The survival of the pentachlorophenol-degrading Rhodococcus chlorophenolicus PCP-1 and Flavobacterium sp. in natural soil (original) (raw)
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Soil Biology and Biochemistry, 2008
The response of a fresh, agricultural soil when contaminated with pentachlorophenol (PCP) and supplemented with compost (C) or dissolved organic matter (DOM) was studied in the laboratory. The concentration of PCP and the changes in various functionally related properties (i.e. microbial biomass, basal respiration, soil hydrolase and oxidoreductase activity) were measured over 150 d. Variations in the main physical and chemical properties of the soils were also monitored. Two different doses of compost (C1 ¼ 0.27% and C2 ¼ 0.83%, corresponding to 10 and 30 t ha À1 , respectively) or DOM (D1 ¼ 0.07% and D2 ¼ 0.2%) equivalent to the carbon content of the two compost doses C1 and C2 were used and the following five systems were investigated: soil (S), soil-compost (S-C1 and S-C2) and soil-DOM (S-D1 and S-D2). PCP concentrations declined progressively and significantly with time. This effect was most pronounced for the soils amended with the lower compost dose C1 (S-C1) and with the two DOM (S-D1 and S-D2) amounts. Significantly reduced amounts of PCP were extracted after its 500-d residence in the various systems. Higher amounts of the residual PCP were extracted from the humic acids (HA), fulvic acids (FA) and humin-mineral (HU) fractions of the 500 d aged samples than from the same unfractionated samples, indicating that the residual PCP preferentially accumulated in the organic fractions of soil. The soil showed an endogenous microbial activity as indicated by basal respiration, microbial biomass and all the enzymatic activities tested (dehydrogenase, glucosidase, phosphatase, arylsulphatase and urease). Addition of the PCP severely depressed some of the tested biochemical properties suggesting an inhibitory effect on microbial activity. Conversely, higher basal respiration, and similar b-glucosidase and phosphatase activities were measured in comparison with the controls. No significant effects were observed following the addition of two doses of the compost or the DOM. Fungal colonies belonging to the taxonomic group of Ascomycetes and identified as Byssochlamys fulva developed with time in all the PCPcontaminated samples. Growth of B. fulva in vitro in the presence of PCP showed that the isolate was tolerant to 12.5 and 25 mg l À1 PCP and degraded 20% of its initial concentration in 8 d. Overall, the results indicate that many complex processes occurred in the contaminated soil and combinations of these determined the response to PCP contamination. The sorption of PCP to the soil matrix (which increased with time) and its degradation/transformation by indigenous soil microbial activity were likely involved. Both the processes appeared to be favoured by the presence of dissolved organic matter.
Soil Biology and Biochemistry, 1994
Mineralization of pontachlorophenol (PCP) was studied in non-sterile soil using Rhodococcus chforophenolicus strain PCP-I. The effect of the inoculum size, concentration of PCP and soil moisture on mineralization of PCP was investigated in two different types of soil. Non-sterile peaty and sandy soils, containing from 30 to 600 ma af PCP kg-' soil drv wt were inoculated to a density of from 500 to IO* R. chloro&nolicus cells g*" ioil.-_ A mass balance of PC&-carbon and chloride in the inoculated soils was made after exposure for 200 days. The products from PCP-mineralized carbon and released chloride were related to the degraded PCP in ~~iy~ontaminat~ soils. The degree of mineralization of PCP responded positively to an increase in the numbers of R ~h~orop~en#~j~ ceIk. The mineral&zing capacity per &o&ant ceI1 was higher (40 fg PCP day-') in soil with 350 and 600 mg PCP kg-' dry wt than in soit with 3Omg PCP kg-' dry wt (4 fg PCP day-'). T&e min~i~tion was similar in soil with a high content of organic matter (30%) to that in mineral soil (I 7% organic matter). The rate of degradation of PCP by indigenous soil microbes in sand and in peat was equivalent to 0,3 and 1 mg PCP kg-' dry wt month-', respectively. This indicates that unforced bioremediation would require years for completion, even at a Iow concentration of PCP pollution. The results also show that more than lo7 active R. chlorophenolicus cells should be applied g-' soil to ensure effective mineralization of PCP in the soil.
Soil Biology and Biochemistry, 1990
fate of pentachlorophenol (PCP) in three sterile soils inoculated with a white-rot basidiomyccte. Phwwrvrhaw rhr~.~f~.~porittnt. was investigated. Mineralization and volatilization of PCP and its transformation products and residual PCP concentration were measured for 2-months from soil microcosms inoculated with f? chr,wqxwiurn or left non-inoculated. There was a drnmatic dt%rease (ave. dkyrease 98%) in the CXtKlCf&C PCP concentration in inocutted soils compared to that in non-inoculated soils (ave. decrease 43%). In the three inr~ulated soils, the greatest loss of PCP was during the first w&TIC. Initial rates of PCP depletion varibvi by soil. Ditfcrwws among these soils in quantities of soil nutrients available for fungal growth. particularly carbon and nitrogen, may have been indirectly responsible for the differences by influencing the rates of soil colonitation. Pen~~~hl[~ropheno~ mineralized or evolved as volatile products was slight in the three soils. Our results suggest that P. rhrywqoriunt remova PCP pc'r SC* from soils primarily by converting it to non-volatile products. The nature of the products, whether they are extractable or soil-bound. is greatly influcnccd by soil type. 'Ammonium ~CCLIIC melhod (Thomas. 19X2). 'Kjedahi procedure for Total N (Bremmcr and Mulvany. 19X?).
2010
We determined the toxicity of various chlorophenols, especially pentachlorophenol (PCP), on five bacterial strains and studied PCP biodegradation in soils amended with an organomineral complex (OMC) prepared from humic acids (organic part) bound on zeolite (inorganic part). Both components of OMC have excellent sorption properties and are of natural origin and therefore suitable to be used in the environment. Toxicity of chlorophenols depends not only on the number of chlorine atoms but also on their position on aromatic ring, and is thus regiospecific. Biodegradation of PCP was studied in three real completely characterized soil samples, Chernozem, Fluvisol, and Regosol, with and without the addition of OMC. The soils were sterilized and bioaugmented with the bacterial isolate Comamonas testosteroni CCM 7530. The immobilization effect of OMC in relation to PCP depends on the concentration of humic acids (HAs), the PCP concentration, and the content of organic carbon in soil. The microbial activity and the simulated action of acid rains led to the gradual release and biodegradation of the reversibly bound PCP without no initial toxic effect on indigenous or bioaugmented microorganisms. OMC appeared to be a good trap for PCP with potential applications in remediation technology because it reduces the potential toxicity of PCP to microbial community by lowering its bioavailability and thus facilitates its biodegradation.
2000
The fate of pentachlorophenol (PCP) in three sterile soils inoculated with a white-rot basidiomycete, Phanerochaete chrysosporium, was investigated. Mineralization and volatilization of PCP and its transformation products and residual PCP concentration were measured for 2-months from soil microcosms inoculated with P. chrysosporium or left non-inoculated. There was a dramatic decrease (ave. decrease 98%) in the extractable PCP concentration in inoculated soils compared to that in non-inoculated soils (ave. decrease 43%). In the three inoculated sails, the greatest loss of PCP was during the first week. Initial rates of PCP depletion varied by soil. Differences among these soils in quantities of soil nutrients available far fungal growth, particularly carbon and nitrogen, may have been indirectly responsible for the differences by influencing the rates of soil colonization. Pentachlorophenol mineralized or evolved as volatile products was slight in the three soils. Our results suggest that P. chrysosporium removes PCP per se from soils primarily by converting it to non-volatile products. The nature of the products, whether they are extractable or soil-bound, is greatly influenced by soil type
We evaluated the use of straw compost and remediated soil as inocula for bioremediation of chlorophenolcontaminated soil. The in situ biotransformation of pentachlorophenol (PCP) and mineralization of radiolabeled [U-14 C]PCP by straw compost and remediated soil were studied under field-simulating conditions before and after 3 months of adaptation with PCP in a percolator. After PCP adaptation, the straw compost mineralized up to 56% of the [ 14 C]PCP. No partial dechlorination of PCP was found. The native straw compost did not mineralize PCP, but partial dechlorination of PCP occurred (i) at pH 8 under near-thermophilic conditions (45؇C) and (ii) at pH 7 under aerobic and mesophilic conditions. No biotransformation reactions occurred at room temperature (25؇C) at pH 8. Enrichment in the percolator enhanced the mineralization rate of remediated soil to 56% compared with that of the native remediated soil, which mineralized 24% of [ 14 C]PCP added. Trace amounts of chloroanisoles as the only biotransformation products were detected in PCP-adapted remediated soil. Both inoculants studied here showed effective mineralization of PCP when they were adapted to PCP in the percolator. No harmful side reactions, such as extensive methylation, were observed.
Evaluation of natural and enhanced PCP biodegradation at a former pesticide manufacturing plant
Water Research, 2004
Pentachlorophenol (PCP) has been used in the past as a pesticide, herbicide, antifungal agent, bactericide, and wood preservative. Thus, PCP is among the most ubiquitous chlorinated compounds found in groundwater contamination. A former pesticide manufacturing plant located in southern Taiwan has been identified as a PCP spill site. In this study, groundwater samples collected from the PCP site were analyzed to assess the occurrence of natural PCP biodegradation. Microcosm experiments were conducted to (1) evaluate the feasibility of biodegrading PCP by indigenous microbial consortia under aerobic and cometabolic conditions, and (2) determine the potential of enhancing PCP biodegradation using cane molasses and biological sludge cake as the substitute primary substrates under cometabolic conditions. The inocula used in this microcosm study were aquifer sediments collected from the PCP site and activated sludges collected from the municipal and industrial wastewater treatment plants. Results from this field investigation indicate that the natural biodegradation of PCP is occurring and causing the decrease in PCP concentration. Microcosm results show that the indigenous microorganisms can biodegrade PCP under both aerobic and aerobic cometabolism conditions. A PCP-degrading bacterium was isolated from the collected aquifer sediments and identified as Pseudomonas mendocina NSYSU via some biochemical tests and further conformation of DNA sequencing. In batch cultures, P. mendocina NSYSU used PCP as its sole source of carbon and energy. The isolated bacterium, P. mendocina NSYSU, was capable of completely degrading PCP as indicated by the increase in biomass formation with the decrease in PCP concentrations occurred in the carbon-free medium simultaneously. Results indicate that the in situ or on-site aerobic bioremediation using indigenous microorganisms or inoculated bacteria would be a feasible technology to clean up the studied PCP-contaminated site. Results from this study will be useful in designing a scale-up in situ or on-site PCP bioremediation system (e.g., on-site bioreactor) for field application. r
Pentachlorophenol and crystal violet degradation in water and soils using heme and hydrogen peroxide
Water Research, 1999
ÐAn abiotic method for oxidative PCP degradation in soil under unsaturated conditions and neutral pH was developed. Reagents used were heme (a catalyst) and peroxide (an oxidant). The aqueous phase degradation of crystal violet and PCP, and the mineralization of PCP in soil were determined. Five factors were investigated to assess their impact on PCP degradation in a soil contaminated with wood preserving chemicals. The results showed that heme and peroxide could eciently degrade PCP and crystal violet in a short period of time in either liquid or unsaturated soil systems. In soil, three control runs showed little degradation of PCP, but treatments with heme and peroxide showed a maximum of 13% mineralization of PCP. Heme and peroxide concentration were the two most important factors in improving degradation of PCP in soil.
Microbial Treatment of Soil to Remove Pentachlorophenol
Applied and Environmental Microbiology, 1983
Direct inoculation of bacteria capable of degrading pentachlorophenol (PCP) into PCP-contaminated soil was investigated as a prophylactic measure to reduce the hazards of runoffs when spills occur or when wooden poles freshly treated with PCP-containing preservatives are located near streams and lakes. In laboratory tests at 30°C, the direct addition of 10 6 PCP-utilizing Arthrobacter cells per g of dry soil reduced the half-life of the pesticide from 2 weeks to <1 day. Soil inoculation also was shown to be an effective way to increase the PCP disappearance rate in a test conducted in an outdoor shed.