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Pentachlorophenol (PCP) is a toxic pollutant. Its biodegradation has been extensively studied in Sphingobium chlorophenolicum ATCC 39723. All enzymes required to convert PCP to a common metabolic intermediate before entering the tricarboxylic acid cycle have been characterized. One of the enzymes is tetrachloro-p-hydroquinone (TeCH) reductive dehalogenase (PcpC), which is a glutathione (GSH) S-transferase (GST). PcpC catalyzes the GSH-dependent conversion of TeCH to trichloro-p-hydroquinone (TriCH) and then to dichloro-p-hydroquinone (DiCH) in the PCP degradation pathway. PcpC is susceptible to oxidative damage, and the damaged PcpC produces glutathionyl (GS) conjugates, GS-TriCH and GS-DiCH, which cannot be further metabolized by PcpC. The fate and effect of GS-hydroquinone conjugates were unknown. A putative GST gene (pcpF) is located next to pcpC on the bacterial chromosome. The pcpF gene was cloned, and the recombinant PcpF was purified. The purified PcpF was able to convert GS-TriCH and GS-DiCH conjugates to TriCH and DiCH, respectively. The GS-hydroquinone lyase reactions catalyzed by PcpF are rather unusual for a GST. The disruption of pcpF in S. chlorophenolicum made the mutant lose the GS-hydroquinone lyase activities in the cell extracts. The mutant became more sensitive to PCP toxicity and had a significantly decreased PCP degradation rate, likely due to the accumulation of the GS-hydroquinone conjugates inside the cell. Thus, PcpF played a maintenance role in PCP degradation and converted the GS-hydroquinone conjugates back to the intermediates of the PCP degradation pathway.

OBJECTIVE: Pentachlorophenol, a fungicide widely used as a wood preservative, was classified in 1999 by the International Agency for Research on Cancer as a possible human carcinogen. We reviewed currently [...]

Pre-treatment of Sphingomonas sp. isolates UG25 and UG30 with pentachlorophenol (PCP) enables the bacteria to degrade higher levels of the pollutant. Pre-treated strains maintained their transmembrane pH gradient and ATP levels in the presence of high levels of PCP, unlike non-treated strains.

Research has been conducted on the tetrachlorohydroquinone dehalogenase. The replacement of chlorine atoms with hydrogen atoms during biodegradation of pentachlorophenol is discussed.

Research has been conducted on the lignin-degrading basidiomycete Phanerochaete chrysosporium. The investigation of the pathway for the pentachlorophenol degradation is presented.

Researchers in Ohio studied means of removing Pentachlorophenol, a wood preservative, from contaminated soil using water, ethanol, and acetone. Figures and tables accompany the article.

Biodegradation of pentachlorophenol (PCP) is discussed as it occurs in a continuous anaerobic reactor with added Desulfitobacterium frappieri PCP-1. The reactor was an upflow sludge bed reactor degrading PCP. To estimate efficiency of augmentation the PCP-1 population in the reactor was enumerated through use of a competitive PCR. Anaerobic degradation of PCP is one process that might benefit from addition of a laboratory strain. The PCP-1 strain seemed to compete well with other microorganisms of the mixed bacterial community.

An alternative approach is described for the measurement of pentachlorophenol (PCP) and its oil solvent in wood samples by supercritical fluid extraction (SFE) and gas chromatography (GC). The determination is achieved over a single chromatographic run using postcolumn flow splitting for simultaneous ECD/FID detection of the SFE extracted species. First, PCP and oil components are quantitatively extracted from a 0.3-g wood sample using 10% MeOH/C[O.sub.2] supercritical fluid at 0.65 g/mL and 120 [degrees] C. An aliquot of the SFE solution is then mixed with 10 mL of a buffered aqueous phase at pH 9.4. After PCP is acetylated by the addition of 500 #L of acetic anhydride, it is followed by its extraction with 2.00 mL of hexane along with oil. Then, 0.5 [[micro]litter] of supernatant organic phase is injected into the GC for a selective and simultaneous determination of the species. The method has a linear response over 3 orders of magnitude for both species with a linear regression correlation coefficient higher than 0.98 (95% confidence limit) and an absolute detection limit of 60 ng of PCP and 80 [[micro]gram] of oil per 0.1-g wood sample. The precision (relative standard deviation) is 4% for PCP and 1% for oil as established for a typical average concentration sample. The accuracy of the SFE GC-ECD/FID combined technique for PCP and oil was assessed by analyzing wood samples collected from newly and in-service PCP/oil-impregnated red pine poles.

Research was conducted to study the disruption of the genomic pcpA gene by gene targeting through the characterization of the mutated gene, homologous recombination, and isolation of pentachlorophenol (PCP) metabolites produced by the mutant strains of Sphingomonas chlorophenolica ATCC 39723 containing the disrupted gene. Cells were washed with sterile deionized water and sterile glycerol. Total genomic DNA was isolated based on the DNAZOL guanidine-detergent lysis method. Moreover, hydroquinone was separated from neutral extracts of cultures incubated with PCP.

The pentachlorophenol (PCP) monooxygenase and tetrachlorohydroquinone (TCHQ) dehydrogenase activities of Sphingomonas chlorophenolica were analyzed to determine the toxic levels of chlorinated hydroquinones in the cytoplasma. The pathway degradation of PCP in Sphingomonas chlorophenolica ATCC 39723 strain involved a monooxygenase and a TCHQ dehydrogenase that catalyzes the conversion of PCP to TCHQ. Furthermore, the toxicity of TCHQ on the cells was concentration-dependent and low levels of the compound did not induces adverse effects in the cells.

Laboratory tests were conducted to determine the effect of soil gas oxygen concentration on the degradation and mineralization of spiked 14C-pentachlorophenol and nonlabeled pentachlorophenol (PCP) present in soil taken from a prepared-bed land treatment unit at the Champion International Superfund Site in Libby, Mont. This soil was contaminated with wood preserving wastes including creosote and PCP. Degradation rates of 14C-PCP and nonlabeled PCP were found to be enhanced under soil gas oxygen concentrations between 2 and 21% in the contaminated soil. Between 48 and 64% of 14C-PCP spiked onto the soil was mineralized after 70 days at soil gas oxygen levels between 2 and 21%. No statistically significant mineralization of PCP was found to occur at 0% oxygen concentrations. Mineralization of 14C-PCP in contaminated soil poisoned with mercuric chloride was determined to be less than 0.2%. Degradation of indigenous nonradiolabeled PCP in the nonpoisoned soil was statistically significantly greater than in poisoned soil. These results indicated that degradation of PCP was biological and would occur under low oxygen concentrations. Soil gas oxygen concentrations necessary for PCP biodegradation (2-5%) could be maintained, for example, using bioventing technology in order to achieve continued treatment of buried lifts of soil while new lifts are added, thus decreasing the total time for soil remediation of the prepared bed.

A competitive magnetic particle-based immunoassay was developed to accurately detect specific pentachlorophenol (PCP) in water and soil. Anti-PCP serum coupled magnetic particles were prepared by glutaraldehyde activation of the magnetic particle solid phase. Experimental results from samples with no pretreatment and from various soil types were compared.

p-Chloranil hydrolyzes at near-neutral to slightly acidic pH to produce trichlorohydroxyquinone and chloranilic acid, two compounds that have known genotoxic effects associated with pentachlorophenol. Electrospray mass spectrometry is used to describe the products of the two-step hydrolysis of chloranil. The kinetics of each step are also described.

The use of potassium polyethylene glycol (KPEG) for the dehalogenation of pentachlorophenol-containing wood preserving waste was investigated. The results showed that KPEG was effective in dehalogenating the pentachlorophenol contained in the waste material. In addition, it was found that dehalogenation using KPEG decreases, but does not completely eliminate, waste genotoxicity during treatment.

A study was conducted on the sorption of pentachlorophenol (PCP) to the surfactant-modified HDTMA-clay and the solubility of PCP as a function of hydrogen-ion concentration (pH) and ionic strength. A model was developed to describe sorption within an experimental pH range of 4-8.5. Results showed that sorption decreases by three times and the solubility rises by three orders of magnitude within the pH range as the dominant aqueous species shifts from the protonated to the deprotonated form.

Pentachlorophenol (PCP) adsorption and mobility in water-saturated soil columns was quantified through kinetic, transport, and equilibrium experiments. Results showed that natural dissolved organic matter (NDOM) does not influence the PCP adsorption rate on soil at a hydrogen-ion concentration (pH) of 5.4 and 6.3 and minimally affects isotherm parameter estimates at pH 5.2, 5.4 and 6.1. It was concluded that NDOM does not induce nor inhibit PCP adsorption and transport in soil columns under conditions found in groundwater-soil systems exposed to nonpoint source contamination.

The adsorption and biodegradation of pentachlorophenol (PCP) by Flavobacterium sp. ATCC 39723 immobilized on polyurethane foam were investigated. The results showed that PCP adsorption followed the Langmuir model, and removal rates were determined primarily by cell growth. Therefore, the addition of cell-utilizable compounds such as glucose and sodium glutamate greatly enhanced biodegradation. Models for both free- and immobilized-cell degradation kinetics were developed.

The feasibility of using hydrogen peroxide as a chemical oxidant for the in situ treatment of soils contaminated with chlorinated hydrocarbons was investigated. Experiments were conducted on sand columns containing pentachlorophenol (PCP) and trichloroethylene (TCE) in the presence and absence of ferrous sulfate. The results showed that hydrogen peroxide decomposed readily by interacting with iron, and both PCP and TCE adsorbed on sand were oxidized effectively.

The chemical reactivities of perchlorodiphenylcarbene (2a) obtained through photolysis and a prepared bis(pentachlorophenyl)diazomethane were examined using both product analysis and flash photolysis techniques. Dimerization was the major reaction found for 2a resulting in the formation of perchlorotetraphenylethylene. Product distribution revealed that although similar dimerization was observed in 2,2',4,4',6,6'-hexachlorodiphenylcarbene, the carbenic centers of 2a are stronger as a result of protection afforded by the four ortho chloro and four meta chloro groups.

The catalytic action of pentacholorophenol (PCP) hydroxylase and its displacement of different substituents in the para position of benzene ring is presented. PCP catalyzes dehalogenation in the degradation of pentachlorophenol and also removes the hydrogen, nitro, amino and cyano group from the para positions of polyhalogenated phenols. Corresponding stoichiometric reactions and equations arising from the study is also presented.

The dechlorination of pentachlorophenol (PCP) in two upflow anaerobic sludge blanket reactors was discussed. One reactor served as control while the other one used glucose as a supplemental carbon source. Results showed 99% of PCP was dehalogenated in the glucose-supplied reactor while only 32-77% was removed from the control reactor. Tests indicated that the glucose-amended reactors performed better because of higher concentration of biomass and the direct effect of glucose on dehalogenation rate. Further analysis also showed that PCP dechlorination involved an initial para cleavage followed by two ortho cleavages.

The mechanism of pentachlorophenol (PCP) hydroxylation by purified PCP hydroxylase from Flavobacterium sp. strain ATCC 39723 was reported. Results from (super 18)O labelling experiments show that the enzyme incorporated (super 18)O from (super 18)O2 but not from H2(super 18)O. PCP is oxidatively converted to tetrachloro-p-hydroquinone by a monooxygenase-type enzyme from Flavobacterium sp. strain ATCC 39723.

The transcriptome response of a common soil bacterium, Pseudomona aeruginosa is examined to the common environmental contaminant pentachlorophenol (PCP). It is observed that the upregulation of the efflux pumps protected the cells from the potentially toxic effects of PCP allowing the physiological whole-cell function to remain constant.

The use of Trametes hirsuta to mineralize pentachlorophenol concentration (PCP) through biorememediation is emphasized. The effect of cyclodextrins on PCP concentration is highlighted.

A pentachlorophenol (PCP)-degrading, methanogenic fixed-film reactor is developed with the use of broken granular sludge from an upflow anaerobic sludge blanket reactor is developed. The result suggests that the presence of PCP-dehalogenating Desulfitobacterium hafniense in the biofilm was crucial for the performance of the reactor.

The solubilization of pentachlorophenol (PCP) by beta-cyclodextrin (beta-CD) is tested along with its three most used derivatives, methyl-beta-cyclodextrin (MCD), hydroxypropyl-beta-cyclodextrin (HPCD) and carboxymethyl-beta-cyclodextrin (CMCD). It was observed that the solubility of beta-CD/PCP complex is lower than that of the beta-CD molecule and depend on the ionic strength of the solution.

Photooxidation of pentachlorophenol (PCP) is reported using a variety of nanosize semiconductor metal oxides and sulfides in both aqueous and polar organic solvents. Photooxidation kinetics of these nanoclusters is compared to widely studied bulk powders such as DegussaP25 TiO2 and CdS.

Strategies to enhance biotransformation of pentachlorophenol (PCP) in a spectrum of wetland soils were investigated under laboratory conditions, which included manipulations of electron acceptors and donors, and PCP concentrations. Maximum transformation rates were found at PCP concentrations [is less than] 10 [micro]M (methanogenic conditions) and [is greater than] 6 [micro]M to [is greater than] 23 [micro]M (aerobic conditions). Differences in PCP toxicity and sorption among soils and treatments were largely governed by the activities of microbial groups. Within this concentration range, transformation was observed in soils under aerobic and methanogenic conditions, but was inhibited under denitrifying and [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]-reducing conditions. Aerobic PCP transformation initially produced small amounts of pentachloroanisole (PCA). However [is greater than] 75% of both chemicals disappeared in 30 d from five soils. Measured soil properties were not significantly correlated to aerobic transformation rates. Under methanogenic conditions, PCP was reductively dechlorinated to yield a mixture of tetra-, tri-, and dichlorophenols in eight soils, with rates strongly correlated to measures of electron donor supply (total C, N, organic C mineralization rates) and microbial biomass. Addition of protein-based electron donors enhanced reductive dechlorination in a soil low in organic matter and microbial biomass. Results demonstrated the widespread occurrence of PCP transforming microorganisms in soils, which may be promoted by manipulating environmental conditions.

Binding of a Fluorescent Ligand to Dimeric Bovine Phenol Sulfotransferase (bSULT1A1) is Biphasic, pH-, and Temperature Dependent. Joe D. Beckmann *, Billie A. Schultz, Meghann K. Devlin, and Rebecca Burkett, [...]

An enzyme that catalyzes an iron-dependent reaction of 2,6-dichlorohydroquinone with O2 is purified from Sphingomonas chlorophenolica strain ATCC 39723, which is capable of complete mineralization of pentachlorophenol. A sequence analysis reveals that the enzyme is an O2-dependent ring cleavage dioxygenase. Moreover, the enzyme is encoded by the pcpA gene and appears to belong to a rare class of extradiol dioxygenases.