ArticleLiterature Review

Microbial Metabolism of Pyridine, Quinoline, Acridine, and Their Derivatives under Aerobic and Anaerobic Conditions

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Abstract

Our review of the metabolic pathways of pyridines and aza-arenes showed that biodegradation of heterocyclic aromatic compounds occurs under both aerobic and anaerobic conditions. Depending upon the environmental conditions, different types of bacteria, fungi, and enzymes are involved in the degradation process of these compounds. Our review indicated that different organisms are using different pathways to biotransform a substrate. Our review also showed that the transformation rate of the pyridine derivatives is dependent on the substituents. For example, pyridine carboxylic acids have the highest transformation rate followed by mono-hydroxypyridines, methylpyridines, aminopyridines, and halogenated pyridines. Through the isolation of metabolites, it was possible to demonstrate the mineralization pathway of various heterocyclic aromatic compounds. By using 14C-labeled substrates, it was possible to show that ring fission of a specific heterocyclic compound occurs at a specific position of the ring. Furthermore, many researchers have been able to isolate and characterize the microorganisms or even the enzymes involved in the transformation of these compounds or their derivatives. In studies involving 18O labeling as well as the use of cofactors and coenzymes, it was possible to prove that specific enzymes (e.g., mono- or dioxygenases) are involved in a particular degradation step. By using H2 18O, it could be shown that in certain transformation reactions, the oxygen was derived from water and that therefore these reactions might also occur under anaerobic conditions.

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... The synthetic 2-pyridone analogs as amrinone and milrinone have excellent vasodilating agents [11], and also used in treatment of the acute congestive heart failure. The core of naturally alkaloids [12] is 2-pyridone used as intermediate in the bacterial metabolism [13]. The 2pyridone derivatives containing amino fragment in position-4 are very interest potential biological as psychotropic, nootropic or antiepileptic activity [14][15][16]. ...
... The structures of 1a-c were confirmed by spectroscopic analysis (IR, 1 H, 13 C NMR and elemental analysis). IR spectra of 1a-c showed the characteristic bands at between 3445-3464, 3191-3195, 2207-2212 and 1650-1673 cm -1 for NH2, NH, C≡N and C=O amides, respectively. ...
... IR spectra of 1a-c showed the characteristic bands at between 3445-3464, 3191-3195, 2207-2212 and 1650-1673 cm -1 for NH2, NH, C≡N and C=O amides, respectively. While, the 1 H, 13 C NMR spectra and their elemental analysis are agreement with the structures and reported in the experimental part. ...
Article
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ABSTRACT A series of O- and N-alkylated 2-pyridone derivatives 2a-c-8a,b were obtained from alkylation of 1a-c with different alkylating agents. Hydrazonolysis of 7a,b followed by reaction with aromatic aldehydes and active methylene reagents affroded the hydrazones 10a,b, 11a,b and 13, in addition to, pyrazole derivative 12. While, the hydrazide 14a,b obtained from hydrazonolysis of the ester 8a,b followed by reaction with ethyl acetoacetate and p-aminoacetophenone to give the corresponding hydrazones 15 and 16, respectively. Diazitization of 1b followed by reaction with active methylene reagents afforded hydrazonid derivatives 17 and 18. Sulpha-drugs 21-23 were obtained from alkylation of 2-thiooxopyridone 19 with chloroacetic acid followed by reaction with different sulphonamide derivatives. The triazole derivatives containing 2- pyridone moiety 24-26 were obtained from the reaction of 2a-c with ethyl 2-azidoacetate via click reaction. All the newly synthesized compounds are elucidated by spectroscopic data (IR, 1H, 13C NMR, Mass spectrometry and elemental analyses. Some of these compounds evaluated against anti-cancer, antioxidant and antimicrobial and gave a good and moderate effect. Keywords: 2-Pyridone derivatives, Alkylation, Hydrazone formation, Sulpha-drugs and Click reaction
... Pyridine (C 5 H 5 N) is heterocyclic aromatic compound that contain a nitrogen atom in its ring structure. It has more potential applications including in the manufacturing of dyes, drugs, explosives and herbicides Kaiser et al., 1996). As a result, finding pyridine in our environment is unavoidable (Chu et al., 2018) with a concentration ranging from 20 to 500 mg/L (Shen et al., 2015a). ...
... As a result, finding pyridine in our environment is unavoidable (Chu et al., 2018) with a concentration ranging from 20 to 500 mg/L (Shen et al., 2015a). Pyridine contamination poses a significant threat to human health (toxic, teratogenic and carcinogenic properties) and ecological systems (Kaiser et al., 1996;Mudliar et al., 2008). Based on this fact, it is a priority hazardous compound registered in the United States Environmental Protection Agency (Padoley et al., 2011). ...
... Since pyridine has a unique future of pi-bond electron density in the ring, it is a hazardous contaminant that challenges the biological wastewater treatment. However, the presence of strong oxidants like HO• as an initial activation step is crucial for biological pyridine degradation (Kaiser et al., 1996;Li et al., 2017;Padoley et al., 2011;Wang et al., 2018a), which is in line with the next part of this study. ...
Article
Pyridine contamination poses a significant threat to human and environmental health. Due to the presence of nitrogen atom in the pyridine ring, the pi bond electrons are attracted toward it and make difficult for pyridine treatment with biological and chemical methods. In this study, coupling Fenton treatment with different biological process was designed to enhance pyridine biotransformation and further mineralization. After Fenton oxidation process optimized, pretreated pyridine was evaluated under three biological (anaerobic, aerobic and microaerobic) operating conditions. Under optimum Fenton oxidation, pyridine (30-75%) and TOC (5-25%) removal efficiencies were poor. Biological process alone also showed insignificant removal efficiency, particularly anaerobic (pyridine = 8.2%; TOC = 5.3%) culturing condition. However, combining Fenton pretreatment with biological process increased pyridine (93-99%) and TOC (87-93%) removals, suggesting that hydroxyl radical generated during Fenton oxidation enhanced pyridine hydroxylation and further mineralization in the biological (aerobic > microaerobic > anaerobic) process. Intermediates were analyzed with UPLC-MS and showed presence of maleic acid, pyruvic acid, glutaric dialdehyde, succinic semialdehyde and 4-formylamino-butyric acid. High-throughput sequencing analysis also indicated that Proteobacteria (35-43%) followed by Chloroflexi (10.6-24.3%) and Acidobacteria (8.0-29%) were the dominant phyla detected in the three biological treatment conditions. Coexistence of dominant genera under aerobic/microaerobic (Nitrospira > Dokdonella > Caldilinea) and anaerobic (Nitrospira > Caldilinea > Longilinea) systems most probably play significant role in biotransformation of pyridine and its intermediate products. Overall, integrating Fenton pretreatment with different biological process is a promising technology for pyridine treatment, especially the combined system enhanced anaerobic (>10 times) microbial pyridine biotransformation activity.
... The derivatives of pyridine are ubiquitous in nature-from universally used cofactors such as nicotinamide adenine dinucleotide (NAD) and pyridoxal phosphate (PLP) to specific plant alkaloids, including nicotine, actinidine, mimosine, etc. Furthermore, synthetic pyridine compounds are widely used as dyes, explosives, pharmaceuticals, and pesticides [1]. ...
... Therefore, bioremediation of persistent pollutants is of considerable practical interest. It is well known that many soil bacteria can degrade various N-heterocycles, such as pyridine, nicotine, and mimosine [1]. Apart from the benefits of mineralization of the toxic xenobiotics, these microbial activities could be implemented in modern biocatalysis. ...
... The residue was recrystallized from propan-2-ol containing a drop of concentrated HCl to give white crystals (0.79 g, 53.5%). 1 H NMR and 13 C NMR spectra were recorded in DMSO-d6 on an Avance III 400 NMR spectrometer at 400 MHz for 1 H and 100 MHz for 13 C; chemical shifts are reported in parts per million relative to solvent resonance signal as an internal standard ( 1 H NMR: δ (DMSO-d6) = 2.50 ppm; 13 C NMR: δ (DMSO-d6) = 39.52 ppm). ...
Article
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N-Heterocyclic compounds are widely spread in the biosphere, being constituents of alkaloids, cofactors, allelochemicals, and artificial substances. However, the fate of such compounds including a catabolism of hydroxylated pyridines is not yet fully understood. Arthrobacter sp. IN13 is capable of using 4-hydroxypyridine as a sole source of carbon and energy. Three substrate-inducible proteins were detected by comparing protein expression profiles, and peptide mass fingerprinting was performed using MS/MS. After partial sequencing of the genome, we were able to locate genes encoding 4-hydroxypyridine-inducible proteins and identify the kpi gene cluster consisting of 16 open reading frames. The recombinant expression of genes from this locus in Escherichia coli and Rhodococcus erytropolis SQ1 allowed an elucidation of the biochemical functions of the proteins. We report that in Arthrobacter sp. IN13, the initial hydroxylation of 4-hydroxypyridine is catalyzed by a flavin-dependent monooxygenase (KpiA). A product of the monooxygenase reaction is identified as 3,4-dihydroxypyridine, and a subsequent oxidative opening of the ring is performed by a hypothetical amidohydrolase (KpiC). The 3-(N-formyl)-formiminopyruvate formed in this reaction is further converted by KpiB hydrolase to 3-formylpyruvate. Thus, the degradation of 4-hydroxypyridine in Arthrobacter sp. IN13 was analyzed at genetic and biochemical levels, elucidating this catabolic pathway.
... Pyridine and its derivatives compose one of the largest classes of N-heterocyclics (Fetzner 1998;Kaiser et al. 1996;O'Hagan 2000;Scriven and Murugan 1996;Sims et al. 1989). They were mainly produced by mining industry, petroleum industry and chemical synthesis industry. ...
... The knowledge gap exists on biodegradation of 3-hydroxypyridine with new strains currently. Although a few intermediates have been reported during 3-hydroxypyridine degradation, the complete degradation pathway of 3-hydroxypyridine remains enigmatic Kaiser et al. 1996). Deciphering the degradation pathway of 3-hydroxypyridine is of scientific significant since it will be helpful for the microbial degradation of 3-hydroxypyridine and related pollutants. ...
... Based on the foregoing reports, 3-hydroxypyridine could be initially metabolized to 2,3-dihydroxypyridine, 3,4-dihydroxypyridine or 2,5-dihydroxypyridine, then the dihydroxypyridine products were transformed to 2,3,6-trihydroxypyridine, which was further cleaved (Fetzner 1998;Kaiser and Bollag 1991;Kaiser et al. 1996). We detected the 2,5-dihydroxypyridine by spectrum scanning analysis and HPLC analysis; however, no 2,3-dihydroxypyridine was observed. ...
Article
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A 3-hydroxypyridine degrading bacterium, designated strain DW-1, was isolated from petroleum contaminated soil in Liao River China. 16S rRNA-based phylogenetic analysis indicates that strain DW-1 belongs to genus Agrobacterium. The optimal cultivation temperature and pH for strain DW-1 with 3-hydroxypyridine were 30 °C and 8.0, respectively. Under optimal conditions, strain DW-1 could completely degrade up to 1500 mg/L of 3-hydroxypyridine in 66 h. The 3-hydroxypyridine degradation pathway of strain DW-1 was suggested by HPLC and LC-MS analysis. The first reaction of 3-hydroxypyridine degradation in strain DW-1 was α-hydroxylation so that the major metabolite 2,5-dihydroxypyridine was produced, and then 2,5-dihydroxypyridine was transformed by a Fe2+-dependent dioxygenase to form N-formylmaleamic acid. N-Formylmaleamic acid will be transformed to maleic acid and fumaric acid through maleamic acid. This is the first report of the 3-hydroxypyridine degradation pathway and the utilization of 3-hydroxypyridine by a Agrobacterium sp. It may be potentially used for the bioremediation of environments polluted with 3-hydroxypyridine.
... Picolinic acid (PA), a pyridine derivative [1], has emerged as an important intermediate from the industrial syntheses of agricultural chemicals, drugs, dyestuffs, dyes, textiles, and mining [1][2][3][4]. It is also a dead-end product of L-tryptophan biosynthesis in living organisms [5][6][7]. ...
... Picolinic acid (PA), a pyridine derivative [1], has emerged as an important intermediate from the industrial syntheses of agricultural chemicals, drugs, dyestuffs, dyes, textiles, and mining [1][2][3][4]. It is also a dead-end product of L-tryptophan biosynthesis in living organisms [5][6][7]. ...
... In many common biological processes, PA is produced from the biodegradation of nitrobenzene, catechol, and anthranilic acid [8,9]. Owing to its hydrophilic nature (water solubility of 887 g/L at 20 • C), PA is easily transported to the aquatic environment and to soil [1,10]. Reports show that the pyridine concentration in wastewaters ranges from 20 to 300 mg/L [4]. ...
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Picolinic acid (PA), a C2-carboxylated pyridine derivative, is a significant intermediate used in industrial production. PA is considered hazardous for the environment and human health. In this study, a Gram-positive bacterium, Rhodococcus sp. PA18, which aerobically utilizes PA as a source of carbon and energy, was isolated. The strain completely degraded 100 mg/L PA within 24 h after induction and formed 6-hydroxypicolinic acid (6HPA), a major PA metabolite, which was identified using ultraviolet-visible spectroscopy, high performance liquid chromatography, and liquid chromatography/time of flight-mass spectrometry analyses. The cell-free extracts converted the PA into 6HPA when phenazine methosulfate was used as an electron acceptor. To our knowledge, this is the first report showing that PA can be metabolized by Rhodococcus. In conclusion, Rhodococcus sp. PA18 may be potentially used for the bioremediation of environments polluted with PA.
... Pyridine and its derivatives belong to N-heterocyclic compounds. Pyridine-contained wastewater mainly stems from mining, coal and shale oil industry processing, wood preservative treatment, medicine and food industry, dye manufacture and agricultural production, etc. [1,2]. Due to its high toxicity and carcinogenicity, pyridines are listed as priority-controlled pollutants by United States Environmental Protection Agency [2]. ...
... However, quantitatively describing the degradation process of 2-PA by microbes are still absent. Moreover, it is also unknown that whether 2-PA can be utilized by other species of microorganism or not [1,2]. In this paper, a strain was able to use 2-PA as a sole source of carbon, nitrogen and energy under aerobic conditions was isolated. ...
... According to Henderson-Hasselbalch equation, when the initial pH of MS medium was 4.0 or 10.0, 2-PA was dissociated and in turn proton was released from the carboxyl group of 2-PA so the value of pH decreased. . In general, the first step for biodegradation of 2-PA is introduced a hydroxyl group on α carbon adjacent to N atom so that 6-HPA is generated [1,2]. In this paper, the experimental findings were consistent with these literatures [1,2]. ...
... The degradation of pyridines has been reported under both oxic and anoxic conditions (Fetzner 1998;Kaiser et al. 1996;Li et al. 2001;Rhee et al. 1997) by pure or mixed cultures (Lodha et al. 2008) across a range of phylogenetically diverse microorganisms including Nocardia sp. (Watson and Cain 1975), Bacillus sp. ...
... Micrococcus luteus was Fig. 1.2 Proposed mechanism for degradation of pyridine via hydration in Bacillus sp. and Nocardia sp. (Kaiser et al. 1996) also reported to utilize pyridine via the pathway leading to succinate ) as proposed by Watson and Cain (1975) for Bacillus sp. 4. However it was observed that in addition to pyridine degradation products, pyridine metabolism by M. luteus also resulted in the accumulation of riboflavin (Sims and O'Loughlin 1992). Although riboflavin was not an intermediate product of pyridine degradation, it was produced only during growth on pyridine, suggesting that pyridine may have played a role in regulating riboflavin production. ...
Chapter
Pyridine derivatives belong to an important class of aromatic compounds that occur largely as a result of human activities, although they are not necessarily xenobiotic compounds. Pyridines can also be derivatized to form a wide variety of xenobiotic compounds ranging from drugs to pesticides. Analogs to phenolic compounds, pyridines exhibit properties that differ in some respects to homocyclic compounds, and this may have profound effects on their biodegradation. The presence of the ring nitrogen defines the reactivity of pyridine derivatives. After 60 years of research into biodegradation of pyridine derivatives, some themes have emerged; however, new discoveries continue to change our understanding of how pyridines are degraded in the environment. This chapter brings together the current state of knowledge on the biodegradation of pyridines.
... nicotinamide will help us to understand the degradation processes of other pyridinic pollutants, such as picloram and diquat 7,15 . ...
... www.nature.com/scientificreports/ the naaD gene encodes the 2,5-DHP 5,6-dioxygenase. The ring-cleavage reaction from 2,5-DHP to N-formylmaleamic acid is one of the key step in pyridinic compounds degradation, and this is due to that 2,5-DHP is the key metabolic intermediate of many pyridine derivatives 7,11,15,16,18 . To confirm its function, the naaD gene was cloned, heterologously expressed in E. coli cells and purified as a homogeneity form. ...
Article
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A novel Alcaligenes sp. strain P156, which can utilize nicotinamide as its sole source of carbon, nitrogen and energy, was enriched and isolated from soil in a solid waste treatment plant. Aerobic growth and degradation with nicotinamide were characterized. Seven nicotinamide degradation-related genes were obtained by sequence alignment from the genome sequence of strain P156. Four genes, designated naaA, naaD, naaE and naaF, were cloned and heterologously expressed. Nicotinamide degradation is initiated by deamination to form nicotinic acid catalyzed by the nicotinamidase NaaA, which shares highest amino acid sequence identity (27.2%) with nicotinamidase from Arabidopsis thaliana. Nicotinic acid is converted to 6-hydroxynicotinic acid, which is further oxidized to 2,5-dihydroxypyridine (2,5-DHP). 2,5-DHP is then transformed to a ring-cleavage product, N-formylmaleamic acid, by an Fe2+ dependent dioxygenase NaaD. N-formylmaleamic acid is transformed to fumaric acid through maleamic acid and maleic acid by NaaE and NaaF, respectively. To our knowledge, this is the first report of the complete microbial degradation of nicotinamide in bacteria. Nicotinamide is considered as a model compound for the study of microbial degradation of pyridinic compounds, and the nicotinamide degrading related genes in strain P156 were distributed differently from the reported similar gene clusters. Therefore, this study contribute to the knowledge on the degradation of pyridinic compounds.
... Pyridine and alkylpyridines are highly water soluble potentially toxic heterocyclic aromatic compounds that contribute towards groundwater contamination (Leenheer and Stuber, 1981). Wastewaters from mines, coal tar-and oil shale-processing operations, wood-preserving facilities, and chemical manufacturing plants add these compounds to surface and ground waters (Kaiser et al., 1996). Incineration, chemical treatment and photo oxidation are some non-biological ways by which they can be treated. ...
... Incineration, chemical treatment and photo oxidation are some non-biological ways by which they can be treated. As reviewed earlier, Arthrobacter, Alkaligenes, Bacillus, Brevibacterium, Nocardia and Pseudomonas sp. are some bacterial species bringing about degradation of these compounds (Kaiser et al., 1996). In addition to these bacteria, certain isolates of Gordonia also bring about degradation of pyridine derivatives. ...
Article
The genus Gordonia includes variedly pigmented aerobic, non-motile, non-sporulating Gram positive (sometimes variable) coccoid forms and rods. Different isolates display distinguishing physiological traits and biochemical properties that are significant in remediation applications. Strains inherently prevalent in soils, seawater, sediments and wastewaters can degrade hydrocarbons. Immobilized cells and microbial consortia containing Gordonia species have been used for in situ applications. Hydrocarbon uptake in this Actinomycete is mediated by attachment to large droplets or by pseudosolubilization of substrates. Hydrocarbons so internalized are degraded by relevant enzymes that are innately present in this microorganism. Wild-type and recombinant strains also mediate desulfurization of polyaromatic sulfur heterocyclic compounds. This organism is metabolically capable of bringing about detoxification of phthalate esters. Two species namely, Gordonia polyisoprenivorans and Gordonia westfalica mediate degradation of rubber and the metabolic pathways involved in the process have been well-understood. Some members are able to transform nitriles into commercially valuable products and others degrade the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine. Cholesterol, pyridine derivatives, fuel oxygenates, thiodiglycol, bis-(3-pentafluorophenylpropyl)-sulfide and 6:2 fluorotelomersulfonate are also biotransformed or degraded by Gordonia species. Some members of this genus are significant in the treatment of wastewaters including those that are rich in steroids and lignin. There are also several patents highlighting the commercial relevance of this genus. On account of its diverse catabolic properties, this Actinomycete has become important in bioremediation of polluted environments.
... NA is a carboxylic derivative of pyridine and is a widely distributed molecule that serves as the sole carbon and nitrogen source for some bacteria and fungi (17,18). NA forms parts of biological molecules such as pyridine cofactors, e.g., NAD(P), and alkaloids, e.g., nicotine and anabasine, and it is essential (in the form of vitamin B 3 ) for organisms that are not able to carry out its synthesis (17). ...
... NA is a carboxylic derivative of pyridine and is a widely distributed molecule that serves as the sole carbon and nitrogen source for some bacteria and fungi (17,18). NA forms parts of biological molecules such as pyridine cofactors, e.g., NAD(P), and alkaloids, e.g., nicotine and anabasine, and it is essential (in the form of vitamin B 3 ) for organisms that are not able to carry out its synthesis (17). The degradation of NA in P. putida depends on the expression of genes from the nic cluster ( Fig. 2A). ...
Article
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This study analyzed the influence of finR deletion on the transcriptomic profile of Pseudomonas putida KT2440. The FinR regulator is widely distributed but poorly studied in diverse proteobacteria. Here, we found 11 operons that potentially are regulated by FinR in KT2440. We further demonstrated that FinR played a positive role and cooperated with the NicR repressor in bacterial nicotinic acid (NA) degradation via regulating the expression of nicC and nicX operons. Furthermore, a transcriptomic analysis also indicated a potentially negative role of FinR in the expression of the hut cluster involved in bacterial histidine utilization. The work deepened our knowledge of FinR function and nicotinic acid degradation in P. putida .
... The microbial degradation of pyridine compounds usually involves the formation of hydroxylated intermediates (Fig. 1). Nevertheless, for decades, it was assumed that the biodegradation of pyridine did not include initial hydroxylation (1). However, more recent results oppose this theory. ...
... While quite a number of different bacteria (Arthrobacter, Rhodococcus, Achromobacter, and Nocardia spp.) have been found to degrade 2HP (1,15,17), neither enzymes nor genes implicated in this process have been extensively studied to date. The most researched degradation pathways of 2HP involve the formation of 2,3,6-trihydroxypyridine (THP). ...
Article
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Microbial degradation of 2-hydroxypyridine usually results in the formation of a blue pigment (nicotine blue). In contrast, the Burkholderia sp. strain MAK1 bacterium utilizes 2-hydroxypyridine without the accumulation of nicotine blue. This scarcely investigated degradation pathway presumably employs 2-hydroxypyridine 5-monooxygenase, an elusive enzyme that has been hypothesized but has yet to be identified or characterized. The isolation of the mutant strain Burkholderia sp. MAK1 ΔP5 that is unable to utilize 2-hydroxypyridine has led to the identification of a gene cluster (designated hpd) which is responsible for the degradation of 2-hydroxypyridine. The activity of 2-hydroxypyridine 5-monooxygenase has been assigned to a soluble diiron monooxygenase (SDIMO) encoded by a five-gene cluster (hpdA, hpdB, hpdC, hpdD, and hpdE). A 4.5-kb DNA fragment containing all five genes has been successfully expressed in Burkholderia sp. MAK1 ΔP5 cells. We have proved that the recombinant HpdABCDE protein catalyzes the enzymatic turnover of 2-hydroxypyridine to 2,5-dihydroxypyridine. Moreover, we have confirmed that emerging 2,5-dihydroxypyridine is a substrate for HpdF, an enzyme similar to 2,5-dihydroxypyridine 5,6-dioxygenases that are involved in the catabolic pathways of nicotine and nicotinic acid. The proteins and genes identified in this study have allowed the identification of a novel degradation pathway of 2-hydroxypyridine. Our results provide a better understanding of the biodegradation of pyridine derivatives in nature. Also, the discovered 2-hydroxypyridine 5-monooxygenase may be an attractive catalyst for the regioselective synthesis of various N-heterocyclic compounds. IMPORTANCE The degradation pathway of 2-hydroxypyridine without the accumulation of a blue pigment is relatively unexplored, as, to our knowledge, no genetic data related to this process have ever been presented. In this paper, we describe genes and enzymes involved in this little-studied catabolic pathway. This work provides new insights into the metabolism of 2-hydroxypyridine in nature. A broad-range substrate specificity of 2-hydroxypyridine 5-monooxygenase, a key enzyme in the degradation, makes this biocatalyst attractive for the regioselective hydroxylation of pyridine derivatives.
... Such substances are found in the wastewater of oil refineries and chemical plants, as well as factories for the production of synthetic rubber, plastics, and dyes (Sophonsiri and Morgenroth, 2004;Ronen et al., 1997). Pyridines are widely used as solvents and starting reagents in organic and bioorganic chemistry (Kaiser et al., 1996). Many works have been devoted for the degradation of pyridine (Padoley et al., 2008). ...
... Heterocyclic aromatic compounds containing nitrogen as a heteroatom like pyridine and its derivatives, occur naturally and in many important synthetic compounds including insecticides, herbicides, pharmaceutical compounds and as a by-product in coal industrial processing. However, pyridine derivatives are approved to be toxic, carcinogenic and harmful to the environment 7,17,23 . They tend to accumulate and contaminate groundwater and soil due to their high solubility compared to homocyclic aromatic compounds 14 . ...
Article
Dead sea soil is known for its hypersaline environment and it is a promising location for isolating extremophilic bacteria with interesting metabolic features. In the current study, we isolated a gram-positive bacterium with the ability to degrade 2,6-dimethyl pyridine (2,6-DMP), also known as 2,6-lutidine, a chemical pollutant. The isolated bacteria were identified using the automated Microscan Walkaway system and the different biochemical reactions were determined. In minimal media using the 2,6-DMP as a sole carbon source, the bacterial isolate showed the ability to convert approximately 40 % of 2,6-DMP within 5 days. The GC-Mass analysis for the degradation products indicated that mono-and dihydroxylation for the pyridine ring and oxidation of one or both of the terminal methyl groups have occurred. Based on this finding, this isolated bacterial can further be utilized for bioremediation purposes.
... Aldehyde oxidases are needed for degradation of diverse aldehydes yielding according carboxylic acids (also in eukaryotes) (Mendel, 2013). While 6-hydroxy-/nicotinate dehydrogenase takes part in degradation of the NAD(P) precursor niacin (vitamin B 3 ) (Kaiser et al., 1996), within metabolism of nucleic acids xanthine dehydrogenase is involved in degradation of purines (Mendel, 2013). Ethylbenzene hydroxylase and 4-hydroxybenzoyl-CoA reductase prepare the anaerobic degradation of ethylbenzene and phenol, respectively, yielding the central intermediate benzoyl-CoA that leads to the anaerobic ring cleavage (Heider et al., 1998;Kniemeyer and Heider, 2001). ...
Article
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The soil microbial community fulfils various functions, such as nutrient cycling and carbon (C) sequestration, therefore contributing to maintenance of soil fertility and mitigation of global warming. In this context, a major focus of research has been on C, nitrogen (N) and phosphorus (P) cycling. However, from aquatic and other environments, it is well known that other elements beyond C:N:P are essential for microbial functioning. Nonetheless, for soil microorganisms this knowledge has not yet been synthesised. To gain a better mechanistic understanding of microbial processes in soil systems, we aimed at summarising the current knowledge on the function of a range of essential or beneficial elements, which may affect the efficiency of microbial processes in soil. This knowledge is discussed in the context of microbial driven nutrient and C cycling. Our findings may support future investigations and data evaluation, where other elements than C:N:P affect microbial processes.
... Members of the genera Rubrivivax and Delftia have been observed to degrade aromatic hydrocarbons or benzene ring structures associated with many alkaloids 61,62 . For the genus Sphingopyxis, reports have demonstrated that members can effectively breakdown antimicrobial alkaloids such as berberine 63 . Lastly, the genus Brevibacterium can effectively degrade the antimicrobial and N-containing pyridine alkaloids 64 . ...
Article
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Insects are known plant pests, and some of them such as Trichoplusia ni feed on a variety of crops. In this study, Trichoplusia ni was fed distinct diets of leaves of Arabidopsis thaliana or Solanum lycopersicum as well as an artifcial diet. After four generations, the microbial composition of the insect gut was evaluated to determine if the diet infuenced the structure and function of the microbial communities. The population fed with A. thaliana had higher proportions of Shinella, Terribacillus and Propionibacterium, and these genera are known to have tolerance to glucosinolate activity, which is produced by A. thaliana to deter insects. The population fed with S. lycopersicum expressed increased relative abundances of the Agrobacterium and Rhizobium genera. These microbial members can degrade alkaloids, which are produced by S. lycopersicum. All fve of these genera were also present in the respective leaves of either A. thaliana or S. lycopersicum, suggesting that these microbes are acquired by the insects from the diet itself. This study describes a potential mechanism used by generalist insects to become habituated to their available diet based on acquisition of phytochemical degrading gut bacteria
... P yridine rings are primary components of pyridoxyl derivatives, natural plant alkaloids, and coenzymes. These compounds are more soluble in water, meaning they can spread into groundwater, which are hazardous to the health of humans and other organisms 1,2 . A pyridine ring opening reaction step is a common feature of most chemical and enzyme-based degradation processes for such pollutants, yet relatively little is known about such reactions, highlighting that gaining a clearer understanding of pyridine ring opening should enable development of management technologies. ...
Article
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Biodegradation of aromatic and heterocyclic compounds requires an oxidative ring cleavage enzymatic step. Extensive biochemical research has yielded mechanistic insights about catabolism of aromatic substrates; yet much less is known about the reaction mechanisms underlying the cleavage of heterocyclic compounds such as pyridine-ring-containing ones like 2,5-hydroxy-pyridine (DHP). 2,5-Dihydroxypyridine dioxygenase (NicX) from Pseudomonas putida KT2440 uses a mononuclear nonheme Fe(II) to catalyze the oxidative pyridine ring cleavage reaction by transforming DHP into N-formylmaleamic acid (NFM). Herein, we report a crystal structure for the resting form of NicX, as well as a complex structure wherein DHP and NFM are trapped in different subunits. The resting state structure displays an octahedral coordination for Fe(II) with two histidine residues (His²⁶⁵ and His³¹⁸), a serine residue (Ser³⁰²), a carboxylate ligand (Asp³²⁰), and two water molecules. DHP does not bind as a ligand to Fe(II), yet its interactions with Leu¹⁰⁴ and His¹⁰⁵ function to guide and stabilize the substrate to the appropriate position to initiate the reaction. Additionally, combined structural and computational analyses lend support to an apical dioxygen catalytic mechanism. Our study thus deepens understanding of non-heme Fe(II) dioxygenases.
... Hydroxypyridines are another compound class that has been associated with bacterial metabolism. Kaiser et al. described specific bacterial reactions for the biosynthesis of 2-hydroxypyridine, 3-hydroxypyridine, and 4-hydroxypyridine [38]. We have previously identified 3-hydroxypyridine sulfate (5) in human samples. ...
Article
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Metabolomics analysis of biological samples is widely applied in medical and natural sciences. Assigning the correct chemical structure in the metabolite identification process is required to draw the correct biological conclusions and still remains a major challenge in this research field. Several metabolite tandem mass spectrometry (MS/MS) fragmentation spectra libraries have been developed that are either based on computational methods or authentic libraries. These libraries are limited due to the high number of structurally diverse metabolites, low commercial availability of these compounds, and the increasing number of newly discovered metabolites. Phase II modification of xenobiotics is a compound class that is underrepresented in these databases despite their importance in diet, drug, or microbiome metabolism. The O-sulfated metabolites have been described as a signature for the co-metabolism of bacteria and their human host. Herein, we have developed a straightforward chemical synthesis method for rapid preparation of sulfated metabolite standards to obtain mass spectrometric fragmentation pattern and retention time information. We report the preparation of 38 O-sulfated alcohols and phenols for the determination of their MS/MS fragmentation pattern and chromatographic properties. Many of these metabolites are regioisomers that cannot be distinguished solely by their fragmentation pattern. We demonstrate that the versatility of this method is comparable to standard chemical synthesis. This comprehensive metabolite library can be applied for co-injection experiments to validate metabolites in different human sample types to explore microbiota-host co-metabolism, xenobiotic, and diet metabolism.
... Moreover, the microbial degradation of 3HP, which has been proposed for several different strains, is thought to proceed via the maleamate pathway (10,(12)(13)(14), 3HP ¡ 2,5-DHP ¡ formate and maleamate ¡ NH 3 and maleate ↔ fumarate, and was recently confirmed in strain DW-1 (9). However, genes and enzymes responsible for 3HP biodegradation have seldom been identified. ...
Article
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3-Hydroxypyridine (3HP) is an important natural pyridine derivative. Ensifer adhaerens HP1 can utilize 3HP as its sole source of carbon, nitrogen and energy to grow, but the genes responsible for the degradation of 3HP remain unknown. In this study, we predicted that a gene cluster, designated 3hpd , might be responsible for the degradation of 3HP. The analysis showed that the initial hydroxylation of 3HP in E. adhaerens HP1 was catalyzed by a four-component dehydrogenase (HpdA1A2A3A4) and led to the formation of 2,5-dihydroxypyridine (2,5-DHP). In addition, the SRPBCC component in HpdA existed as a separate subunit, which is different from other SRPBCC-containing molybdohydroxylases acting on N-heterocyclic aromatic compounds. Moreover, the results demonstrated that the PEP-utilizing protein and pyruvate-phosphate dikinase were involved in the HpdA activity, and the presence of the gene cluster 3hpd was discovered in the genomes of diverse microbial strains. Our findings provide a better understanding of the microbial degradation of pyridine derivatives in nature and indicated that further research on the origin of the discovered four-component dehydrogenase with a separate SRPBCC domain and the function of PEP-utilizing protein and pyruvate-phosphate dikinase might be of great significance. Importance 3-Hydroxypyridine is an important building block for the synthesis of drugs, herbicides and antibiotics. Although the microbial degradation of 3-hydroxypyridine has been studied for many years, the molecular mechanisms remain unclear. Here, we show that 3hpd is responsible for the catabolism of 3-hydroxypyridine. The 3hpd gene cluster was found to be widespread in Actinobacteria , Rubrobacteria , Thermoleophilia , and Alpha- , Beta- , and Gammaproteobacteria , and the genetic organization of the 3hpd gene clusters in these bacteria shows high diversity. Our findings provide new insight into the catabolism of 3-hydroxypyridine in bacteria.
... As a member of the Pseudomonas rRNA homology group III [9], C. testosteroni has complex metabolic pathways and co-factor systems. This species is able to degrade many aromatic compounds, including 3, 4-dichloroaniline, carboxylated pyridine and other pyridine-derived compounds [10][11][12]. Thus, C. testosteroni is a promising microbial chassis that may represent a useful basis on which to construct an efficient protein expression system. ...
Article
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Nicotinate dehydrogenase (NDHase) is a membrane protein with three subunits (ndhS, ndhL, and ndhM), which is difficult to express in a functional form using common hosts such as Escherichia coli, Bacillus subtilis, or Pichia pastoris. Comamonas testosteroni is a suitable microbial chassis for expressing multi-subunit membrane proteins. However, the expression of NDHase in C. testosteroni is extremely low. We have developed a systematic approach to create an efficient protein expression system in C. testosteroni CNB-2 using multi-level N-terminal engineering. We selected a strong promoter for the Mmp1 system that enables control of transcriptional strength in unconventional bacteria. This enhanced the expression of a green fluorescent reporter protein threefold. Following modification of the N-terminal Shine–Dalgarno sequence and rearrangement of amino acid sequence in the starting area of the gene encoding NDHase, enzyme activity increased from 90.6 to 165 U/L. These optimized N-terminal Shine–Dalgarno and amino acid sequences were used to enhance the expression of ndhL subunit and improve the balance expression of three subunits of NDHase, resulting in enzyme activity of 192 U/L that far surpasses the previously reported level. These results highlight a promising strategy for the development of other heterologous expression systems for challenging proteins using unconventional bacteria.
... Nevertheless, none of the genes encoding the biodegradation of pyridine have been described. Moreover, the enzymes involved in the initial stages of ring cleavage are not known (6,20). ...
Article
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Pyridine and its derivatives constitute majority of heterocyclic aromatic compounds that occur largely as a result of human activities and contribute to the environmental pollution. It is known, that they can be degraded by various bacteria in the environment, however, the degradation of unsubstituted pyridine has not yet been completely resolved. In this study we present data on the pyridine catabolic pathway in Arthrobacter sp. 68b at the level of genes, enzymes and metabolites. The pyr genes cluster, responsible for degradation of pyridine, was identified in a catabolic plasmid p2MP. The pathway of pyridine metabolism consisted of four enzymatic steps and ended by formation of succinic acid. The first step in the degradation of pyridine proceeds through a direct ring cleavage catalyzed by a two-component flavin-dependent monooxygenase system, encoded by pyrA and pyrE genes. The genes pyrB , pyrC , and pyrD were found to encode ( Z )- N -(4-oxobut-1-enyl)formamide dehydrogenase, amidohydrolase, and succinate semialdehyde dehydrogenase, respectively. These enzymes participate in the subsequent steps of pyridine degradation. The metabolites of these enzymatic reactions were identified that allowed us to reconstruct the entire catabolic pathway of pyridine in Arthrobacter sp. 68b. Importance The biodegradation pathway of pyridine, a notorious toxicant, is relatively unexplored, as no genetic data related to this process has ever been presented. In this paper, we describe the plasmid-born pyr gene cluster, which encodes the complete set of genes responsible for degradation of pyridine. A key enzyme, the monooxygenase PyrA, which is responsible for the first step of the catabolic pathway, performs an oxidative cleavage of the pyridine ring without typical activation steps, such as reduction or hydroxylation of heterocycle. This work provides new insights into the metabolism of N -heterocyclic compounds in nature.
... Indeed, sequential degradation products were detected through biotransformation by the b-3 consortia ( Fig. 7B and S4). Previous studies have shown that different microbial species degraded hydroxylated and methylated quinoline but with different degradation extents and pathways (Johansen et al. 1997;Kaiser et al. 1996). Thus, the bacterial enrichments used in this study may have formed a syntrophic partnership in buffering redox fluctuation and reducing the overall toxicity of various quinoline degradation products. ...
... It is very important to remove NMP from industrial wastewater. In previous reports, microorganisms have been used to degrade nitrogen-containing heterocyclic pollutants (Kaiser et al., 1996), however, in high salinity conditions, few known microorganisms can effectively degrade NMP due to high osmotic pressure. In this study, a strain that can tolerate a salt concentration of 25% and degrade 93% (under 1% salt) of the 2000 mg/L NMP present in simulated wastewater was found. ...
Article
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N-methylpyrrolidone (NMP), a nitrogen-containing heterocyclic compound, is widely used in lithium batteries and the refining of lubricants. However, it is also very harmful to human health and the environment. Although NMP is biodegradable, industrial high salinity wastewater can stop microorganisms from growing. To effectively degrade NMP in high salinity wastewater, a halotolerant strain CCZU-X was isolated from sea shrimps. The strain was identified as Staphylococcus lentus through morphology observation and 16S rDNA sequencing. The effects of processing conditions such as salt concentration, pH, and temperature on degradation of high salinity NMP-containing wastewater were investigated using single-factor experiments. Quantitative analysis of degradation efficiency of NMP was conducted by high-performance liquid chromatography. The optimal conditions for CCZU-X to degrade NMP in high salinity wastewater were determined to be at pH 7.0 and 35 °C, and the maximum salt tolerance was 25%. Under optimal conditions (pH 7.0, 35 °C, 1% salt, 2000 mg/L NMP), the NMP degradation efficiency of CCZU-X reached 93%. This strain can effectively degrade NMP in high salinity NMP-containing wastewater, thus can be potentially used in industrial applications.
... Activity was calculated according to Kaiser at al (1996): ...
Article
This study aims to determine the effect of solid probiotics used in feed on the growth and survival rate of mantap common carp (Cyprinus carpio). This research was conducted in the Ciparanje Hatchery, Faculty of Fisheries and Marine Sciences, Universitas Padjadjaran. The study was conducted for 60 days from July to September 2018. The research method used was experimental method using Completely Randomized Design (CRD) consisting of 4 treatments and 4 replications, solid probiotics given with treatment A (0 g kg-1), treatment B (0.75 g kg-1), treatment C (1.5 g kg-1) and treatment D (2.25 g kg-1). The parameters observed were average daily gain (ADG), feed efficiency (FE), protease enzyme activity in the digestive tract, survival rate (SR) and water quality which included dissolved oxygen (DO), temperature and pH. Data were analyzed using analysis of variance with F test with 95% confidence level and the difference between treatments was tested by Duncan multiple-range test, then protease enzyme activity and water quality were analyzed descriptively by comparing to related literature and water quality national Indonesian standard. The results showed that the use of probiotics in feed had an effect on the growth of mantap common carp. The addition of probiotics at a dose of 1.5 g kg-1 of feed in treatment gave the optimal yield with the daily growth rate of 2.01%, feed efficiency 38.63%, protease enzyme activity 139.20 unit, and survival rate 83.75%.
... [13,14,29,30,[33][34][35][36] An interesting example of this involves the selective biodepletion of a dilute sample of pyridine isotopologues. While the microbial metabolism of pyridines and other organic bases has been studied extensively, [37] isotope specific studies do not exist, to our knowledge. Table 1 shows GC-MRR results for the biodepletion of 14 N and 15 N pyridine standards in three different microbial cultures/solutions. ...
Article
Full-text available
We designed and demonstrated the unique abilities of the first gas chromatography–molecular rotational resonance spectrometer (GC‐MRR). While broadly and routinely applicable, its capabilities can exceed those of high‐resolution MS and NMR spectroscopy in terms of selectivity, resolution, and compound identification. A series of 24 isotopologues and isotopomers of five organic compounds are separated, identified, and quantified in a single run. Natural isotopic abundances of mixtures of compounds containing chlorine, bromine, and sulfur heteroatoms are easily determined. MRR detection provides the added high specificity for these selective gas‐phase separations. GC‐MRR is shown to be ideal for compound‐specific isotope analysis (CSIA). Different bacterial cultures and groundwater were shown to have contrasting isotopic selectivities for common organic compounds. The ease of such GC‐MRR measurements may initiate a new era in biosynthetic/degradation and geochemical isotopic compound studies.
... Dioxygenases play key roles in the degradation of aromatic compounds. Nicotinic acid (NA) is a carboxylic derivative of pyridine that is widely distributed in nature as part of pyridine cofactors and alkaloids (1). The biochemical pathways involved in the degradation of this N-heterocyclic aromatic compound have been used as a source of novel and unusual enzyme activities as well as metabolic intermediates, such as, 6-hydroxynicotinic acid (6HNA) and 2,5 dihydroxypyridine (2,5 DHP), that can funnel the degradation of toxic compounds of major environmental concern, such as nicotine and hydroxypyridines (2). ...
Article
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2,5-Dihydroxypyridine dioxygenase termed as NicX a Fe2+-dependent dioxygenase that converting 2,5-dihydroxypyridine to N-formylmaleamic acid. However, little information was known about the structural and biochemical characteristics of this enzyme. In this study native and seleno-methionine-substituted (SeMet) proteins have been crystallized by the hanging-drop vapour-diffusion method at 287 K and the preliminary X-ray crystallographic analysis were provided. Diffraction data were collected to a resolution of 1.77 Å and 2.08 Å respectively at Shanghai Synchrotron Radiation Facility, China. The crystals most probably belong to the orthorhombic space group P222 or P2221. The estimated Matthews coefficients is 2.27Å3Da-1, which corresponds to a solvent content of 45.86% in native and 47.60% in selenomethionine-containing NicX. These results will facilitate detailed structural analysis of NicX and further elucidation of its biochemical function. Key words: NicX, 2,5Dihydroxypyridine, selenomethionine, crystallization.
... This is in part due to the vast structural diversity of these compounds. Previous studies have shown the anaerobic biodegradation of N-, S-, and O-containing aromatic compounds under a variety of electron-accepting conditions to be widely distributed across members of both the gram-positive and gram-negative lineages (Berry et al. 1987;Kuhn and Suflita 1989;Bollag and Kaiser 1991;Kaiser et al. 1996;Safinowski et al. 2006). ...
... Anaerobic digestion (AD) as a viable alternative to aerobic treatment technologies has been widely accepted in the past decades for the treatment of refractory organic wastes and some hazardous chemicals because of its exibility, low sludge production, high efficiency and bioenergy generation. [12][13][14] For example, Johansen et al. reported that quinoline was initially oxidized to 2(1H)-quinolones and then oxidized to 3,4-dihydro-2(1H)-quinolones under anaerobic conditions. 15 Li et al. investigated the effective elimination of quinolinic compounds, including quinoline and its derivatives, under denitrifying conditions with acclimated activated sludge. ...
Article
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Quinoline is toxic and difficult to degrade biologically; thus, it is a serious threat to the safety of ecosystems. To promote quinoline reduction, zero-valent iron (ZVI) was introduced into an anaerobic digestion (AD) system through batch experiments. The performance of three different types of ZVI (i.e., iron powder, iron scrap and rusty iron scrap) on quinoline degradation, methane production, formation of volatile fatty acids (VFAs) and chemical oxygen demand (COD) removal were investigated systematically. Compared to the AD system alone, quinoline and COD removal as well as the production of methane and acetic acid were effectively enhanced by ZVI, especially rusty iron scrap. The removal efficiencies of quinoline and COD were increased by 28.6% and 19.9%, respectively. The enhanced effects were attributed to the high accumulation of ferrous ions and high pH self-buffering capability, which were established by ZVI addition. Furthermore, high-throughput sequencing analysis indicated that the functional microorganisms in the ZVI-AD system were higher than in the AD system, and the added types of ZVI played important roles in structuring the innate microbial community in waste activated sludge (WAS). Especially, high enrichment of microorganisms capable of degrading quinoline, such as Pseudomonas and Bacillus, in the coupled system was detected.
... The degradation of quinoline or pyridine in a single contaminant system did not occur by this phenomenon. It was reported that the quinoline could transform into pyridine derivatives by Rhodococcus strain B1 (Schwarz et al. 1989;Kaiser et al. 1996). This result was consistent with that reported by Zhao et al. (2012). ...
Article
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Pyridine is a typical nitrogen heterocyclic and recalcitrant organic compound in coking wastewater. The pyridine-degrading bacterial strain KDPy1 was isolated from aerobic sludge in a coking wastewater treatment plant. The homology analysis based on 16S rDNA sequences suggested that KDPy1 belonged to Rhodococcus sp. The optimum temperature and pH for pyridine degradation by KDPy1 were 37 °C and 7-8, respectively. The strain KDPy1 degraded 1442 mg/L of pyridine nearly 99.6% after 48 h, and high concentration of 1442 mg/L pyridine did not show inhibitory effect to its degradation. The degradation kinetic of pyridine fitted with the Monod model. Furthermore, KDPy1 was capable of degrading pyridine efficiently in the synthetic wastewater containing quinoline and phenol. KDPy1 could degrade pyridine and reduce the total organic carbon (TOC) in the real coking wastewater. These results showed KDPy1 had a potential for improving the removal of pyridine from coking wastewater.
... The compound can oxidatively dimerize to form nicotine blue [44], which is secreted into the medium. However, this has been proposed to be a byproduct, with the major pathway involving formation of maleamate, maleate, and fumarate [45]. ...
Article
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Because of nicotine’s toxicity and the high levels found in tobacco and in the waste from tobacco processing, there is a great deal of interest in identifying bacteria capable of degrading it. A number of microbial pathways have been identified for nicotine degradation. The first and best-understood is the pyridine pathway, best characterized for Arthrobacter nicotinovorans, in which the first reaction is hydroxylation of the pyridine ring. The pyrrolidine pathway, which begins with oxidation of a carbon–nitrogen bond in the pyrrolidine ring, was subsequently characterized in a number of pseudomonads. Most recently, a hybrid pathway has been described, which incorporates the early steps in the pyridine pathway and ends with steps in the pyrrolidine pathway. This review summarizes the present status of our understanding of these pathways, focusing on what is known about the individual enzymes involved.
... But the pyridine is more soluble than their homocyclic analogues, and it can be easily transported through soil and contaminated ground water [5], leading to the increased bioavailability and thus potential toxic effects [5]. The adsorption of pyridine molecule from aqueous solution is more frequently used than other process such as biodegradation [5,6], pervaporation [7] and chemical oxidation [8]. Many studies have explored the pyridine adsorption performance with porous materials such as activated carbons [9][10][11], zeolites [12,13], synthetic apatite [1], polymer resins [15,16], and metal organic frameworks [17,18]. ...
Article
To better understand the adsorption process of pyridine on modified Macronet based adsorbent types MN200 and MN500 were constructed at identical conditions (298, 308, 318 and 328 K) in single adsorption systems. The statistical physic based on the double layer model with two energies has been developed and selected. From theoretical observations and based on the simulation results, the study of the number of molecules per site indicated that the adsorbed molecules aggregate during the adsorption process for the first system (Pyridine/MN200). On the other hand, for the second system (Pyridine/MN500), we can see that the number of molecules per site increase with temperature, which is due to the presence of sulfonic acid functional groups. So because of him the process of aggregation is blocked. Energetically, the interactions between the adsorbed molecules and adsorbent surface were governed by the adsorption energy showing that a physisorption process has occurred. The two adsorption systems were characterized by probable mechanisms describing the interaction, during the adsorption process, between pyridine and the two adsorbents surface MN200 and MN500, in agreement with the statistical physics parameters. Then, the model is applied to calculate thermodynamic functions which govern the adsorption mechanisms such as entropy, free enthalpy of Gibbs and internal energy. These thermodynamics potentials functions are calculated and interpreted.
... This reactivity can lead a molecule to be transformed by different chemical reactions. As an illustration, the first step in the catabolic pathways of the Nheterocycles pyridine, pyridoxine, and N-methylisonicotinate can each begin with different chemical reactions according to the degrading organism (51,55). In other words, the reactions of a metabolic pathway in an organism can also be driven by the nature of the ancestral proteins that have evolved to create new enzyme functions (56,57). ...
Article
Significance The experimental dissection of novel metabolic pathways, from genes and enzymes to metabolites, is a key issue for improving our knowledge of the enzymatic capabilities of the microbial world and providing accurate functional annotation of genomes. We used an integrative methodology combining the phenotyping of a complete genome-scale mutant collection of Acinetobacter baylyi ADP1 with an untargeted liquid chromatography/MS-based approach to uncover the degradation pathway of trigonelline (TG), a widespread osmolyte. We provide extensive information about this unusual N- heterocyclic aromatic degradation route that expands the metabolite repertoire. The occurrence of conserved gene clusters for TG dissimilation in soil, plant-associated, and marine bacteria underlines its environmental abundance.
... This is in part due to the vast structural diversity of these compounds. Previous studies have shown the anaerobic biodegradation of N-, S-, and O-containing aromatic compounds under a variety of electron-accepting conditions to be widely distributed across members of both the gram-positive and gram-negative lineages (Berry et al. 1987;Kuhn and Suflita 1989;Bollag and Kaiser 1991;Kaiser et al. 1996;Safinowski et al. 2006). ...
... In addition to serving as a source of NAD, NA is also a carbon, nitrogen, and energy source for many bacteria which catabolize it by both anaerobic and aerobic routes (12). In Pseudomonas putida strain KT2440, aerobic degradation of NA via the maleamate pathway involves the genes of the nic cluster ( Fig. 1A and B). ...
Article
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Many of the pathogenic species of the genus Bordetella have an absolute requirement for nicotinic acid (NA) for laboratory growth. These Gram-negative bacteria also harbor a gene cluster homologous to the nic cluster of Pseudomonas putida which is involved in the aerobic degradation of NA and its transcriptional control. We report here that BpsR, a negative regulator of biofilm formation and Bps polysaccharide production, controls the growth of Bordetella bronchiseptica by repressing the expression of nic genes. The severe growth defect of the ΔbpsR strain in Stainer-Scholte medium was restored by supplementation with NA, which also functioned as an inducer of nic genes at low micromolar concentrations that are usually present in animals and humans. Purified BpsR protein bound to the nic promoter region, and its DNA binding activity was inhibited by 6-hydroxynicotinic acid (6-HNA), the first metabolite of the NA degradative pathway. Reporter assays with the isogenic mutant derivative of the wild-type (WT) strain harboring deletion in nicA, which encodes a putative nicotinic acid hydroxylase responsible for conversion of NA to 6-HNA, showed that 6-HNA is the actual inducer of the nic genes in the bacterial cell. Gene expression profiling further showed that BpsR dually activated and repressed the expression of genes associated with pathogenesis, transcriptional regulation, metabolism, and other cellular processes. We discuss the implications of these findings with respect to the selection of pyridines such as NA and quinolinic acid for optimum bacterial growth depending on the ecological niche. IMPORTANCE BpsR, the previously described regulator of biofilm formation and Bps polysaccharide production, controls Bordetella bronchiseptica growth by regulating the expression of genes involved in the degradation of nicotinic acid (NA). 6-Hydroxynicotinic acid (6-HNA), the first metabolite of the NA degradation pathway prevented BpsR from binding to DNA and was the actual in vivo inducer. We hypothesize that BpsR enables Bordetella bacteria to efficiently and selectively utilize NA for their survival depending on the environment in which they reside. The results reported herein lay the foundation for future investigations of how BpsR and the alteration of its activity by NA orchestrate the control of Bordetella growth, metabolism, biofilm formation, and pathogenesis.
... N-PAHs are chemicals present in most contaminated sites worldwide and represent two-thirds of known organic xenobiotic chemically synthesized (Rajasekhar et al., 2000;Anyanwu and Semple, 2015a). For example, they are used as industrial solvents, dyes, explosives, pharmaceuticals and pesticides (Kaiser et al., 1996). The US Environmental Protection Agency (USEPA) and International Agency for Research on Cancer (IARC) classified N-PAHs as probable human carcinogens (IARC, 2012). ...
Article
Microbes are susceptible to contaminant effects, and high concentration of chemicals in soil can impact on microbial growth, density, viability and development. The impactof single and binary mixtures ofphenanthrene and its nitrogen-containing polycyclic aromatic hydrocarbon analogues (N-PAHs) on microbial metabolism of 14C-glucose insoilwas measuredovera 90d soil-contact time.Impacts were assessed bymeasuringthe ratesand mean overall extents of mineralisation (%), as well as the incorporation of 14C-glucose into the microbial biomass. The result revealed that the extents of 14C-glucose mineralisation were consistently greater in N-PAH amended soils than the control and phenanthrene soils with increased incubations. This indicates a trend of increasing diversion of C from biosynthesis to maintenance requirement by soil microorganisms. Furthermore, biomass uptake in the amended soils showed reduced substrate utilization (fixed-kEC), suggesting that N-PAHs decreased the amount of substrate-C that was incorporated into the microbial biomass. This however, signifies that N-PAHs imposes oxidative stress on soil microbial community.
... Organic aromatic compounds contain either homocyclic or heterocyclic nucleus and two-thirds of known organic chemicals are heterocyclics containing heteroatom (Kaiser et al., 1996). Organic heterocyclic compounds have cyclic structure(s) with more than one type of dissimilar atoms besides carbon atoms. ...
Article
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Aerobic biodegradation and metabolite identification of indole by the Pseudomonas putida strain mpky-1 isolated from coastal sediment of the Inner Deep Bay of Hong Kong was investigated in this study. This strain had 99.1% similarity with P. putida known. The biochemical degradation pathway of indole involved an initial hydroxylation reaction at the C-2 position to form oxindole followed by a second hydroxylation at the C-3 position to isatin prior to the cleavage of the 5-member carbon ring. This bacterium grew better at 22oC though it was capable of growth at low temperature (15oC in this study) with a longer lag phase. Both the bacterial specific growth rate and the biodegradation rate increased from 0.0035 hr-1 to 0.0249 hr-1 and from 15oC to 30oC, respectively. P. putida mpky-1 grew quicker at pH 6.4 (specific growth rate, 0.0115 hr-1) than pH 7.4 (specific growth rate, 0.0066 hr-1) and pH 8.4 (specific growth rate, 0.036 hr-1) although the lag time of bacterial growth at pH 7.4 and pH 8.4 (15.01 hr and 15.00 hr, respectively) was very similar. The decrease in bacterial growth rate was observed when salinity increased from 5‰ to 30‰. P. putida mpky-1 may adapt to the Mai Po and Inner Deep Bay and degrade indole due to the polluted condition.
Article
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The anaerobic digestion of aqueous condensate from fast pyrolysis is a promising technology for enhancing carbon and energy recovery from waste. Syngas, another pyrolysis product, could be integrated as a co-substrate to improve process efficiency. However, limited knowledge exists on the co-fermentation of pyrolysis syngas and aqueous condensate by anaerobic cultures and the effects of substrate toxicity. This work investigates the ability of mesophilic and thermophilic anaerobic mixed cultures to co-ferment syngas and the aqueous condensate from either sewage sludge or polyethylene plastics pyrolysis in semi-batch bottle fermentations. It identifies inhibitory concentrations for carboxydotrophic and methanogenic reactions, examines specific component removal and assesses energy recovery potential. The results show successful co-fermentation of syngas and aqueous condensate components like phenols and N-heterocycles. However, the characteristics and load of the aqueous condensates affected process performance and product formation. The toxicity, likely resulting from the synergistic effect of multiple toxicants, depended on the PACs’ composition. At 37 °C, concentrations of 15.6 gCOD/gVSS and 7.8 gCOD/gVSS of sewage sludge-derived aqueous condensate inhibited by 50% carboxydotrophic and methanogenic activity, respectively. At 55 °C, loads between 3.9 and 6.8 gCOD/gVSS inhibited by 50% both reactions. Polyethylene plastics condensate showed higher toxicity, with 2.8 gCOD/gVSS and 0.3 gCOD/gVSS at 37 °C decreasing carboxydotrophic and methanogenic rates by 50%. At 55 °C, 0.3 gCOD/gVSS inhibited by 50% CO uptake rates and methanogenesis. Increasing PAC loads reduced methane production and promoted short-chain carboxylates formation. The recalcitrant components in sewage sludge condensate hindered e-mol recovery, while plastics condensate showed high e-mol recoveries despite the stronger toxicity. Even with challenges posed by substrate toxicity and composition variations, the successful conversion of syngas and aqueous condensates highlights the potential of this technology in advancing carbon and energy recovery from anthropogenic waste streams. Graphical Abstract Supplementary Information The online version contains supplementary material available at 10.1186/s40643-024-00791-3.
Thesis
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In this study, firstly, 2-benzylidene-2,3-dihydro-1H-inden-1-one (chalcone) derivates 3a-e) were synthesized by reacting 1-indanone with aromatic aldehydes (2a-e) with aldol condensation in basic medium (Claisen-Schmidt) method at room conditions. Inthe second stage of the study, new 2-alkoxy cyanopyridine derivatives (4a-e, 5a-e) were obtained, in ethanol or methanol, to reflux for 16 hours in the presence of malononitrileand K2CO3. The structures of obtained chlacone derivatives were characterized using spectroscopic methods (NMR, IR). Finally, antimicrobial activities of synthesized 2-ethoxy cyanopyridine derivates (4a-e) were tested in vitro against five human pathogenic bacteria. Penicillin G and Ceftriaxone antibiotics were used as positive control in these tests. MIC (minimum inhibition concentration) values of tested compounds were determined using macro dilution method.
Chapter
Since from the recent past, the attention of industrial wastes has grabbed the focus of the researchers toward designing and development of certain methods or processes in order to lessen the usage and the production of pollutants. With the knowledge of green chemistry, the catalysis using enzymes is the potential method for the production of industrial polymers at a high level without using hazardous reagents and thus curbing the pollution. Enzyme cofactors play a significant role in bio-catalysis since enzymes need them in order to catalyze significantly important reactions in organic synthesis. With the introduction and implementation of stringent processes to discharge waste into the environment, there is a need of the hour to develop alternative methods or processes to treat wastes. There exist large numbers of reported enzymes, which are mentioned in this chapter, from numerous microbes which are playing a major role in treating industrial wastes. Enzymes being specific in nature act and remove pollutants of recalcitrant nature via a certain process like precipitation and then transforming to some other products with certain changes in their characteristics. This results in increasing the susceptibility toward treatment in order to transform the waste into a value-added product. There are numerous unique applications of the catalytic activities, highlighted in the chapter for the proper understanding of the enzymes with the significance of their functions. Nowadays, it has become extensively important to use enzymes rather than hazardous chemicals so as to touch the demands of healthy, clean, and green technologies to protect our earth. This chapter highlights the importance of bio-catalytic reactions to treat various industrial wastes like the tobacco industry, pharmaceutical industry, textile industry, and dye industry with minimum invasiveness.
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In this study, the impact of the length of the alkyl chain and cationic head group on the environmental biodegradability of l -phenylalanine ester derived ILs was systematically studied.
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Book
The toxicity and fate of pharmaceuticals and other emerging micro-organic contaminants in the natural and built environments have been the focus of much research over the last twenty years. Recently, particular focus has been centred on the fate of antimicrobial chemicals, including antibiotics and antifungals. The occurrence of such chemicals in the environment is thought to contribute to the selection of resistance in exposed microorganisms. This special issue (SI) brings together a broad range of recent advances in the field of emerging micro-organic contaminants, ranging from medicinal contaminants to industrial chemicals in the environment. Notable these range from chemical extraction and large-scale analysis to adverse effects on non-target aquatic organisms and potential risk to humans via contaminated foodstuffs. Additionally, this special issue also presents novel contaminant treatment/ degradation methods of both physical and biological nature.
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New pyridine derivatives bearing p-dimethyl amino phenyl and p-bromophenyl moieties at position-4 and 6 have been prepared. The behavior of pyridone derivative 2 toward ethyl chloroacetate followed by hydrazine hydrate gave pyridinyl acetohydrazide derivative 7, and its behavior toward carbon electrophiles has been investigated by its reaction with aromatic aldehydes, ethyl acetoacetate, acetyl acetone, cyclohexanone, phthalic anhydride, maleic anhydride, and isatin affording the pyridine derivatives 8a–e to 16, respectively. Treatment of compound 2 with acrylonitrile in Et3N, yielded the N- alkylated derivative 17. Some pyrazole derivatives have been synthesized by interaction of the chalcone 1 with hydrazine hydrate afforded pyrazole derivative 18. Treatment of compound 18 with benzoyl chloride and or acetic anhydride resulted in the formation of the acylated compounds 19 and 20. Elemental and spectroscopic pieces of evidence characterized all the newly synthesized compounds. Some of the synthesized compounds were tested for their antibacterial activities against Gram-positive and Gram-negative bacteria.
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Picolinic acid is a natural toxic pyridine derived from l -tryptophan metabolism and other aromatic compounds in mammalian and microbial cells. Microorganisms can degrade and utilize picolinic acid for their growth, and thus a microbial degradation pathway of picolinic acid has been proposed. Picolinic acid is converted into 6-hydroxypicolinic acid, 3,6-dihydroxypicolinic acid, and 2,5-dihydroxypyridine in turn. However, there was no physiological and genetic validation for this pathway. This study demonstrated that 3,6-dihydroxypicolinic acid was an intermediate in picolinic acid catabolism and further identified and characterized a novel amidohydrolase 2 family decarboxylase PicC. PicC was also shown to catalyze the decarboxylation of 3,6-dihydroxypicolinic acid into 2,5-dihydroxypyridine. This study provides a basis for understanding picolinic acid degradation and its underlying molecular mechanism.
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Alcaligenesfaecalis strain JQ135 utilizes picolinic acid (PA) as sole carbon and nitrogen source for growth. In this study, we screened a 6-hydroxypicolinic acid (6HPA) degradation-deficient mutant through random transposon mutagenesis. The mutant hydroxylated 6HPA into an intermediate, identified as 3,6-dihydroxypicolinic acid (3,6DHPA) with no further degradation. A novel decarboxylase PicC was identified that was found to be responsible for the decarboxylation of 3,6DHPA to 2.5-dihydroxypyridine. Although, PicC belonged to amidohydrolase_2 family, it shows low similarity (<45%) when compared to other reported amidohydrolase_2 family decarboxylases. Moreover, PicC was found to form a monophyletic group in the phylogenetic tree constructed using PicC and related proteins. Further, the genetic deletion and complementation results demonstrated that picC was essential for PA degradation. The PicC was Zn ²⁺ -dependent non-oxidative decarboxylase that can specifically catalyze the irreversible decarboxylation of 3,6DHPA to 2.5-dihydroxypyridine. The K m and k cat towards 3,6DHPA were observed to be 13.44 μM and 4.77 s ⁻¹ , respectively. Site-directed mutagenesis showed that His163 and His216 were essential for PicC activity. Importance Picolinic acid is a natural toxic pyridine derived from L-tryptophan metabolism and some aromatic compounds in mammalian and microbial cells. Microorganisms can degrade and utilize picolinic acid for their growth, and thus, a microbial degradation pathway of picolinic acid has been proposed. Picolinic acid is converted into 6-hydroxypicolinic acid, 3,6-dihydroxypicolinic acid, and 2,5-dihydroxypyridine in turn. However, there was no physiological and genetic validation for this pathway. This study demonstrated that 3,6DHPA was an intermediate in PA catabolism process and further identified and characterized a novel amidohydrolase_2 family decarboxylase PicC. It was also shown that PicC could catalyze the decarboxylation process of 3,6-dihydroxypicolinic acid into 2,5-dihydroxypyridine. This study provides a basis for understanding PA degradation pathway and the underlying molecular mechanism.
Chapter
Hazardous organic contaminants tend to accumulate in the industrial effluents due to their recalcitrant properties. Approaches used for the hazardous contaminants removal always encounter conflicts between treatment efficiency and economic efficiency. Bioelectrochemical system (BES) is an attractive new type of wastewater treatment technology, which is versatile with the advantages of low energy demand, less sludge production, and synchronous resource recovery. Electrons microbially generated from the anode of BES enable bioremediation processes for removing persistent pollutants in wastewater. Highly oxidized hazardous organic contaminants could be efficiently reduced at abiotic/biocathode driven by bioanodes. This review summarized a series of typical hazardous organic pollutants transformation or degradation in BESs from the views of process operation, functional bacteria, and mechanisms. In addition, as an extent of anaerobic technology, BES coupling with traditional anaerobic process is considered as a promising way to achieve energy-efficient wastewater treatment and deliver scaled-up applications of BESs. Moreover, the main hurdles and future perspectives as well as potential future research are discussed.
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Unlike the benzene ring, the uneven distribution of the electron density of the pyridine ring influences the positional reactivity and interaction with enzymes; e.g., the ortho and para oxidations are more difficult than the meta oxidations. Hydroxylation is an important oxidation process for the pyridine derivative metabolism. In previous reports, the ortho hydroxylations of pyridine derivatives were catalyzed by multicomponent molybdenum-containing monooxygenases, while the meta hydroxylations were catalyzed by monocomponent FAD-dependent monooxygenases. This study identified the new monocomponent FAD-dependent monooxygenase HpaM that catalyzed the ortho decarboxylative hydroxylation of 5HPA. In addition, we found that the maiA gene coding for maleic acid cis-trans isomerase was pivotal for the metabolism of 5HPA, nicotinic acid, and picolinic acid in A. faecalis JQ135. This study provides novel insights into the microbial metabolism of pyridine derivatives.
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Thesis (Ph. D. in Biochemistry)--University of California, Berkeley, Jan. 1957. Includes bibliographical references (leaves 52-54).
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Pyridine and pyridine derivatives occur in the environment as a result of industrial and agricultural activities. The fate of pyridines in the environment is a function of both abiotic and biotic processes, including photochemical transformations, complexation, surface attenuation, transport, and biological degradation. Pyridine is readily degraded in soil, and numerous bacteria isolated from soils or sludges are capable of growing on pyridines as sole sources of carbon and/or nitrogen. Numerous substituted pyridines are also susceptible to biodegradation, although major changes in biodegrada‐bility of the pyridine ring result from slight modification of the nature orposition of ring substituents. Bacteria apparently degrade most simple pyridine derivatives, particularly hydroxypyridines and pyridinecarboxylic acids, via pathways involving hydroxylated intermediates. The initial hydroxylation step in biodegradation of many pyridines is unusual in the incorporation of oxygen derived from water. Data suggest that pyridine and some substituted pyridines are degraded via novel mechanisms, possibly involving initial reductive steps, and lacking hydroxylated intermediates ubiquitous in the metabolism of other aromatic compounds. Data are lacking on the environmental fate of alkyl‐ and chloropyridines, which constitute two of the most important classes of pyridine derivatives detected in environmental samples.
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Chapter
This chapter focuses on the anaerobic degradation of nicotinic acid. Fermentation of nicotinic acid by Clostridium species leads to the formation of 1 mole each of propionate, acetate, CO2, and ammonia. Nicotinic acids containing 14C-labeling in various positions of the pyridine ring is obtained by oxidation of appropriately labeled quinolines. Three compounds, 6-hydroxynicotinic acid (compound I), 1,4,5,6- tetrahydro-6-oxonicotinic acid (compound II), and α-methyleneglutaric acid (compound IV) are isolated as intermediate breakdown products of nicotinic acid. A fourth compound, tentatively identified as 2-formylglutaric acid (compound III), is produced when compound (II) is incubated with crude enzyme preparations. Finally, a fifth compound tentatively identified as dimethylmaleic acid (compound V) is produced when α-methyleneglutaric acid is incubated with crude enzyme preparations. The assay method and purification procedure of ring-labeled nicotinic acids, 6-hydroxynicotinic acid-7-14C and synthesis of 1,4,5,6-tetrahydro-6-oxonicotinic acid are also provided. A synthesis is developed by taking advantage of a ring-cleavage reaction of coumalic acid. The conversion of nicotinic acid to 6-hydroxynicotinic acid is also outlined.
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As a result of screening a large number of culture collections and cultures of microscopic fungi isolated from soil, strains able to transform ethylpyridines were found. It is shown that oxidation of the methylene group leads to the formation of optically active (-)-(1-hydroxyethyl)pyridines. Along with this, oxidation of methyl groups and heterocyclic nitrogen atoms occurs with the formation of the corresponding primary alcohols and N-oxides. In the case of biotransformation of 2-ethylpyridine, optically active hydroxyethylpyridine was practically the only reaction product
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From soil and water samples and from activated sludge of a sewage treatment plant 16 bacterial strains were isolated which utilize quinoline as sole carbon and nitrogen source. The majority of the strains are Gram-negative, aerobic, polarly flagellated rods which do not form spores. They are catalase positive and cytochrome oxidase positive. Some strains can grow anaerobically at the expense of nitrate. Some of them accumulate poly-β-hydroxybutyrate as cellular reserve material. 13 strains could be identified as members of the genus Pseudomonas. Three strains show a positive Gram strain and were identified as Rhodococcus species.
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A bacterium which grew on 4-carboxy-1-methylpyridinium chloride (N-methyl-isonicotinic acid, MINA) as sole source of carbon and nitrogen was isolated from soil. The N-methyl group of this molecule was shown to be the source of methylamine detected as a metabolic product. Methylamine was identified by chromatography, isotope dilution and oxidation by a bacterial methylamine dehydrogenase. The stoichiometry of the process showed one molecule of methylamine arising from one molecule of the substrate.
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The fate of pyridine and 25 substituted pyridines in soil (Aeric Ochraqualfs) was examined by measuring the quantity remaining and the inorganic N released as a result of degradation of the pyridine ring for a period of 64 d. Each compound was added to soil at 2 mmol kg . Compounds studied included pyridine substituted with one or two hydroxyl, carboxyl, chlorine, amine, or methyl groups. During the 64-d incubation period, extractability of pyridine derivatives with 2 M KCl + 0.01 M HCl decreased from an average of 88 +/- 8.8% to essentially 0 for all compounds except aminopyridines. From 36 to 94% of added aminopyridines was recovered after 64 d of incubation. Degradation of the majority of pyridine derivatives was confirmed by accumulation of N in amounts equivalent to 61 to 80% of the decrease in extractable pyridines at 64 d of incubation. Degradation of unsubstituted pyridines occurred within 8 d, whereas most hydroxypyridines were degraded within 32 to 64 d. Pyridinecarboxylic acids appear to be the most labile group of pyridine derivatives and were dissipated from soil in 4 to 16 d. Most chloropyridines persisted in soil and became weakly associated with some insoluble soil component. However, 4-chloropyridine degraded in 16 d. Aminopyridines resisted degradation in soil while methylpyridines were degraded in 8 to 32 d. Degradability of the compounds generally followed the order pyridine-carboxylic acids > pyridine = mono-hydroxypyridines > methylpyridines > aminopyridines and chloropyridines. This trend was consistent with previous results on biodegradability of the compounds in soil suspension cultures.
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Metabolism of the aza-arenes quinoline, isoquinoline, quinazoline, and quinoxaline by a mutant strain of the bacterium Pseudomonas putida resulted in attack at the carbocyclic ring (to yield stable cis-dihydrodiols and phenols) and at the heterocyclic ring (to yield phenols and ring cleavage products).
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Attempts have been made to correlate the chemical structure of 38 pyridine derivatives, including two herbicides, picloram (Tordon) and Daxtron and a nitrification inhibitor (N-Serve), with their resistance to attack by soil microorganisms under aerobic and anaerobic conditions and with their herbicidal effect upon lucerne (Medicago sativa L., Hunter River).There was a rough correlation between the number of substituents in the pyridine ring and both recalcitrance and phytotoxicity, so that compounds with four to five substituents were mostly more persistent and herbicidal than those with one to two. Decomposition was often slower under anaerobic than aerobic conditions. Chlorination often conferred persistence and herbicidal properties, but some non-chlorinated pyridines also were markedly resistant to microorganisms and harmful to lucerne. The prospect of making picloram and Daxtron more biodegradable by altering their substituents but retaining their herbicidal properties, seems remote. Substituting -OH for -Cl in position six of picloram left its properties the same. Removal of the -COOH from picloram had no effect on persistence but reduced herbicidal activity more than one hundred-fold. Removal of -Cl from position five and -NH2 did not affect persistence and reduced phytotoxicity only 10-fold.Replacing -OH of Daxtron by -NH2 hardly affected resistance to microbial degradation but greatly lowered its herbicidal potency.Removal of -CCl3 from N-Serve or substituting -COOH in its place had no effect on biodegradation but increased phytotoxicity.Among mono- and disubstituted pyridines, comparisons of different substituents at positions two, three or four showed that -COOH at any position stimulated decomposition more often than any other substituent, while -Cl inhibited it most often; effects on phytotoxicity were more complicated. Substitution of -NH2 or -OH usually increased persistence but had inconsistent effects on phytotoxicity. Biodegradation was favoured by -CH3 in alpha or beta positions, but gamma -CH3 usually increased resistance to attack by soil microorganisms. Phytotoxicity was increased slightly by -CH3 groups.
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Nocardia rhodochrous LL100-21 utilized 2-, 3- or 4-cyanopyridine (2-, 3- or 4-pyridine carbonitrile) and the corresponding pyridine carboxamides as sources of nitrogen for growth. Studies with intact bacteria and cell-free extracts indicated that 3-cyanopyridine was hydrolysed directly to nicotinic acid by an inducible 3-cyanopyridinase enzyme (a nitrilase), and that the organism also possessed a separately inducible nicotinamidase. In cultures supplied with 3-cyanopyridine or nicotinamide as the source of nitrogen the compounds were hydrolysed to form ammonia, which was utilized for growth, and nicotinic acid, which was not further metabolized and accumulated in the culture medium. In cultures containing 3-cyanopyridine, which had a bacteriostatic effect, little growth occurred until all the nitrile had been converted to nicotinic acid; the specific activity of 3-cyanopyridinase of the bacteria was highest in the early exponential phase of growth and had disappeared by the stationary phase. Measurements of the abilities to either oxidize or release ammonia from heterocyclic, aromatic and aliphatic nitriles and amides by bacteria grown on the various substrates indicated that benzonitrile acted as both a substrate and an inducer of 3-cyanopyridinase activity, whereas benzamide acted as a substrate and an inducer of nicotinamidase. These enzymes are induced separately from the acetonitrile hydratase/acetamidase enzyme system of this bacterium.
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The prevalence of bacteria in the environment that catabolise synthetic phthalic acids (PAs) might be related to the natural occurrence of pyridine dicarboxylic acids (PDCAs). However, the bacterial metabolism of o-phthalic acid (phthalic acid) and its PDCA analogs was mostly exclusive. An exception was the oxidation of 2:3 and 3:4-PDCAs by a marine bacterium (Strain OP-1) when grown on phthalic acid. The metabolism of PDCAs by Strain OP-1 was induced by phthalic acid and, as for phthalate catabolism, the metabolism of 2:3-PDCA required Na+ ions.
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A denitrifying bacterium capable of pyridine degradation was isolated from contaminated soil. The Gram-negative bacterium, which was identified as an Alcaligenes sp., rapidly metabolized pyridine under anaerobic conditions with nitrate as electron acceptor. [14C]Pyridine was converted to 14CO2, unidentified polar metabolic products, and labeled biomass. During pyridine metabolism, nitrate was reduced to nitrogen gas via nitrite and nitrous oxide. The molar ratio of pyridine to nitrate strongly affected pyridine metabolism. Maximum pyridine degradation occurred at a nitrate concentration above 5 mM, a temperature of 22–36 °C, and a pH of 6.8–8.0. Key words: pyridine, anaerobic metabolism, denitrifying bacteria, Alcaligenes sp.
Article
A Nocardia sp., which utilises pyridine N-oxide (PNO), 2-hydroxypyridine, and pyridine as sole sources of carbon, nitrogen, and energy, has been isolated from soil by enrichment on PNO. PNO-adapted cells rapidly oxidized PNO and 2-hydroxypyridine; pyridine was oxidized very slowly. 2-Hydroxy pyridine- and pyridine-adapted cells oxidized their respective substrates, but PNO was not oxidized. Dihydroxypyridines did not accumulate during growth of the organism, but the formation of blue pigments during fermentation of PNO and 2-hydroxypyridine suggested their transient participation. The pigment has been characterized as 4,5,4′,5′-tetrahydroxy-3,3′-diazadiphenoquinone-(2,2′). No pigment was formed during pyridine metabolism. 2,5-Dihydroxypyridine was oxidized by PNO- and 2-hydroxypyridine-adapted but not by pyridine-adapted cells. Succinic semialdehyde was characterized as the intermediate of pyridine metabolism from semicarbazide-inhibited cultures; it was rapidly oxidized by pyridine-adapted cells. Pyridine N-oxide is therefore metabolized in this Nocardia sp. via 2-hydroxypyridine and 2,5-dihydroxypyridine, but these compounds do not serve as intermediates of pyridine metabolism.
Article
Laboratory studies were conducted to determine whether the organophosphorus insecticide chlorpyrifos undergoes enhanced microbial degradation in soil. Repeated treatment of soils in the laboratory with chlorpyrifos did not alter the chlorpyrifos degradation rates or product distributions observed in four soils. Likewise, soils from three plots that received annual field applications of chlorpyrifos for 2-4 years did not develop an enhanced rate of chlorpyrifos degradation in laboratory degradation studies as compared to soils from untreated plots. Soils from fields in which a number of insecticides failed to control the target insect pests displayed short chlorpyrifos half-lives of between 4 and 9 days. The degradation of chlorpyrifos in these "problem" soils, which were highly alkaline (pH ≥8), was not microbially mediated and appeared to be a hydrolytic process. Accumulation or mineralization of the major chlorpyrifos hydrolysis product, 3,5,6-trichloro-2-pyridinol, was unrelated to the rate of chlorpyrifos hydrolysis observed. Results indicate that chlorpyrifos is not susceptible to enhanced microbial degradation and repeated chlorpyrifos application should have no effect on its persistence or efficacy.
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Pseudoöxynicotine (III) and the previously unknown 3-nicotinoylpropionic acid (IV) were isolated from microbial degradation products of a medium containing nicotine.
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Anaerobic microbial transformation of a polynuclear nitrogen heterocycle, acridine, was studied in laboratory microcosms with three different inocula: a stabilized, mixed culture growing on ferulic acid that was originally enriched from anaerobic sewage sludge, and sulfate-reducing and methanogenic aquifer materials from two sites at a groundwater aquifer contaminated by landfill leachate. Acridine degradation was investigated under methanogenic, denitrifying and sulfate-reducing conditions at concentrations of 1 to 6 μg/ml. Substrate degradation was followed using two standard analytical techniques (HPLC and GC-MS) and a new, in situ remote fiber spectroscopic (RFS) technique. This RFS was used successfully to follow changes in concentration of acridine with time, which indicates the technique has a significant potential for monitoring the degradation process in environmental media. Acridine was degraded extensively in one to three weeks under each of the conditions studied. A range of heterocyclic, homocyclic aromatic and aliphatic intermediates was identified by GC-MS analyses. On the basis of these compounds, a tentative route of anaerobic acridine transformation is proposed that begins with oxidation and proceeds through the common degradative route for oxidized aromatic compounds.
Article
The potential for anaerobic biodegradation of 12 heterocyclic model compounds was studied. Nine of the model compounds were biotransformed in aquifer slurries under sulfate-reducing or methanogenic conditions. The nitrogen and oxygen heterocyclic compounds were more susceptible to anaerobic biodegradation than those compounds containing a sulfur heteroatom. Carboxy-substituted compounds were anaerobically metabolized more readily than unsubstituted or methylated analogues. In methanogenic incubations, 47 to 84% of the expected amount of carbon in pyridine, 4-picoline, nicotinic acid and 2-thiophene carboxylic acid was recovered as methane. In contrast, only small amounts of methane were detected in aquifer slurries amended with compounds containing an oxygen heteroatom, even though a decrease in the parent substrate concentration occurred. Pyridine, 2-picoline and 4-picoline were biotransformed within three months under sulfate-reducing conditions. However, longer incubation times were required for the degradation of these substrates in methanogenic aquifer slurries. A literature survey reveals the widespread contamination of ground waters with heterocyclic compounds from waste management practice and fossil-fuel-related industries.
Article
Relationships between structure and biodegradability were evaluated for 28 pyridine derivatives in nutrient solutions inoculated with soil and incubated at 24°C. Compounds studied included pyridine; mono- and disubstituted pyridinecarboxylic acids; and hydroxy-, chloro-, amino-and methylpyridines. Disappearance of the pyridine added was measured by UV spectrophotometry, and the ammonium released by cleavage of the pyridine ring was measured by colorimetry. Volatilization was estimated by analysis of the pyridines collected on the polyurethane foam stoppers used to plug the incubation vessels; sorption by soil was estimated from the initial decrease in solution concentration upon addition of soil. Pyridinecarboxylic acids, monohydroxypyridines and the unsubstituted pyridine ring did not volatilize and were degraded within 7 to 24 d. Methylpyridines were intermediate in degradability, disappearing in from less than 7 to more than 30 d. None of the aminopyridines was completely degraded in 30 d. Of the chloropyridines tested, only 4-chloropyridine was completely degraded in 24 d. The susceptibility of 4-chloropyridine to degradation may be attributed to the ease with which a chlorine group is removed from position 4 on the pyridine ring. No degradation was detected in 30 d for any of the other chloropyridines. Chloro-and methylpyridines volatilized extensively.
Article
Infiltration of wastes containing creosote and pentachlorophenol from surface impoundments at an abandoned wood-treatment facility near Pensacola, Florida, resulted in contamination of the underlying sand and gravel aquifer. Pond sludges and sediments near the source were contaminated with 2- to 5-ring azaarenes having log Kow values of from 2.0 to 5.6. However, the ground water contained only azaarenes and their oxygenated and methylated derivatives having log Kow values of less than 3.5. These compounds also were present in coal tar-contaminated ground water at a site near St. Louis Park, Minnesota. Laboratory anaerobic degradation studies and on-site observations indicated that oxygenated azaarenes probably were biotransformation products of reactions mediated by indigenous microbial populations. Microbial N-methylation, C-methylation and O-methylation reactions are reported here for the first time. In the presence of nutrients and carbon sources such as acetate and propionate, all azaarenes studied were either partially or completely degraded. Evidence for the microbial degradation of azaarenes in ground water from anaerobic zones is presented. Oxygenated azaarenes were relatively more water-soluble, mobile and persistent in hydrogeologic environments.
Article
The pathways in the microbiological transformation of pyridine and its derivatives (alkylpyridines, hydroxypyridines, pyridinecarboxylic acids, alkaloids, and condensed systems with a pyridine ring) under the influence of various microorganisms and several enzyme systems are examined. It is noted that oxidation, reduction, hydrolysis, and destruction of the aromatic ring are the most characteristic processes.
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Pyridine and its derivatives have been found as pollutants in the environment. Although alkylpyridines constitute the largest class of pyridines contaminating the environment, little information is available concerning the fate and transformation of these compounds. In this investigation ethylpyridines have been used as model compounds for investigating the biodegradability of alkylpyridines. A mixed culture of ethylpyridine-degrading microorganisms was obtained from a soil that had been exposed to a variety of pyridine derivatives for several decades. The enrichment culture was able to degrade 2-, 3-, and 4-ethylpyridine (100 mg/L) at 28 C and pH 7 within two weeks under aerobic conditions. The degradation rate was greatest for 2-ethylpyridine and least for 3-ethylpyridine. Transformation of ethylpyridines was dependent on substrate concentration, pH, and incubation temperature. Studies on the metabolic pathway of 4-ethylpyridine revealed two products; these chemicals were identified by MS and NMR analyses as 4-ethyl-2(1H)-pyridone and 4-ethyl-2-piperidone. 6-Ethyl-2(1H)-pyridone was determined to be a product of 2-ethylpyridine degradation. These results indicate that the transformation mechanism of ethylpyridines involves hydroxylation and reduction of the aromatic ring before ring cleavage.
Article
A denitrifying bacterium capable of pyridine mineralization under anaerobic conditions was isolated from polluted soil. The bacterium, identified as Alcaligenes sp., was used in inoculation experiments. A subsurface sediment from a polluted site was amended with 10 g/g 14C-labeled pyridine, and 250 g/g nitrate, and then inoculated with the bacterium at an inoculum size of 4.5 107 cells/g. After 44 h incubation at 28 C under anaerobic conditions, 67% of the radioactivity was recovered as 14CO2: 2% was extracted with 50% methanol, and 24% was recovered by combustion of the sediment. Analysis of the methanol extract revealed that no pyridine could be detected in the inoculated sediment. In contrast, mineralization of pyridine by the native microflora in the sediment occurred much more slowly: after 7 days of incubation only 10% of the added radioactivity was recovered as 14CO2. At an inoculum size of 2 103 cells/g pyridine mineralization was not as effective as at an inoculum size of 2 107 cells/g. It is presumed that suppression of the introduced bacteria by the native microflora of the sediment prevents degradation at a low inoculum size. Amending the sediment with nitrate and phosphate improved pyridine mineralization by the introduced bacterium. These findings demonstrate the feasibility of using soil inoculation anaerobically for the bioremediation of pyridine-polluted soils.
Article
The strains NAV-1, NAV-2, NAV-3 of new nonsporing sulfate-reducing bacteria with spherical to oval motile cells were isolated with nicotinic acid as electron donor and carbon source. All strains were obtained from marine sediment samples. Growth occurred in defined anaerobic salt water media supplemented with biotin and thiamine as growth factors. Utilization of nicotinic acid depended on the addition of selenite (10-8–10-7 mol/l); requirement for molybdate was not detected. Further compounds utilized as electron donors and carbon sources were hydrogen plus carbon dioxide, formate, acetate, propionate, higher fatty acids up to 16 carbon atoms, alcohols, pyruvate, malate, fumarate, succinate, glutarate, glutamate and pimelate. On hydrogen plus carbon dioxide or on formate, slow growth was obtained without an additional organic carbon source. Growth on acetate or propionate as sole organic substrates was possible, however, it was extremely slow. Stoichiometric measurements revealed that nicotinic acid was completely oxidized to carbon dioxide and ammonia. The average growth yield was 38 g cell dry weight per mol of nicotinic acid used. 3-Phenylpropionate was oxidized to carbon dioxide and benzoate; benzoate could not be oxidized further. The strains were able to reduce sulfite or thiosulfate instead of sulfate. No growth on organic compounds was observed in the absence of an electron acceptor. In the cell membrane fraction, b-type cytochrome was identified; desulfoviridin was not detected. Cell-free extracts oxidized nicotinic acid, nicotinamide or pyrazine-2-carboxylic acid with methylviologen as electron acceptor. Strain NAV-1 is described as type strain of the new species Desulfococcus niacini.