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PubMed2003

Solid-phase microextraction liquid chromatography/tandem mass spectrometry for the analysis of chlorophenols in environmental samples.

Liquid chromatography with atmospheric pressure chemical ionisation mass spectrometry (LC/APCI-MS), using negative ion detection in a triple quadrupole instrument, was used for the determination of chlorophenols (CPs) in environmental samples. In-source collision-induced dissociation (CID) was compared with MS/MS fragmentation. In general, less fragmentation was observed in MS/MS as compared with in-source CID, with the latter providing more intense fragment ions due to chemical ionisation. Under MS/MS conditions [M - H - HCl](-) was the main fragment ion observed for all compounds except for pentachlorophenol, which showed no fragmentation. For multiple reaction monitoring (MRM) acquisition mode, the transition from [M - H](-) to [M - H - HCl](-) was selected, leading to detection limits down to 0.3 ng injected. Direct and headspace-solid-phase microextraction (HS-SPME) were used as preconcentration procedures for the analysis of CPs in wood and in industrially contaminated soils. CPs were quantified by standard addition, which led to good reproducibility (RSD between 4 and 11%) in both SIM and MRM modes, and detection limits down to ng/g. The combination of MS/MS and in-source CID allowed confirmation of the presence of CPs in environmental samples.

Chlorophenols↗
PubMed2001

Development of a free beta-galactosidase in vitro test for the assessment of heavy metal toxicity.

The effect of heavy metals and organic compounds on the activity of the enzyme beta-galactosidase in a standardized bioassay has been evaluated, considering future applications in environmental monitoring. The tests were done using a commercial extract of a hydrolase from the eukaryote yeast Kluyveromyces lactis and o-nitrophenyl-beta-D-galactopyranoside (ONPG) as substrate. The enzyme was exposed to Cr(VI), Cd(II), Cu(II), Ni(II), Pb(II), Hg(II), phenol, sodium dodecyl sulfate, methanol and pentachlorophenol for 5, 15, 30, and 60 min. According to the results, a 15 min exposure time was considered optimum for the performance of the assay. Results of tests with metals showed IC50 values ranging between 9.25mg/L for Cd(II) and 0.015mg/L for Hg(II), with an order of sensitivity of: Cd(II) < Ni(II) < Cr(VI) = Pb(II) < Cu(II) < Hg(II). Sensitivity to organic compounds ranged from 200 to 4,000 mg/L, showing a higher specificity to heavy metals. The present in vitro free enzyme test showed a similar behavior to other tests based on beta-galactosidase such as the MetPlate. Furthermore, when compared to data from the literature on acute toxicity assays currently used in environmental assessment, test results show good agreement regarding the sensitivity to metals. After standardization, the proposed test could be used as a rapid and low-cost assay when evaluating biological effects of heavy metals in monitoring programs.

Environmental Monitoring↗
PubMed1994

Plant biochemistry of xenobiotics: isolation and characterization of a soybean O-glucosyltransferase of DDT metabolism.

The insecticide DDT is metabolized in soybean and wheat cell cultures to the acylglucoside of 2,2-bis-(4-chlorophenyl)-acetic acid (DDA) (M. Arjmand and H. Sandermann, 1985, Pesticide Biochem. Physiol. 23, 389-397). An enzyme catalyzing the conjugation reaction has been highly purified from the soluble enzyme fraction of cultured soybean cells. After the initial ammonium sulfate fractionation, quercetin and pentachlorophenol were preferentially glucosylated. In the course of 367-fold purification, DDA became the preferred substrate. The purified enzyme was unstable. A molecular weight of approximately 50 kDa was estimated for the native enzyme (gel permeation chromatography) as well as the denatured protein (sodium dodecyl sulfate-gel electrophoresis). The isoelectric point for the enzyme was near pH 4.9. Apparent Km values of about 170 microM were determined for UDP-glucose as well as DDA. The maximal velocity was 257 microkat/kg protein, corresponding to a conjugation capacity of 855 micrograms DDA/h/g fresh weight of cells.

Chromatography, Affinity↗
PubMed2001

Purification and characterization of glutathione conjugate reductase: a component of the tetrachlorohydroquinone reductive dehalogenase system from Phanerochaete chrysosporium.

A membrane-bound glutathione S-transferase and a soluble glutathione conjugate reductase constitute the reductive dehalogenase system of P. chrysosporium. This enzyme system reductively removes chlorine substituents from tetrachlorohydroquinone, a metabolite of pentachlorophenol. The membrane-bound glutathione S-transferase converts tetrachlorohydroquinone to S-glutathionyltrichloro-1,4-hydroquinone, which is subsequently reduced to 3,5,6-trichlorohydroquinone by the soluble glutathione conjugate reductase (GCR). This GCR can accept glutathione, dithiothreitol, cysteine, or beta-mercaptoethanol as cosubstrates. GCR was purified to apparent homogeneity by ion-exchange and covalent chromatography. The enzyme exhibits optimum activity at pH 6.0 and 55 degrees C and appears to be a homodimer with a M(r) of approximately 60 kDa. Activity increases as the number of chlorine substituents on the hydroquinone ring is increased. GCR has an apparent K(m) of approximately 33 microM and an apparent k(cat) of approximately 3.43 s(-1) for 2-S-glutathionyl-3,5,6-trichloro-1,4-hydroquinone. Inhibitors of GCR include Cd(2+), Fe(2+), Mn(2+), iodoacetic acid, and p-chloromercuribenzoic acid, suggesting the presence of a catalytic cysteine thiol(s) at the active site. When glutathione is used as a cosubstrate, reduction of S-glutathionyltrichloro-1,4-hydroquinone is accompanied by the production of trichlorohydroquinone and oxidized glutathione in a 1:1 ratio. A mechanism for this novel enzyme is proposed.

Glutathione↗
PubMed1996

Inhibition of progesterone receptor activity in yeast by synthetic chemicals.

Numerous synthetic chemicals have estrogenic activity by interacting with the estrogen receptor. In this report, we test the hypothesis that some estrogenic chemicals may also modulate the human progesterone receptor (hPR) signaling pathway. This was evaluated by examining synthetic chemicals for their ability to modulate the activity of hPR expressed in yeast. The transcriptional activity of hPR was not increased in the presence of several synthetic chemicals. However, the estrogenic chemicals p-nonylphenol and 4-tert-octyphenol, and pentachlorophenol, effectively inhibited the activity of the hPR in yeast. Competition binding studies indicated these chemicals effectively competed with radiolabeled R5020, a synthetic progestin, for binding to the hPR in yeast. These results indicate that some synthetic chemicals directly inhibit the activity of hPR in yeast. The observations that some estrogenic chemicals can also inhibit hPR activity suggest a potential mechanism for the reported potent estrogenic activities of these chemicals.

Binding, Competitive↗
PubMed1997

In vitro selection of DNA to chloroaromatics using magnetic microbead-based affinity separation and fluorescence detection.

In vitro selection (SELEX) of DNA ligands to the chloroaromatics, 4-chloroaniline (4-CA), 2,4,6-trichloroaniline (TCA) and pentachlorophenol (PCP), was performed by a novel method utilizing magnetic beads (MBs) having a linker arm for immobilization. Use of MBs was advantageous in obviating elution and precipitation of DNA as conjugated MBs with surface-captured template DNA could be directly added to PCR mixtures. In addition, a simplified PCR scheme requiring only one type of primer and a rapid fluorescence microscopic method for assessing nucleic acid binding after each round of SELEX were demonstrated.

Aniline Compounds↗
PubMed1999

A two-component tetrachlorohydroquinone reductive dehalogenase system from the lignin-degrading basidiomycete Phanerochaete chrysosporium.

Tetrachloro-1,4-hydroquinone (TClHQ) is an intermediate in the degradation of pentachlorophenol by the lignin-degrading basidiomycete Phanerochaete chrysosporium. Two enzymes required for the reductive dehalogenation of TClHQ to trichlorohydroquinone (TrClHQ) were identified in cell-free extracts of P. chrysosporium. In the presence of GSH, a membrane-bound enzyme converted TClHQ to the glutathionyl conjugate of TrClHQ (GS-TrClHQ). This membrane-bound glutathione transferase was specific for GSH as a cosubstrate. In the second step of the reductive dehalogenation reaction, a soluble enzyme fraction converted GS-TrClHQ to TrClHQ in the presence of GSH, cysteine, or dithiothreitol. Thus, this second enzyme appears to be a GS-conjugate reductase. These two enzyme fractions, working in tandem, also reductively dehalogenated TrClHQ and 2,6-dichlorohydroquinone, which are intermediates in the degradation of chlorophenols by this organism.

Cell Fractionation↗
PubMed1999

Characterization of 2,6-dichloro-p-hydroquinone 1,2-dioxygenase (PcpA) of Sphingomonas chlorophenolica ATCC 39723.

Pentachlorophenol (PCP) is a general biocide and a major environmental pollutant. The initial steps of PCP degradation by Sphingomonas chlorophenolica ATCC 39723 have been studied and characterized. Two enzymes are responsible for converting PCP to 2, 6-dichloro-p-hydroquinone (2,6-DiCH) which is a common metabolic intermediate of the biodegradation of polychlorinated phenols. 2, 6-DiCH is degraded by PcpA from strain ATCC 39723, but the reaction end product has been misidentified as 6-chlorohydroxyquinol and has been elusive to detection. We report here the overproduction of PcpA in Escherichia coli and the demonstration of quantitative conversion of 2,6-DiCH to 2-chloromaleylacetate with the coconsumption of one equivalent O(2) and release of one equivalent Cl(-) by purified PcpA. On the basis of the reaction stoichiometry, the enzyme is proposed to be 2,6-DiCH 1,2-dioxygenase.

Bacterial Proteins↗
PubMed1993

Comparison of bacterial toxicity tests based on growth, dehydrogenase activity, and esterase activity of Pseudomonas fluorescens.

Bacterial test systems that are used to assess the environmental risk of chemicals show considerable differences in sensitivity to toxic chemicals. This variation may be caused by differences in sensitivity between species and test parameters of the test systems. In this study, the differences in sensitivity of three test parameters, growth, esterase activity, and dehydrogenase activity, using Pseudomonas fluorescens as the test organism, were studied. The effect of eight substances was tested: pentachlorophenol, 2,4-dichlorophenol, aniline, trichloroethylene, nonylphenolethoxylate, tetrapropylene benzene sulphonate, copper, and nickel. None of the three test parameters was the most sensitive to all substances, although dehydrogenase activity showed a high sensitivity in most cases. The observed differences in sensitivity among the three test parameters were of the same order of magnitude as those previously observed for different strains of bacteria. It was concluded that the choice of test parameter is just as important as the choice of test species to the sensitivity of a test system. The differences in sensitivity between test parameters and between species may account for a great deal of the observed variation between test results obtained with different methods.

Bacteriological Techniques↗
PubMed1994

Ecotoxicological studies with the freshwater rotifer Brachionus calyciflorus. IV. Rotifer behavior as a sensitive and rapid sublethal test criterion.

The swimming behavior of the freshwater rotifer Brachionus calyciflorus exposed to copper (Cu), pentachlorophenol (PCP), 3,4-dichloroaniline (DCA), and lindane, for periods ranging from 5 min to 5 hr, was examined. A swimming behavior test is described which is based on the rotifers' movement rates as they swim over a grid. For all four toxicants a clear dose-response was observed, with the swimming activity decreasing with increasing toxicant concentrations. For Cu the EC50's, the concentration that reduced the swimming activity to 50% of that of the control value, sharply decreased from 0.22 mg/liter after an exposure of 5 min to 0.068, 0.038, and 0.014 mg/liter after exposures of 30, 60, and 300 min, respectively. PCP affected the rotifers' swimming behavior more gradually, with EC50's decreasing from 7.0 mg/liter after an exposure of 5 min to 5.9, 5.4, and 1.5 mg/liter after 30, 60, and 300 min, respectively. A similar pattern was found for DCA with EC50's ranging from 193 to 45.5 mg/liter for the 5-min and 3-hr exposures, respectively. Exposed to lindane however, B. calyciflorus swimming activity exhibited a different response, and the EC50's gradually increased from 13.7 mg/liter after an exposure of 5 min to significantly higher values of 16.4 and 18.5 mg/liter after periods of 1 and 5 hr, respectively. The results of the swimming activity assays were compared to those of acute and chronic toxicity tests performed with the same test species. The potential use and relevance of this behavioral test criterion were evaluated and discussed.

Aniline Compounds↗
PubMed1998

A new low-cost microbiotest with the Protozoan spirostomum teres: culture conditions and assessment of sensitivity of the ciliate to 14 pure chemicals.

This paper defines the culture conditions of the ciliate Spirostomum teres and assesses its sensitivity to some xenobiotics for the development of a new low-cost microbiotest. The model was selected for its ubiquitous distribution, large size for a unicellular species, easy culture in holoxenic medium, moderate generation time, and high sensitivity to pure toxicants. The influence of different culture waters, inocula of ciliates, food, temperature, light, and darkness on the growth of the ciliate population was tested. The shortest generation time (average 39 h) was obtained for cultures incubated at 25 degreesC in the dark with an inoculum of 4 ciliates per ml in 25 ml of Volvic mineral water containing 8 boiled wheat grains, when preincubated without ciliates for the previous week. Under these conditions, it was possible to obtain about 3000 ciliates/ml 3 weeks later. Acute toxicity tests (24-h LC50) were carried out for CuSO4, HgCl2, CdCl2, K2Cr2O7, ZnSO4, Pb(NO3)2, thiram, carbaryl, lindane, parathion, parathion methyl, paraoxon, 2, 4,6-trichlorophenol, and sodium pentachlorophenolate (Na-PCP). Very high sensitivity of the model to Hg2+, Cu2+, Cd2+, thiram, and Na-PCP was established. Comparison of its sensitivity with that of Microtox (current results), Daphnia Magna, Tetrahymena pyriformis, Colpidium campylum, and murine fibroblasts (data from literature) confirms the high sensitivity of the model, especially to heavy metals. Easy-to-perform, cost-effective, and sensitive bioassays using S. teres are suitable for risk assessment and early detection of toxicity in fresh water.

Animals↗
PubMed1999

Effects of organic pollutants on soil microbial activity: the influence of sorption, solubility, and speciation.

The Fe(III) reduction test was used to measure the toxicity of 12 organic chemicals [dichlorophenoxyacetic acid (2,4-D), trichlorophenoxyacetic acid (2,4,5-T), atrazine, picloram, 4-chlorobenzeneamine, pentachlorophenol (PCP), hexachlorobenzene (HCB), 1,1-bis-4-chlorophenyl-2,2,2-trichloroethane (DDT), trichloroethene, benzene, phenol, linear alkylbenzenesulfonate (LAS)]. The different inherent toxicity of the pollutants is strongly modified by interactions with the soils. The total amounts that cause 10, 50, and 90% inhibitions (effective doses, ED10, ED50, ED90) can be statistically related to soil parameters that control the sorption and solubility of the chemicals. Sorption experiments with 2,4-D, 2,4,5-T, PCP, and LAS confirm that the degree of sorption and the concentration in the soil solution are important for potential toxic effects. However, toxic solution concentrations of a chemical (effective concentrations, EC10, EC50, EC90) also vary considerably. For some chemicals the influence of soil pH on their speciation in the soil solution is mainly responsible for this, e.g., the transformation from anionic to nonionic species with decreasing pH. The nonionic species of 2,4-D, 2,4,5-T, and PCP formed under acidic conditions are more toxic than the anionic species. Thus, depending on the chemical parameters of the soils that determine the degree of sorption and the speciation of toxicants in the liquid phase, soils either can "buffer" high loads of toxicants or can be very sensitive toward contamination.

Dose-Response Relationship, Drug↗
PubMed1993

Comparing the results of a Monte Carlo analysis with EPA's reasonable maximum exposed individual (RMEI): a case study of a former wood treatment site.

In the United States, there are about 250 former sites that treated wood with preservatives that are now in need of some degree of remediation. The soil at many of these sites is contaminated with creosote, polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs). This paper compares the results of the current USEPA point estimate (deterministic) approach for predicting the health risks associated with exposure to PCDDs/PCDFs in soil with the results of a probabilistic approach which uses a Monte Carlo analysis. At many of these wood treatment sites the hazard posed by the PAHs, and especially pentachlorophenol, can be much greater than that due to PCDD and PCDFs; however, because at this site the health risk associated with PAHs was deemed negligible by ATSDR, only PCDDs/PCDFs were evaluated. Octachlorodibenzo-p-dioxin (OCDD) and octachlorodibenzofuran (OCDF) congeners were evaluated independently from the other congeners due to their prevalence in the environment and the availability of congener-specific data. The results of the reevaluation of the rodent bioassay data for 2,3,7,8-TCDD were considered in the probability distribution for the cancer potency factor. The authors' analyses indicate that when assessing exposure to soil via inhalation, ingestion, and dermal contact, the current regulatory approach used to estimate the reasonable maximally exposed individual (RMEI) (USEPA, Risk Assessment Guidance for Superfund, Vol. 1, Part A, 1989) can predict risks which are 10- to 100-fold greater than the 95th percentile risk predicted by a Monte Carlo analysis.

Abnormalities, Drug-Induced↗
PubMed1993

The role of oxidative metabolism in hexachlorobenzene-induced porphyria and thyroid hormone homeostasis: a comparison with pentachlorobenzene in a 13-week feeding study.

Hexachlorobenzene (HCB) induces a broad spectrum of effects including disturbances in the heme synthesis (porphyria) and in thyroid hormone homeostasis. For most of its effects, biotransformation of the parent compound seems to be a prerequisite. The present study was designed to assess the relevance of the oxidative metabolites in HCB-induced toxicity, with special attention to the role of the reactive tetrachlorobenzoquinone (TCBQ). To this end, toxicity and biotransformation of HCB were compared with those of pentachlorobenzene (PCB), since this chemical is oxidized to the same products as HCB, i.e., pentachlorophenol (PCP) and TCBQ. Female Wistar rats received diets containing different dose levels of HCB or PCB for 13 weeks, with or without cotreatment with triacetyloleandomycin (TAO), a selective inhibitor of cytochrome P450IIIA1/2. Rats treated with HCB (high dose) had significantly elevated levels of urinary porphyrins from the 4th week on and had a significant hepatic accumulation of porphyrins at the end of the study. Both urinary porphyrin excretion and hepatic porphyrin accumulation were greatly inhibited in rats receiving cotreatment with HCB and TAO. However, the inhibition of HCB-induced porphyria by TAO cannot be explained by a diminished formation of the highly reactive TCBQ, since rats treated with a high dose of PCB, which had a several fold higher urinary excretion of PCP and TCHQ compared to a high dose of HCB, did not develop porphyria. Instead, the present study points to the involvement of a putative reactive intermediate in the primary oxidative step in HCB-induced porphyria, since based on paired observations of individual rats, the degree of porphyria was correlated to a high degree with excretion of PCP, whereas correlation of porphyria with early excretion of TCHQ was much weaker. This finding fits well with the fact that the mechanisms of oxidation of HCB to PCP and PCB to PCP are different. Both HCB and PCB were oxidized to PCP and tetrachlorohydroquinone (TCHQ), the reduced analog of TCBQ. Cytochrome P450IIIA1/2 appears to be involved in the conversion of HCB and PCB, since cotreatment of TAO resulted in a strongly diminished urinary excretion of PCP and TCHQ. Treatment with HCB as well as PCB results in disturbances of retinoid and thyroid hormone homeostasis. These effects, which have also been reported after exposure to polychlorinated biphenyls, originate from interference of hydroxylated metabolites (notably PCP) with the plasma thyroxine transport protein, transthyretine, and since this metabolite is formed from both HCB and PCB, this results in the same toxicity for both compounds.

Animals↗
PubMed1991

Degradation of xenobiotics by white rot fungi.

White rot fungi such as P. chrysosporium degrade the nonrepeating, nonstereoselective, insoluble polymer lignin under conditions of nutrient limitation. The attack on lignin principally involves extracellular peroxidases (ligninases) and hydrogen peroxide. Hydroxyl radicals may also make a significant contribution. The ligninolytic system lends itself to the degradation of xenobiotics, since these often have limited solubility in water and are not readily available in soil to intracellular metabolism. A nonspecific attack should proceed at a rate independent of the target's concentration and the fungal system would be expected to remediate soil contaminated with a mixture of compounds. This contrasts with the need for induction and problems with simultaneous metabolism encountered with bacterial inoculation. The P. chrysosporium system has been found active against such diverse substrates as DDT, lindane, PCBs, TNT and crystal violet, with substantial mineralization in many cases. Some like biphenyl and triphenylmethane dyes are structurally related to lignin substructures while others bear groups such as nitro (TNT) or halogen (PCP) that are absent from the natural polymer. The fate of transformed targets varies: pentachlorophenol is incorporated into soil organic matter as a result of fungal ligninase action, whereas highly lipophilic Aroclor PCBs are converted to water-soluble metabolites. Normally less toxic intermediates are generated: for example, with benzo[a]pyrene, mutagenic arene oxides do not appear in the white rot fungal system. In certain cases, purified ligninases were also active in degrading pollutants such as PCP, benzo[a]pyrene or triphenylmethane dyes. Methods of optimizing ligninase activity in fungal reactors have been described, such as the addition of surfactants and veratryl alcohol to the medium. It remains to be seen how molecular biology can provide further advances in maximizing the bioremediating activity of white rot fungi applied to contaminated soil.

Basidiomycota↗
PubMed1996

Chlorophenols in the terrestrial environment.

Chlorophenols are presently widespread in the environment. Even in the most remote natural environments, the presence of chlorophenols in both aquatic and terrestrial food chains has been recorded. These pervasive compounds have been used for a wide range of domestic, agricultural, and industrial purposes for more than 50 years. In addition to industrial production and usage, chlorophenols are produced from naturally occurring phenols as a result of chlorine bleaching of wood pulp in the paper industry and through the chlorination of domestic water supplies and swimming pools. It must be emphasized that chlorophenols, although a local problem in some areas, generally cannot be considered a major environmental problem today because their use is prohibited or restricted in many countries. Future reduction in the use of the herbicidal phenoxy acids will further minimize their levels in the terrestrial environment. Because of the long persistence and high toxicity of pentachlorophenol in particular, however, it is important that the discharge of chlorophenols to the terrestrial environment by way of sewage sludge or pulp mill effluents be maintained at their current levels or even reduced to lower levels.

Animals↗
PubMed1984

Land disposal and spill site environments.

Land is a receptor of many chemicals through both intentional and unintentional depositions. Mitigation methods for control of the chemicals resulting from unintentional depositions such as unsuccessful landfills, spills, and leaks include excavation and disposal, entombment in place, and in some situations, in situ biodegradation. If genetically engineered bacteria could expand the number of situations where in situ degradation is applicable, then more economically efficient control methods resulting in the destruction of chemicals would be available. This paper outlines the various processes affecting the fate of organic chemicals in the soil environment, summarizes the environmental conditions encountered by organisms, and reviews two case histories of biodegradation of chemicals within the soil environment. Environmental conditions encountered by organisms are distinctly different in the two major soil zones: the unsaturated zone and the saturated zone. Chemicals may be present within the soil environment including the vapor phase, the adsorbed phase, and the soluble phase. These differences affect the fates of each chemical and result in greatly different rates of biodegradation of chemicals by naturally occurring microorganisms. Case histories discussed are that of a spray irrigation field treating wastewater from a creosote wood treating process, and that of an in situ biodegradation program for clean up of surface soils contaminated with pentachlorophenol. Recommendations for bacterial characteristics that could be engineered to greatly expand the applicability of in situ biodegradation are made.

Biodegradation, Environmental↗
PubMedDate not supplied

Degradation of polychlorinated phenols by Streptomyces rochei 303.

The strain Streptomyces rochei 303 (VKM Ac-1284D) is capable of utilizing 2-chloro-, 2,4-, 2,6-dichloro- and 2,4,6-trichlorophenols as the sole source of carbon. Its resting cells completely dechlorinated and degraded 2-, 3-chloro-; 2,4-, 2,6-, 2,3-, 2,5-, 3,4-, 3,5-dichloro-; 2,4-, 2,6-dibromo-; 2,4,6-, 2,4,5-, 2,3,4-, 2,3,5-, 2,3,6-trichlorophenols; 2,3,5,6-tetrachloro- and pentachlorophenol. During chlorophenol degradation, a stoichiometric amount of chloride ions was released and chlorohydroquinols were formed as intermediates. In cell-free extracts of S. rochei, the activity of hydroxyquinol 1,2-dioxygenase was found. The enzyme was induced with chlorophenols. Of all so far described strains degrading polychlorophenols, S. rochei 303 utilized a wider range of chlorinated phenols as the sole sourse of carbon and energy.

Biodegradation, Environmental↗