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1.
A strain of Pseudomonas spp. was isolated from nitrobenzene-contaminated soil on 4-nitrotoluene as the sole source of carbon, nitrogen, and energy. The organism also grew on 4-nitrobenzaldehyde, and 4-nitrobenzoate. 4-Nitrobenzoate and ammonia were detected in the culture fluid of glucose-grown cells after induction with 4-nitrotoluene. Washed suspensions of 4-nitrotoluene- or 4-nitrobenzoate-grown cells oxidized 4-nitrotoluene, 4-nitrobenzaldehyde, 4-nitrobenzyl alcohol, and protocatechuate. Extracts from induced cells contained 4-nitrobenzaldehyde dehydrogenase, 4-nitrobenzyl alcohol dehydrogenase, and protocatechuate 4,5-dioxygenase activities. Under anaerobic conditions, cell extracts converted 4-nitrobenzoate or 4-hydroxylaminobenzoate to protocatechuate. Conversion of 4-nitrobenzoate to protocatechuate required NADPH. These results indicate that 4-nitrotoluene was degraded by an initial oxidation of the methyl group to form 4-nitrobenzyl alcohol, which was converted to 4-nitrobenzoate via 4-nitrobenzaldehyde. The 4-nitrobenzoate was reduced to 4-hydroxylaminobenzoate, which was converted to protocatechuate. A protocatechuate 4,5-dioxygenase catalyzed meta-ring fission of the protocatechuate. The detection of 4-nitrobenzaldehyde and 4-nitrobenzyl alcohol dehydrogenase and 4-nitrotoluene oxygenase activities in 4-nitrobenzoate-grown cells suggests that 4-nitrobenzoate is an inducer of the 4-nitrotoluene degradative pathway. 相似文献
2.
Fungal cytochrome P450s catalyzing hydroxylation of substituted toluenes to form their hydroxymethyl derivatives 总被引:2,自引:0,他引:2
The degradation of a series of nitroaromatic compounds by the lignin-degrading fungus Phanerochaete chrysosporium was examined. From 4-nitrotoluene (4-NT), several metabolic intermediates were identified. Initially, 4-NT was converted to 4-nitrobenzyl alcohol (4-NBA), followed by the oxidation reactions to form 4-nitrobenzaldehyde and 4-nitrobenzoic acid, albeit slowly. Exogenously added 4-nitrobenzaldehyde and 4-nitrobenzoic acid were predominantly reduced to 4-NBA. The fungal formation of 4-NBA was inhibited by piperonyl butoxide, a cytochrome P450 inhibitor, suggesting the involvement of cytochrome P450 in the hydroxylation of the methyl group. Similarly, 2-, and 3-nitrotoluenes and 4-chlorotoluene were converted to the corresponding arylalcohols by P. chrysosporium. On the other hand, toluene and 4-methoxytoluene were not converted. Thus, P. chrysosporium possesses an alkyl hydroxylation activity against aromatic compounds substituted with a strong electron-withdrawing group. 相似文献
3.
4.
Three bacterial strains utilizing 3-nitrotoluene (3-NT) as a sole source of carbon, nitrogen and energy were isolated from an industrial wastewater treatment plant. Biochemical tests and 16S rDNA sequence analysis revealed that the isolated strains belonged to Diaphorobacter sp. Detailed studies were carried out with Diaphorobacter sp. strain DS2. Degradation of 3-NT by Diaphorobacter sp. strain DS2 was accompanied by the release of nitrite in the culture broth with increase in biomass. Total organic carbon analysis confirmed the extensive mineralization of 3-NT. The strain could degrade 3-methylcatechol, 4-methylcatechol and catechol easily suggesting that the degradation pathway could involve these as possible intermediates. Successful PCR amplification of the oxygenase large subunit and the presence of high activity for catechol 2,3-dioxygenase in the crude cell lysate further confirmed that the degradation of 3-NT occurred through (methyl)catechol intermediates in strain DS2. The strain DS2 was found to degrade other isomers of mononitrotoluene (2-NT and 4-NT) and nitrobenzene as well. 相似文献
5.
A novel 4-nitrotoluene-degrading bacterial strain was isolated from pesticides contaminated effluent-sediment and identified as Rhodococcus pyridinivorans NT2 based on morphological and biochemical properties and 16S rDNA sequencing. The strain NT2 degraded 4-NT (400 mg l?1) with rapid growth at the end of 120 h, reduced surface tension of the media from 71 to 29 mN m?1 and produced glycolipidic biosurfactants (45 mg l?1). The biosurfactant was purified and characterized as trehalose lipids. The biosurfactant was stable in high salinity (10 % w/v NaCl), elevated temperatures (120 °C for 15 min) and a wide pH range (2.0–10.0). The noticeable changes during biodegradation were decreased hydrophobicity; an increase in degree of fatty acid saturation, saturated/unsaturated ratio and cyclopropane fatty acid. Biodegradation of 4-NT was accompanied by the accumulation of ammonium (NH4 +) and negligible amount of nitrite ion (NO2 ?). Product stoichiometry showed a carbon (C) and nitrogen (N) mass balance of 37 and 35 %, respectively. Biodegradation of 4-NT proceeded by oxidation at the methyl group to form 4-nitrobenzoate, followed by reduction and hydrolytic deamination yielding protocatechuate, which was metabolized through β-ketoadipate pathway. In vitro and in vivo acute toxicity assays in adult rat (Rattus norvegicus) showed sequential detoxification and the order of toxicity was 4-NT >4-nitrobenzyl alcohol >4-nitrobenzaldehyde >4-nitrobenzoate >> protocatechuate. Taken together, the strain NT2 could be used as a potential bioaugmentation candidate for the bioremediation of contaminated sites. 相似文献
6.
In vivo construction of a hybrid pathway for metabolism of 4-nitrotoluene in Pseudomonas fluorescens.
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Pseudomonas fluorescens 410PR grows on 4-nitrobenzoate but does not metabolize 4-nitrotoluene. The TOL pWW0 delta pm plasmid converts 4-nitrotoluene into 4-nitrobenzoate through its upper pathway, but it does not metabolize 4-nitrobenzoate. P. fluorescens 410PR(pWW0 delta pm) transconjugants were isolated and found to be able to grow on 4-nitrotoluene. This phenotype was stable after growth for at least 300 generations without any selective pressure. P. fluorescens 410PR(pWW0 delta pm) converted 4-nitrotoluene into 4-nitrobenzoate via 4-nitrobenzylalcohol and 4-nitrobenzaldehyde. 4-Nitrobenzoate was metabolized via 4-hydroxylaminobenzoate and finally yielded NH4+ and 3,4-dihydroxybenzoate, which was mineralized. 相似文献
7.
The mononitrotoluenes are important industrial chemicals which display isomeric specificity in their ability to induce hepatic DNA excision repair in Fischer-344 rats. Covalent binding of the structurally related hepatocarcinogen, 2,6-dinitrotoluene, to hepatic DNA is markedly decreased by prior administration of the sulfotransferase inhibitors pentachlorophenol (PCP) and 2,6-dichloro-4-nitrophenol (DCNP). The objectives of this study were to determine whether hepatic macromolecular covalent binding of the mononitrotoluene isomers differed and to determine whether covalent binding of the mononitrotoluenes to hepatic DNA in vivo was decreased by inhibitors of sulfotransferase. Male Fischer-344 rats were given a single oral dose of [ring-U-14C]-2-, 3- or 4-nitrotoluene (2-, 3- or 4-NT) and killed at various times thereafter. Livers were removed and analyzed for total and covalently bound radiolabel. Maximal concentrations of total radiolabel were observed between 3 and 12 h after the dose, and there were no large differences among the 3 isomers in peak concentrations achieved. Covalent binding to hepatic macromolecules was maximal 12 h after administration for all three isomers. Thereafter, concentrations of covalently bound 2-NT-derived material were always 2-6 times higher than those of 3- or 4-NT-derived material. When DNA was isolated from livers of rats given the mononitrotoluenes 12 h previously, only 2-NT was observed to covalently bind at concentrations above the limits of detection of the assay. The covalent binding of 2-NT, but not that of 3- or 4-NT, to both total hepatic macromolecules and DNA was markedly decreased by prior administration of either PCP or DCNP. Covalent binding to hepatic DNA was decreased by greater than 96%. The results of this study correlate well with studies which have demonstrated that 2-NT, but not 3- or 4-NT, induces DNA excision repair. Furthermore, they suggest that 2-NT, like the hepatocarcinogen 2,6-dinitrotoluene, requires the action of sulfotransferase for its conversion to a species capable of covalently binding to hepatic DNA. 相似文献
8.
The Penicillium strain Bi 7/2 able to grow on phenol as sole source of carbon and energy was isolated from a contaminated soil in Bitterfeld (East Germany). The strain is adapted to high phenol concentrations. Spores germinated still at a phenol concentration of 1.5 g/l. Phenol is degraded by the ortho-pathway with catechol as first intermediary product. The Penicillium strain metabolizes 4-, 3- and 2-chlorophenol with decreasing rates with phenol or glucose as cosubstrate. In the case of 4-chlorophenol 4-chlorocatechol was detected as intermediary product, further degraded as indicated by release of about 35% of the bound chlorine of the aromatic molecule. The strain also cometabolically metabolizes 4-, 3- and 2-nitrophenol. The final product of 3- and 4-nitrophenol is 4-nitrocatechol. 相似文献
9.
Suitability of Recombinant Escherichia coli and Pseudomonas putida Strains for Selective Biotransformation of m-Nitrotoluene by Xylene Monooxygenase 总被引:1,自引:0,他引:1
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Escherichia coli JM101(pSPZ3), containing xylene monooxygenase (XMO) from Pseudomonas putida mt-2, catalyzes specific oxidations and reductions of m-nitrotoluene and derivatives thereof. In addition to reactions catalyzed by XMO, we focused on biotransformations by native enzymes of the E. coli host and their effect on overall biocatalyst performance. While m-nitrotoluene was consecutively oxygenated to m-nitrobenzyl alcohol, m-nitrobenzaldehyde, and m-nitrobenzoic acid by XMO, the oxidation was counteracted by an alcohol dehydrogenase(s) from the E. coli host, which reduced m-nitrobenzaldehyde to m-nitrobenzyl alcohol. Furthermore, the enzymatic background of the host reduced the nitro groups of the reactants resulting in the formation of aromatic amines, which were shown to effectively inhibit XMO in a reversible fashion. Host-intrinsic oxidoreductases and their reaction products had a major effect on the activity of XMO during biocatalysis of m-nitrotoluene. P. putida DOT-T1E and P. putida PpS81 were compared to E. coli JM101 as alternative hosts for XMO. These promising strains contained an additional dehydrogenase that oxidized m-nitrobenzaldehyde to the corresponding acid but catalyzed the formation of XMO-inhibiting aromatic amines at a significantly lower level than E. coli JM101. 相似文献
10.
A strain of Pseudomonas sp. was isolated from nitrobenzene-contaminated soil and groundwater on 2-nitrotoluene as the sole source of carbon, energy, and nitrogen. Bacterial cells growing on 2-nitrotoluene released nitrite into the growth medium. The isolate also grew on 3-methylcatechol, 4-methylcatechol, and catechol. 2-Nitrotoluene, 3-methylcatechol, and catechol stimulated oxygen consumption by intact cells regardless of the growth substrate. Crude extracts from the isolate contained catechol 2,3-dioxygenase and 2-hydroxy-6-oxohepta-2,4-dienoate hydrolase activity. The results suggest that 2-nitrotoluene is subject to initial attack by a dioxygenase enzyme that forms 3-methylcatechol with concomitant release of nitrite. The 3-methylcatechol is subsequently degraded via the meta ring fission pathway. 相似文献
11.
Biodegradation of 3-Nitrobenzoate by <Emphasis Type="Italic">Bacillus flexus</Emphasis> strain XJU-4
Sikandar I. Mulla T. P. Manjunatha Robertcyril S. Hoskeri Preeti N. Tallur Harichandra Z. Ninnekar 《World journal of microbiology & biotechnology》2011,27(7):1587-1592
Bacillus flexus strain XJU-4 utilized 3-nitrobenzoate at 12 mM as a sole source of carbon and energy. This strain also utilized 4-nitrobenzoate,
2-nitrotoluene and nitrobenzene as growth substrates. The optimum conditions for degradation of 3-nitrobenzoate by the organism
were found to be at pH 7.0 and temperature 30°C. Metabolite analysis, growth and enzymatic studies have revealed that the
organism degraded 3-nitrobenzoate by oxidative mechanism through protocatechuate with the release of nitrite. The cells grown
on 3-nitrobenzoate utilized protocatechuate but not 3-hydroxybenzoate, 3-aminobenzoate, 4-hydroxy-3-nitrobenzoate and 4-nitrocatechol.
The cell-free extract of Bacillus flexus strain XJU-4 grown on 3-nitrobenzoate contained the activity of protocatechuate 2,3-dioxygenase, which suggest that protocatechuate
was further degraded by a novel 2,3-dioxygenative meta-cleavage pathway. 相似文献
12.
Sikandar I. Mulla Robertcyril S. Hoskeri Yogesh S. Shouche Harichandra Z. Ninnekar 《Biodegradation》2011,22(1):95-102
A bacterial consortium capable of degrading nitroaromatic compounds was isolated from pesticide-contaminated soil samples
by selective enrichment on 2-nitrotoluene as a sole source of carbon and energy. The three different bacterial isolates obtained
from bacterial consortium were identified as Bacillus sp. (A and C), Bacillus flexus (B) and Micrococcus sp. (D) on the basis of their morphological and biochemical characteristics and by phylogenetic analysis based on 16S rRNA
gene sequences. The pathway for the degradation of 2-nitrotoluene by Micrococcus sp. strain SMN-1 was elucidated by the isolation and identification of metabolites, growth and enzymatic studies. The organism
degraded 2-nitrotoluene through 3-methylcatechol by a meta-cleavage pathway, with release of nitrite. 相似文献
13.
Oxidation of nitrotoluenes by toluene dioxygenase: evidence for a monooxygenase reaction. 总被引:6,自引:0,他引:6
J B Robertson J C Spain J D Haddock D T Gibson 《Applied and environmental microbiology》1992,58(8):2643-2648
Pseudomonas putida F1 and Pseudomonas sp. strain JS150 initiate toluene degradation by incorporating molecular oxygen into the aromatic nucleus to form cis-1,2-dihydroxy-3-methylcyclohexa-3,5-diene. When toluene-grown cells were incubated with 2- and 3-nitrotoluene, the major products identified were 2- and 3-nitrobenzyl alcohol, respectively. The same cells oxidized 4-nitrotoluene to 2-methyl-5-nitrophenol and 3-methyl-6-nitrocatechol. Escherichia coli JM109(pDTG601), which contains the toluene dioxygenase genes from P. putida F1 under the control of the tac promoter, oxidized the isomeric nitrotoluenes to the same metabolites as those formed by P. putida F1 and Pseudomonas sp. strain JS150. These results extend the range of substrates known to be oxidized by this versatile enzyme and demonstrate for the first time that toluene dioxygenase can oxidize an aromatic methyl substituent. 相似文献
14.
Oxidation of nitrotoluenes by toluene dioxygenase: evidence for a monooxygenase reaction. 总被引:10,自引:5,他引:5
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Pseudomonas putida F1 and Pseudomonas sp. strain JS150 initiate toluene degradation by incorporating molecular oxygen into the aromatic nucleus to form cis-1,2-dihydroxy-3-methylcyclohexa-3,5-diene. When toluene-grown cells were incubated with 2- and 3-nitrotoluene, the major products identified were 2- and 3-nitrobenzyl alcohol, respectively. The same cells oxidized 4-nitrotoluene to 2-methyl-5-nitrophenol and 3-methyl-6-nitrocatechol. Escherichia coli JM109(pDTG601), which contains the toluene dioxygenase genes from P. putida F1 under the control of the tac promoter, oxidized the isomeric nitrotoluenes to the same metabolites as those formed by P. putida F1 and Pseudomonas sp. strain JS150. These results extend the range of substrates known to be oxidized by this versatile enzyme and demonstrate for the first time that toluene dioxygenase can oxidize an aromatic methyl substituent. 相似文献
15.
ntn Genes Determining the Early Steps in the Divergent Catabolism of 4-Nitrotoluene and Toluene in Pseudomonas sp. Strain TW3 总被引:2,自引:0,他引:2
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Pseudomonas sp. strain TW3 is able to oxidatively metabolize 4-nitrotoluene and toluene via a route analogous to the upper pathway of the TOL plasmids. We report the sequence and organization of five genes, ntnWCMAB*, which are very similar to and in the same order as the xyl operon of TOL plasmid pWW0 and present evidence that they encode enzymes which are expressed during growth on both 4-nitrotoluene and toluene and are responsible for their oxidation to 4-nitrobenzoate and benzoate, respectively. These genes encode an alcohol dehydrogenase homolog (ntnW), an NAD+-linked benzaldehyde dehydrogenase (ntnC), a two-gene toluene monooxygenase (ntnMA), and part of a benzyl alcohol dehydrogenase (ntnB*), which have 84 to 99% identity at the nucleotide and amino acid levels with the corresponding xylWCMAB genes. The xylB homolog on the TW3 genome (ntnB*) appears to be a pseudogene and is interrupted by a piece of DNA which destroys its functional open reading frame, implicating an additional and as-yet-unidentified benzyl alcohol dehydrogenase gene in this pathway. This conforms with the observation that the benzyl alcohol dehydrogenase expressed during growth on 4-nitrotoluene and toluene differs significantly from the XylB protein, requiring assay via dye-linked electron transfer rather than through a nicotinamide cofactor. The further catabolism of 4-nitrobenzoate and benzoate diverges in that the former enters the hydroxylaminobenzoate pathway as previously reported, while the latter is further metabolized via the β-ketoadipate pathway. 相似文献
16.
From anaerobic digestor sludge of a waste water treatment plant, a gram-negative, strictly anaerobic sulfate-reducing bacterium was isolated with acetone as sole organic substrate. The bacterium was characterized as a new species, Desulfococcus biacutus. The strain grew with acetone with doubling times of 72 h to 120 h; the growth yield was 12.0 (±2.1) g · [mol acetone]-1. Acetone was oxidized completely, and no isopropanol was formed. In labelling studies with 14CO2, cell lipids (including approx. 50% PHB) of acetone-grown cells became labelled 7 times as high as those of 3-hydroxy-buyrate-grown cells. Enzyme studies indicated that acetone was degraded via acetoacetyl-CoA, and that acetone was channeled into the intermediary metabolism after condensation with carbon dioxide to a C4-compound, possibly free acetoacetate. Acetoacetyl-CoA is cleaved by a thiolase reaction to acetyl-CoA which is completely oxidized through the carbon monoxide dehydrogenase pathway. Strain KMRActS was deposited with the Deutsche Sammlung von Mikroorganismen, Braunschweig, under the number DSM 5651. 相似文献
17.
Cloning of bacterial genes specifying degradation of 4-chlorobiphenyl from Pseudomonas putida OU83 总被引:3,自引:0,他引:3
Genes capable of 4-chlorobiphenyl (4-CBP) degradation were cloned from 4-CBP-degrading Pseudomonas putida OU83 by using a genomic library which was constructed in the broad-host-range cosmid vector pCP13. P. putida AC812 containing chimeric cosmid-expressing enzymes involved in the 4-CBP degradation pathway were identified by detecting 3-phenylcatechol dioxygenase activity (3-PDA). Chimeric cosmid clones pOH83, pOH84, pOH85, pOH87, and pOH88 positive for 3-PDA grew in synthetic basal medium containing 4-CBP (5 mM) as a carbon source. Restriction digestion analysis of recombinant cosmids showed DNA inserts ranging from 6 to 30 kilobase pairs. Southern hybridization data revealed that the cloned DNA inserts originated from strain OU83. Gas chromatography-mass spectrometry analysis of the metabolites of P. putida AC812(pOH88) incubated with 4-CBP and 4'-chloro-3-phenylcatechol showed the formation of 4-chlorobenzoic acid and benzoic acid. These results demonstrate that the cloned DNA fragments contain genes encoding for chlorobiphenyl dioxygenase (cbpA), dihydrodiol dehydrogenase (cbpB), 4'-chloro-3-phenylcatechol dioxygenase (cbpC), a meta-cleavage compound (a chloro derivative of 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate) hydrolase (cbpD), and a new dechlorinating activity (dcpE). The location of the cbpC gene specifying 3-PDA was determined by subcloning an EcoRI DNA fragment (9.8 kilobase pairs) of pOH88 in plasmid vector pUC19. The cloned gene encoding 3-PDA was expressed in Escherichia coli HB101 and had substrate specificity only for 3-phenylcatechol and 4'-chloro-3-phenylcatechol. 相似文献
18.
Cloning of bacterial genes specifying degradation of 4-chlorobiphenyl from Pseudomonas putida OU83. 总被引:10,自引:6,他引:4
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Genes capable of 4-chlorobiphenyl (4-CBP) degradation were cloned from 4-CBP-degrading Pseudomonas putida OU83 by using a genomic library which was constructed in the broad-host-range cosmid vector pCP13. P. putida AC812 containing chimeric cosmid-expressing enzymes involved in the 4-CBP degradation pathway were identified by detecting 3-phenylcatechol dioxygenase activity (3-PDA). Chimeric cosmid clones pOH83, pOH84, pOH85, pOH87, and pOH88 positive for 3-PDA grew in synthetic basal medium containing 4-CBP (5 mM) as a carbon source. Restriction digestion analysis of recombinant cosmids showed DNA inserts ranging from 6 to 30 kilobase pairs. Southern hybridization data revealed that the cloned DNA inserts originated from strain OU83. Gas chromatography-mass spectrometry analysis of the metabolites of P. putida AC812(pOH88) incubated with 4-CBP and 4'-chloro-3-phenylcatechol showed the formation of 4-chlorobenzoic acid and benzoic acid. These results demonstrate that the cloned DNA fragments contain genes encoding for chlorobiphenyl dioxygenase (cbpA), dihydrodiol dehydrogenase (cbpB), 4'-chloro-3-phenylcatechol dioxygenase (cbpC), a meta-cleavage compound (a chloro derivative of 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate) hydrolase (cbpD), and a new dechlorinating activity (dcpE). The location of the cbpC gene specifying 3-PDA was determined by subcloning an EcoRI DNA fragment (9.8 kilobase pairs) of pOH88 in plasmid vector pUC19. The cloned gene encoding 3-PDA was expressed in Escherichia coli HB101 and had substrate specificity only for 3-phenylcatechol and 4'-chloro-3-phenylcatechol. 相似文献
19.
A strain of Pseudomonas putida (2NP8) capable of growing on both 2-nitrophenol and 3-nitrophenol, but not on nitrobenzene (NB), was isolated from municipal activated sludge. 2-Nitrophenol was degraded by this strain with production of nitrite. Degradation of 3-nitrophenol resulted in the formation of ammonia. Cells grown on 2-nitrophenol did not degrade nitrobenzene. A specific nitrobenzene degradation activity was induced by 3-nitrophenol. Ammonia, nitrosobenzene, and hydroxylaminobenzene have been detected as metabolites of nitrobenzene degradation by cells grown in the presence of 3-nitrophenol. These results indicated a NB cometabolism mediated by 3-nitrophenol nitroreductase. 相似文献
20.
Deepak Singh Archana Kumari S. Ramaswamy Gurunath Ramanathan 《Biochemical and biophysical research communications》2014
3-Nitotoluene dioxygenase (3-NTDO) is the first enzyme in the degradation pathway of 3-nitrotoluene (3-NT) by Diaphorobacter sp. strain DS2. The complete gene sequences of 3-NTDO were PCR amplified from genomic DNA of Diaphorobacter sp., cloned, sequenced and expressed. The 3-NTDO gene revealed a multi component structure having a reductase, a ferredoxin and two oxygenase subunits. Clones expressing the different subunits were constructed in pET21a expression vector system and overexpressed in E. coli BL21(DE3) host. Each subunit was individually purified separately to homogeneity. The active recombinant enzyme was reconstituted in vitro by mixing all three purified subunits. The reconstituted recombinant enzyme could catalyse biotransformations on a variety of organic aromatics. 相似文献