mechanism and regulation of aromatic degradation under anaerobic conditions. Research has centred around the anaerobic degradation of benzoic acid. This involves the initial activation to form benzoyl-Coenzyme A, reduction of the aromatic nucleus--a reaction that has only recently been demonstrated in vitro--and the subsequent degradation of the alicyclic intermediates. Recently, much information regarding the exact nature of these intermediates has been obtained. Also through recent studies, it has become increasingly clear that benzoyl-CoA is a central metabolic intermediate during the anaerobic degradation of structurally diverse aromatic compounds. The initial metabolism of these compounds involves the formation of a carboxyl group on the aromatic nucleus (if necessary) and the synthesis of the respective Coenzyme A thioester; this results in the direct formation of benzoyl-Coenzyme A rather than benzoate. In many cases of anaerobic aromatic degradation studied in batch culture, aromatic intermediates are transiently excreted into the medium. It is argued that the study of this phenomenon may facilitate the understanding of the regulation and kinetics of the aromatic degradative pathways.
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Affiliation(s)
- D J Elder
- Department of Molecular Biology and Biotechnology, Universiyt of Sheffield, UK
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45
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Reichenbecher W, Brune A, Schink B. Transhydroxylase of Pelobacter acidigallici: a molybdoenzyme catalyzing the conversion of pyrogallol to phloroglucinol. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1204:217-24. [PMID: 8142462 DOI: 10.1016/0167-4838(94)90011-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Trihydroxybenzenes are degraded anaerobically through the phloroglucinol pathway. In Pelobacter acidigallici as well as in Pelobacter massiliensis, pyrogallol is converted to phloroglucinol in the presence of 1,2,3,5-tetrahydroxybenzene by intermolecular hydroxyl transfer. The enzyme catalyzing this reaction was purified to chromatographic and electrophoretic homogeneity. Gel filtration and electrophoresis revealed a heterodimer structure with an apparent molecular mass of 127 kDa for the native enzyme and 86 kDa and 38 kDa, respectively, for the subunits. The enzyme was not sensitive to oxygen. HgCl2, p-chloromercuribenzoic acid, and CuCl2 inhibited strongly the reaction indicating an essential function of SH-groups. Transhydroxylase had a pH-optimum of 7.0 and a pI of 4.1. The apparent temperature optimum was in the range of 53 degrees C to 58 degrees C. The activation energy for the conversion of pyrogallol and 1,2,3,5-tetrahydroxybenzene to phloroglucinol and tetrahydroxybenzene was 31.4 kJ per mol. Purified enzyme exhibited a specific activity of 3.1 mol min-1 mg-1 protein and an apparent Km for pyrogallol and 1,2,3,5-tetrahydroxybenzene of 0.70 mM and 0.71 mM, respectively. The enzyme was found to contain per mol heterodimer 1.1 mol molybdenum, 12.1 mol iron and 14.5 mol acid-labile sulfur. Requirement for molybdenum for transhydroxylating enzyme activity was proven also by cultivation experiments. No hints for the presence of flavins were obtained. The results presented here support the hypothesis that a redox reaction is involved in this intermolecular hydroxyl transfer.
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46
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Armstrong SM, Patel TR. Microbial degradation of phloroglucinol and other polyphenolic compounds. J Basic Microbiol 1994; 34:123-35. [PMID: 8014845 DOI: 10.1002/jobm.3620340208] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Biodegradation of phloroglucinol (1,3,5-trihydroxybenzene) and other polyphenolic compounds by microbes may occur by aerobic and anaerobic metabolic pathways. Aerobic microbes may initiate the mineralization of phloroglucinol or other polyphenolics by either a reductive pathway, epoxide formation, or a specific hydroxylating mechanism. Cleavage of the various intermediates of phloroglucinol and polyphenolic degradation may occur by intradiol and extradiol mechanisms. The reductive pathway in contrast to other mechanisms utilized by aerobic microbes, seems both cumbersome and energy wasteful. The degradation of lignin and its associated phenolics follows an enzymatic combustion process which resembles a nonspecific enzyme-catalyzed burning. Anaerobic mineralization of phloroglucinol and its associated polyphenolics by several microbes seems to favour the reductive formation of a dihydrophloroglucinol (1,3-dioxo-5-hydroxycyclohexane), which is cleaved by a specific hydrolase. Mineralization of numerous other polyphenolic compounds by anaerobes seems to utilize phloroglucinol as a central metabolite.
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Affiliation(s)
- S M Armstrong
- Department of Biology and Biochemistry, Memorial University of Newfoundland, St. John's, Canada
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47
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48
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Fernández-Valverde M, Reglero A, Martinez-Blanco H, Luengo JM. Purification of Pseudomonas putida acyl coenzyme A ligase active with a range of aliphatic and aromatic substrates. Appl Environ Microbiol 1993; 59:1149-54. [PMID: 8476289 PMCID: PMC202253 DOI: 10.1128/aem.59.4.1149-1154.1993] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Acyl coenzyme A (acyl-CoA) ligase (acyl-CoA synthetase [ACoAS]) from Pseudomonas putida U was purified to homogeneity (252-fold) after this bacterium was grown in a chemically defined medium containing octanoic acid as the sole carbon source. The enzyme, which has a mass of 67 kDa, showed maximal activity at 40 degrees C in 10 mM K2PO4H-NaPO4H2 buffer (pH 7.0) containing 20% (wt/vol) glycerol. Under these conditions, ACoAS showed hyperbolic behavior against acetate, CoA, and ATP; the Kms calculated for these substrates were 4.0, 0.7, and 5.2 mM, respectively. Acyl-CoA ligase recognizes several aliphatic molecules (acetic, propionic, butyric, valeric, hexanoic, heptanoic, and octanoic acids) as substrates, as well as some aromatic compounds (phenylacetic and phenoxyacetic acids). The broad substrate specificity of ACoAS from P. putida was confirmed by coupling it with acyl-CoA:6-aminopenicillanic acid acyltransferase from Penicillium chrysogenum to study the formation of several penicillins.
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Affiliation(s)
- M Fernández-Valverde
- Departamento de Bioquímica y Biología Molecular, Facultad de Veterinaria, Universidad de León, Spain
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49
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Haddock JD, Ferry JG. Initial steps in the anaerobic degradation of 3,4,5-trihydroxybenzoate by Eubacterium oxidoreducens: characterization of mutants and role of 1,2,3,5-tetrahydroxybenzene. J Bacteriol 1993; 175:669-73. [PMID: 8423143 PMCID: PMC196204 DOI: 10.1128/jb.175.3.669-673.1993] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Chemical mutagenesis and antibiotic enrichment techniques were used to isolate five mutant strains of the obligate anaerobe Eubacterium oxidoreducens that were unable to grow on 3,4,5-trihydroxybenzoate (gallate). Two strains could not transform gallate and showed no detectable gallate decarboxylase activity. Two other strains transformed gallate to pyrogallol and dihydrophloroglucinol but lacked the hydrolase activity responsible for ring cleavage. A fifth strain accumulated pyrogallol, although it contained adequate levels of the enzymes proposed for the complete transformation of gallate to the ring cleavage product. The conversion of pyrogallol to phloroglucinol by cell extract of the wild-type strain was dependent on the addition of 1,2,3,5-tetrahydroxybenzene or dimethyl sulfoxide. This activity was induced by growth on gallate, while the other enzymes involved in the initial reactions of gallate catabolism were constitutively expressed during growth on crotonate. The results confirm the initial steps in the pathway previously proposed for the metabolism of gallate by E. oxidoreducens, except for the conversion of pyrogallol to phloroglucinol.
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Affiliation(s)
- J D Haddock
- Department of Anaerobic Microbiology, Virginia Polytechnic Institute and State University, Blacksburg 24061
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50
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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; 174:3621-8. [PMID: 1592816 PMCID: PMC206050 DOI: 10.1128/jb.174.11.3621-3628.1992] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The enzymes catalyzing the initial reactions in the anaerobic degradation of 2-aminobenzoic acid (anthranilic acid) were studied with a denitrifying Pseudomonas sp. anaerobically grown with 2-aminobenzoate and nitrate as the sole carbon and energy sources. Cells grown on 2-aminobenzoate are simultaneously adapted to growth with benzoate, whereas cells grown on benzoate degrade 2-aminobenzoate several times less efficiently than benzoate. Evidence for a new reductive pathway of aromatic metabolism and for four enzymes catalyzing the initial steps is presented. The organism contains 2-aminobenzoate-coenzyme A ligase (2-aminobenzoate-CoA ligase), which forms 2-aminobenzoyl-CoA. 2-Aminobenzoyl-CoA is then reductively deaminated to benzoyl-CoA by an oxygen-sensitive enzyme, 2-aminobenzoyl-CoA reductase (deaminating), which requires a low potential reductant [Ti(III)]. The specific activity is 15 nmol of 2-aminobenzoyl-CoA reduced min-1 mg-1 of protein at an optimal pH of 7. The two enzymes are induced by the substrate under anaerobic conditions only. Benzoyl-CoA is further converted in vitro by reduction with Ti(III) to six products; the same products are formed when benzoyl-CoA or 2-aminobenzoyl-CoA is incubated under reducing conditions. Two of them were identified preliminarily. One product is cyclohex-1-enecarboxyl-CoA, the other is trans-2-hydroxycyclohexane-carboxyl-CoA. The complex transformation of benzoyl-CoA is ascribed to at least two enzymes, benzoyl-CoA reductase (aromatic ring reducing) and cyclohex-1-enecarboxyl-CoA hydratase. The reduction of benzoyl-CoA to alicyclic compounds is catalyzed by extracts from cells grown anaerobically on either 2-aminobenzoate or benzoate at almost the same rate (10 to 15 nmol min-1 mg-1 of protein). In contrast, extracts from cells grown anaerobically on acetate or grown aerobically on benzoate or 2-aminobenzoate are inactive. This suggests a sequential induction of the enzymes.
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Affiliation(s)
- C Lochmeyer
- Angewandte Mikrobiologie, University of Ulm, Germany
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