Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Chlorophenols”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,009 records · Page 56Linked to original sources
PubMed2003

Efficient degradation of 2,4,6-Trichlorophenol requires a set of catabolic genes related to tcp genes from Ralstonia eutropha JMP134(pJP4).

2,4,6-Trichlorophenol (2,4,6-TCP) is a hazardous pollutant. Several aerobic bacteria are known to degrade this compound. One of these, Ralstonia eutropha JMP134(pJP4), a well-known, versatile chloroaromatic compound degrader, is able to grow in 2,4,6-TCP by converting it to 2,6-dichlorohydroquinone, 6-chlorohydroxyquinol, 2-chloromaleylacetate, maleylacetate, and beta-ketoadipate. Three enzyme activities encoded by tcp genes, 2,4,6-TCP monooxygenase (tcpA), 6-chlorohydroxyquinol 1,2-dioxygenase (tcpC), and maleylacetate reductase (tcpD), are involved in this catabolic pathway. Here we provide evidence that all these tcp genes are clustered in the R. eutropha JMP134(pJP4) chromosome, forming the putative catabolic operon tcpRXABCYD. We studied the presence of tcp-like gene sequences in several other 2,4,6-TCP-degrading bacterial strains and found two types of strains. One type includes strains belonging to the Ralstonia genus and possessing a set of tcp-like genes, which efficiently degrade 2,4,6-TCP and therefore grow in liquid cultures containing this chlorophenol as a sole carbon source. The other type includes strains belonging to the genera Pseudomonas, Sphingomonas, or Sphingopixis, which do not have tcp-like gene sequences and degrade this pollutant less efficiently and which therefore grow only as small colonies on plates with 2,4,6-TCP. Other than strain JMP134, none of the bacterial strains whose genomes have been sequenced possesses a full set of tcp-like gene sequences.

Bacterial Proteins↗
PubMed2003

Characterization of Fe(III) reduction by chlororespiring Anaeromyxobacter dehalogenans.

Anaeromyxobacter dehalogenans strain 2CP-C has been shown to grow by coupling the oxidation of acetate to the reduction of ortho-substituted halophenols, oxygen, nitrate, nitrite, or fumarate. In this study, strain 2CP-C was also found to grow by coupling Fe(III) reduction to the oxidation of acetate, making it one of the few isolates capable of growth by both metal reduction and chlororespiration. Doubling times for growth of 9.2 and 10.2 h were determined for Fe(III) and 2-chlorophenol reduction, respectively. These were determined by using the rate of [(14)C]acetate uptake into biomass. Fe(III) compounds used by strain 2CP-C include ferric citrate, ferric pyrophosphate, and amorphous ferric oxyhydroxide. The addition of the humic acid analog anthraquinone 2,6-disulfonate (AQDS) increased the reduction rate of amorphous ferric iron oxide, suggesting AQDS was used as an electron shuttle by strain 2CP-C. The addition of chloramphenicol to fumarate-grown cells did not inhibit Fe(III) reduction, indicating that the latter activity is constitutive. In contrast, the addition of chloramphenicol inhibited dechlorination activity, indicating that chlororespiration is inducible. The presence of insoluble Fe(III) oxyhydroxide did not significantly affect dechlorination, whereas the presence of soluble ferric pyrophosphate inhibited dechlorination. With its ability to respire chlorinated organic compounds and metals such as Fe(III), strain 2CP-C is a promising model organism for the study of the interaction of these potentially competing processes in contaminated environments.

Acetic Acid↗
PubMed2004

Purification, cloning, and sequencing of a 3,5-dichlorophenol reductive dehalogenase from Desulfitobacterium frappieri PCP-1.

A membrane-associated 3,5-dichlorophenol reductive dehalogenase was isolated from Desulfitobacterium frappieri PCP-1. The highest dehalogenase activity was observed with the biomass cultured at 22 degrees C, compared to 30 and 37 degrees C, where the cell suspensions were 2.2 and 9.6 times less active, respectively. The reductive dehalogenase was purified 12.7-fold to apparent homogeneity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a single band with an apparent molecular mass of 57 kDa. Its dechlorinating activity was not inhibited by sulfate and nitrate but was completely inhibited by 2.5 mM sulfite and 10 mM KCN. A mixture of iodopropane and titanium citrate caused a light-reversible inhibition of the dechlorinating activities, suggesting the involvement of a corrinoid cofactor. Several polychlorophenols were dechlorinated at the meta and para positions. The apparent K(m) for 3,5-dicholorophenol was 49.3 +/- 3.1 microM at a methyl viologen concentration of 2 mM. Six internal tryptic peptides were sequenced by mass spectrometry. One open reading frame (ORF) was found in the Desulfitobacterium hafniense genome containing these peptide sequences. This ORF corresponds to a gene coding for a CprA-type reductive dehalogenase. The corresponding ORF (named cprA5) in D. frappieri PCP-1 was cloned and sequenced. The cprA5 gene codes for a 548-amino-acid protein that contains a twin-arginine-type signal for secretion. The gene product has a cobalamin binding site motif and two iron-sulfur binding motifs and shows 66% identity (76 to 77% similarity) with some tetrachloroethene reductive dehalogenases. This is the first CprA-type reductive dehalogenase that can dechlorinate chlorophenols at the meta and para positions.

Amino Acid Sequence↗
PubMed2006

Uranium(VI) reduction by Anaeromyxobacter dehalogenans strain 2CP-C.

Previous studies demonstrated growth of Anaeromyxobacter dehalogenans strain 2CP-C with acetate or hydrogen as the electron donor and Fe(III), nitrate, nitrite, fumarate, oxygen, or ortho-substituted halophenols as electron acceptors. In this study, we explored and characterized U(VI) reduction by strain 2CP-C. Cell suspensions of fumarate-grown 2CP-C cells reduced U(VI) to U(IV). More-detailed growth studies demonstrated that hydrogen was the required electron donor for U(VI) reduction and could not be replaced by acetate. The addition of nitrate to U(VI)-reducing cultures resulted in a transitory increase in U(VI) concentration, apparently caused by the reoxidation of reduced U(IV), but U(VI) reduction resumed following the consumption of N-oxyanions. Inhibition of U(VI) reduction occurred in cultures amended with Fe(III) citrate, or citrate. In the presence of amorphous Fe(III) oxide, U(VI) reduction proceeded to completion but the U(VI) reduction rates decreased threefold compared to control cultures. Fumarate and 2-chlorophenol had no inhibitory effects on U(VI) reduction, and both electron acceptors were consumed concomitantly with U(VI). Since cocontaminants (e.g., nitrate, halogenated compounds) and bioavailable ferric iron are often encountered at uranium-impacted sites, the metabolic versatility makes Anaeromyxobacter dehalogenans a promising model organism for studying the complex interaction of multiple electron acceptors in U(VI) reduction and immobilization.

Chlorophenols↗
PubMed1987

Dechlorination and para-hydroxylation of polychlorinated phenols by Rhodococcus chlorophenolicus.

In this paper we show that a polychlorophenol degrader Rhodococcus chlorophenolicus PCP-I initially attacked polychlorinated phenols (pentachlorophenol, 2,3,4,5-, 2,3,4,6-, and 2,3,5,6-tetrachlorophenol, and 2,3,5- and 2,3,6-trichlorophenol) by tetra- or trichlorohydroquinone-producing para-hydroxylation. The novel hydroxyl group was set in position 4, whether or not a substrate had chlorine substituent in this position. The hydroxyl was in each case derived from water molecules, as was shown by following the incorporation of oxygen from H2(18)O into the reaction products. Nevertheless, the para-hydroxylation reaction required the presence of molecular oxygen, whereas further metabolism of the reaction product, tetrachlorohydroquinone, proceeded also in anaerobiosis. All polychlorinated phenols were readily transformed at 41 degrees C, but none were transformed at 44 degrees C. In contrast to this, tetrachlorohydroquinone was metabolized at a high rate at 50 degrees C, but was not metabolized at 55 degrees C. Polychlorinated phenols were specific inducers of the para-hydroxylating enzymes; para-hydroxylated reaction products did not induce these enzymes. On the other hand, the degradation of tri- and tetrachlorohydroquinone was induced by any of the chlorophenols and also by hydroquinones.

Aerobiosis↗
PubMed1989

Enzymatic dehalogenation of pentachlorophenol by extracts from Arthrobacter sp. strain ATCC 33790.

Arthrobacter sp. strain ATCC 33790 was grown with pentachlorophenol (PCP) as the sole source of carbon and energy. Crude extracts, which were prepared by disruption of the bacteria with a French pressure cell, showed no dehalogenating activity with PCP as the substrate. After sucrose density ultracentrifugation of the crude extract at 145,000 x g, various layers were found in the gradient. One yellow layer showed enzymatic conversion of PCP. One chloride ion was released per molecule of PCP. The product of the enzymatic conversion was tetrachlorohydroquinone. NADPH and oxygen were essential for this reaction. EDTA stimulated the enzymatic activity by 67%. The optimum pH for the enzyme activity was 7.5, and the temperature optimum was 25 degrees C. Enzymatic activity was also detected with 2,4,5-trichlorophenol, 2,3,4-trichlorophenol, 2,4,6-trichlorophenol, and 2,3,4,5-tetrachlorophenol as substrates, whereas 3,4,5-trichlorophenol, 2,4-dichlorophenol, 3,4-dichlorophenol, and 4-chlorophenol did not serve as substrates.

Arthrobacter↗
PubMed1995

Characterization of muconate and chloromuconate cycloisomerase from Rhodococcus erythropolis 1CP: indications for functionally convergent evolution among bacterial cycloisomerases.

Muconate cycloisomerase (EC 5.5.1.1) and chloromuconate cycloisomerase (EC 5.5.1.7) were purified from extracts of Rhodococcus erythropolis 1CP cells grown with benzoate or 4-chlorophenol, respectively. Both enzymes discriminated between the two possible directions of 2-chloro-cis, cis-muconate cycloisomerization and converted this substrate to 5-chloromuconolactone as the only product. In contrast to chloromuconate cycloisomerases of gram-negative bacteria, the corresponding R. erythropolis enzyme is unable to catalyze elimination of chloride from (+)-5-chloromuconolactone. Moreover, in being unable to convert (+)-2-chloromuconolactone, the two cycloisomerases of R. erythropolis 1CP differ significantly from the known muconate and chloromuconate cycloisomerases of gram-negative strains. The catalytic properties indicate that efficient cycloisomerization of 3-chloro- and 2,4-dichloro-cis,cis-muconate might have evolved independently among gram-positive and gram-negative bacteria.

4-Butyrolactone↗
PubMed1997

Purification and characterization of 2,4,6-trichlorophenol-4-monooxygenase, a dehalogenating enzyme from Azotobacter sp. strain GP1.

The enzyme which catalyzes the dehalogenation of 2,4,6-trichlorophenol (TCP) was purified to apparent homogeneity from an extract of TCP-induced cells of Azotobacter sp. strain GP1. The initial step of TCP degradation in this bacterium is inducible by TCP; no activity was found in succinate-grown cells or in phenol-induced cells. NADH, flavin adenine dinucleotide, and O2 are required as cofactors. As reaction products, 2,6-dichlorohydroquinone and Cl- ions were identified. Studies of the stoichiometry revealed the consumption of 2 mol of NADH plus 1 mol of O2 per mol of TCP and the formation of 1 mol of Cl- ions. No evidence for membrane association or for a multicomponent system was obtained. Molecular masses of 240 kDa for the native enzyme and 60 kDa for the subunit were determined, indicating a homotetrameric structure. Cross-linking studies with dimethylsuberimidate were consistent with this finding. TCP was the best substrate for 2,4,6-trichlorophenol-4-monooxygenase (TCP-4-monooxygenase). The majority of other chlorophenols converted by the enzyme bear a chloro substituent in the 4-position. 2,6-Dichlorophenol, also accepted as a substrate, was hydroxylated in the 4-position to 2,6-dichlorohydroquinone in a nondehalogenating reaction. NADH and O2 were consumed by the pure enzyme also in the absence of TCP with simultaneous production of H2O2. The NH2-terminal amino acid sequence of TCP-4-monooxygenase from Azotobacter sp. strain GP1 revealed complete identity with the nucleotide-derived sequence from the analogous enzyme from Pseudomonas pickettii and a high degree of homology with two nondehalogenating monooxygenases. The similarity in enzyme properties and the possible evolutionary relatedness of dehalogenating and nondehalogenating monooxygenases are discussed.

Amino Acid Sequence↗
PubMed1964

MICROBIAL METABOLISM OF AROMATIC COMPOUNDS. I. DECOMPOSITION OF PHENOLIC COMPOUNDS AND AROMATIC HYDROCARBONS BY PHENOL-ADAPTED BACTERIA.

Tabak, Henry H. (Robert A. Taft Sanitary Engineering Center, Cincinnati, Ohio), Cecil W. Chambers, and Paul W. Kabler. Microbial metabolism of aromatic carbon compounds. I. Decomposition of phenolic compounds and aromatic hydrocarbons by phenol-adapted bacteria. J. Bacteriol. 87:910-919. 1964.-Bacteria from soil and related environments were selected or adapted to metabolize phenol, hydroxy phenols, nitrophenols, chlorophenols, methylphenols, alkylphenols, and arylphenols when cultured in mineral salts media with the specific substrate as the sole source of carbon. A phenol-adapted culture (substrate-induced enzyme synthesis proven) was challenged in respirometric tests with 104 related compounds; probable significant oxidative activity occurred with 65. Dihydric phenols were generally oxidized; trihydric phenols were not. Cresols and dimethylphenols were oxidized; adding a chloro group increased resistance. Benzoic and hydroxybenzoic acids were oxidized; sulfonated, methoxylated, nitro, and chlorobenzoic acids were not; m-toluic acid was utilized but not the o- and p-isomers. Benzaldehyde and p-hydroxybenzaldehyde were oxidized. In general, nitro- and chloro-substituted compounds and the benzenes were difficult to oxidize.

Bacteria↗
PubMed2006

Specificity of catechol ortho-cleavage during para-toluate degradation by Rhodococcus opacus 1cp.

Degradation of para-toluate by Rhodococcus opacus 1cp was investigated. Activities of the key enzymes of this process, catechol 1,2-dioxygenase and muconate cycloisomerase, are detected in this microorganism. Growth on p-toluate was accompanied by induction of two catechol 1,2-dioxygenases. The substrate specificity and physicochemical properties of one enzyme are identical to those of chlorocatechol 1,2-dioxygenase; induction of the latter enzyme was observed during R. opacus 1cp growth on 4-chlorophenol. The other enzyme isolated from the biomass grown on p-toluate exhibited lower rate of chlorinated substrate cleavage compared to the catechol substrate. However, this enzyme is not identical to the catechol 1,2-dioxygenase cloned in this strain within the benzoate catabolism operon. This supports the hypothesis on the existence of multiple forms of dioxygenases as adaptive reactions of microorganisms in response to environmental stress.

Adaptation, Physiological↗
PubMedDate not supplied

Evaluation of beta-galactosidase activity in tissue in the presence of blood.

The reporter gene for beta-galactosidase is frequently used to determine the efficiency of gene transfer in arteries. However, blood is often present in arterial explants and may compromise the results by the presence of hemoglobin. The light absorption of hemoglobin is similar to the absorption of several colorimetric products of the commonly used beta-galactosidase substrates, including o-nitrophenyl-beta-D-galactopyranoside (ONPG) and chlorophenol red galactopyranoside (CPRG). This may result in false-positive measurements of beta-galactosidase enzyme activity. The aim of this investigation was to determine the most appropriate method for quantification of beta-galactosidase activity in the presence of blood. Colorimetric substrates (ONPG, CPRG) or the chemiluminescent Galacton-Plus substrate were used, and light absorption was measured at different concentrations of erythrocyte extract. Among the beta-galactosidase substrates tested, CPRG was the most appropriate, allowing detection of enzyme activity at concentrations as low as 0.05 mU, independent of blood contamination. Addition of reducer stabilized enzyme activity for at least 5 h. Endogenous beta-galactosidase activity was evaluated and used to correct results. CPRG substrate, in combination with the reducer agent mercaptoethanol, was found to be the optimal reagent for quantifying beta-galactosidase activity in the presence of blood after nonviral in vivo reporter gene transfection, even with a relatively low transfer efficiency.

Animals↗
PubMed1987

Pentachlorophenol and hexachlorobenzene in serum and urine of the population of Barcelona.

1 Urinary chlorophenols of the general population of Barcelona, Spain were determined. Pentachlorophenol (PCP: 25.0 +/- 3.9 ng/ml; mean +/- s.e.m., n = 50) and tetrachlorophenol (TCP: 6.2 +/- 1.6 ng/ml; mean +/- s.e.m., n = 25) were found in all samples. 2 Pentachlorophenol and hexachlorobenzene were also determined in serum. Both were present in all samples (PCP: 21.9 +/- 1.9 ng/ml; HCB: 11.1 +/- 1.1 ng/ml; mean +/- s.e.m., n = 100). Their concentrations do not show any correlation, suggesting no metabolic relation between them.

Chlorobenzenes↗
PubMed1989

The anti-inflammatory effects of phenolic dental medicaments as determined by mouse ear edema assay.

The anti-inflammatory effects of phenolic dental medicaments were evaluated by mouse ear edema assay. p-Chlorophenol (PCP) inhibited edema when applied topically in dosages of 0.2 and 0.5 mg per site at 15 min before or 1.0 and 2.0 mg per site at 60 min after the application of croton oil. The inhibitory effects were also noted with eugenol, guaiacol, o-cresol, phenol and orally administered indomethacin (10 mg/kg). The involvement of the effects on prostaglandin biosynthesis in the anti-inflammatory effects of these compounds is discussed.

Animals↗
PubMed2004

Pseudomonas putida NCTC 10936 balances membrane fluidity in response to physical and chemical stress by changing the saturation degree and the trans/cis ratio of fatty acids.

This study explored the capability of Pseudomonas putida NCTC 10936 to maintain homeoviscosity after changing the growth temperature, incubating resting cells at different temperatures or at a constant temperature in the presence of 4-chlorophenol (4-CP). After raising the growth temperature from 20 to either 30 or 35 degrees C, the degree of saturation of the organism's fatty acids increased and the ratio of trans to cis unsaturated fatty acids decreased somewhat. In contrast, after the incubation temperature of resting cells was raised (grown at 30 degrees C) from 20 to 30 or 35 degrees C the degree of saturation of the fatty acids remained nearly constant, while the ratio of trans to cis unsaturated fatty acids increased. Incubating resting cells (grown at 30 degrees C) at 20 degrees C in the presence of 4-CP again caused no major changes in the degree of saturation, but cis to trans conversion of unsaturated fatty acids was induced, with a corresponding increase in the trans/cis ratios. Increases in both the saturation degree of the fatty acids and the trans/cis ratio of the unsaturated fatty acids correlated with increases in the fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene intercalated in the bilayers of liposomes prepared from the cells of P. putida NCTC 10936. Electron transport phosphorylation (ETP) could be stabilized by adaptive adjustments in the fluidity of the cytoplasmic membrane mediated by changes in fatty acid composition such as those observed. Whether changes in the degree of saturation or in the trans/cis ratio are more effective can be decided by studying P. putida NCTC 10936.

Anisotropy↗
PubMed1992

[Amounts of urinary metabolites of p-chloroaniline and their half lives in a patient with acute poisoning].

The aim of this study was to elucidate the time courses of amounts of urinary p-chloroaniline (p-CA) metabolites during acute poisoning and to establish a suitable method for biological monitoring of exposure to p-CA. Urinary p-CA metabolites which were previously identified in a patient with acute p-CA poisoning were determined quantitatively over time during admission of a patient by high-performance liquid chromatography (HPLC) and by the colorimetric method of diazo-positive metabolites (DPM). The data of urinary excretion of each p-CA metabolite were fitted to two-compartment model of pharmacokinetics. Major urinary metabolites of p-CA were conjugated p-CA and conjugated 2-amino-5-chlorophenol (2-A-5-CP), and the detected amounts of 2,4-dichloroaniline (2,4-DCA) and free p-CA were small. During the rapid phase for the disappearance of each metabolite, half lives of p-CA, 2-A-5-CP and 2,4-DCA were 2.4, 1.7 and 1.7 h, respectively, and during the slow phase, they were 4.5, 3.3 and 3.8 h, respectively. Urinary p-CA occupied about 62% of the total metabolites detected in the urine, 2-A-5-CP about 36%, and 2,4-DCA about 1%. 2-A-5-CP and p-CA were detected in the urine of the patient obtained on days 3 and 4, respectively, after the poisoning, but the amount of DPM after the second day of the poisoning was in the range of that of non-exposed persons.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed2006

Pyrolusite (beta-MnO2)-mediated, near dry-phase oxidation of 2,4,6-trichlorophenol.

The pyrolusite (beta-MnO2)-mediated oxidation of 2,4,6-trichlorophenol (TCP) under nonaqueous conditions was investigated to assess the potential for abiotic transformations of chlorophenols and their transformation pathways when they are released to soils and the vadose zone. Lower rates of TCP oxidation were found at lower relative humidities, but the rates were still relatively high under near-dry conditions, with 86% of the TCP transformed within 24 h at less than 2% relative humidity. The rates of TCP transformation and soluble manganese formation at less than 2% relative humidity were not affected by atmospheric oxygen content. The manganese oxide-mediated oxidation of TCP resulted in the formation of 2,6-dichloro-1,4-benzoquinone and dimers, including polychlorinated phenoxyphenols and at least one tetrachlorodibenzo-p-dioxin. The products are consistent with the proposed mechanism in which some of the TCP is transformed into trichlorophenoxy radicals that attack TCP and its transformation products. The present results demonstrate that naturally occurring manganese oxides have the potential to oxidize industrial compounds such as TCP; however, the transformation products may be more toxic and persistent than the parent compound.

Chlorophenols↗
PubMed2002

Application of a pentafluorobenzyl bromide derivatization method in gas chromatography/mass spectrometry of trace levels of halogenated phenols in air, water and sediment samples.

An analytical method using pentafluorobenzyl bromide (PFBB) derivatization and gas chromatography/mass spectrometry (GC/MS) has been applied to identify and quantify chloro-, bromo- and dichlorophenols in air, water and sediment samples. Phenols in air sample were collected with a PS-2 Sep-PAK cartridge, and eluted with 2-propanol. For water and sediment samples, liquid-liquid extraction with dichloromethane was carried out, and the solvent was exchanged to 2-propanol. The phenols in the solution reacted with PFBB to form the corresponding pentafluorobenzyl esters. After extracting the derivatives into hexane, the determination was carried out by GC/MS with selected-ion monitoring. The detection limits of phenols in air, water and sediment were 0.0033 - 0.0073 microg/m3, 0.0066 - 0.0147 microg/L and 0.33 - 0.73 microg/kg, respectively. More than 90% recoveries of the halogenated phenols were obtained from real environmental samples spiked by the halogenated phenols. The three isomers of mono-chlorophenols were detected in sediment samples in the range of 5.2 - 9.2 microg/kg in wet weight basis.

Air↗
PubMed2003

Superheated water chromatography of phenols using poly(styrene-divinylbenzene) packings as a stationary phase.

A method for the superheated water chromatography of phenols was developed using a poly(styrene-divinylbenzene) (PSDVB) stationary phase. The stationary phase of superheated water chromatography must be stable against the attack of water. A durability test for PSDVB packings and octadecylsilyl (ODS)-silica gels indicated that PSDVB packings were stable in superheated water in the temperature range of 100-150 degrees C, whereas octadecylsilyl groups of ODS-silica gels cleaved even at 100 degrees C. The retention of phenols on the PSDVB stationary phase decreased with an elevation of the column temperature. The retention mechanism was characterized using a thermodynamic theory that has been used for describing retention in conventional RP-HPLC. The application of the present method to an environmental analysis was also demonstrated, in which a suitable separation with good peak shape was obtained for p-chlorophenol in river-water samples.

Chlorophenols↗