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PubMed2005

Gene expression and microscopic analysis of Arabidopsis exposed to chloroacetanilide herbicides and explosive compounds. A phytoremediation approach.

Understanding the function of detoxifying enzymes in plants toward xenobiotics is of major importance for phytoremediation applications. In this work, Arabidopsis (Arabidopsis thaliana; ecotype Columbia) seedlings were exposed to 0.6 mm acetochlor (AOC), 2 mm metolachlor (MOC), 0.6 mm 2,4,6-trinitrotoluene (TNT), and 0.3 mm hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). In vivo glutathione (GSH) conjugation reactions of AOC, MOC, RDX, and TNT were studied in root cells using a multiphoton microscope. In situ labeling with monochlorobimane, used as a competitive compound for conjugation reactions with GSH, confirmed that AOC and MOC are conjugated in Arabidopsis cells. Reverse transcription-PCR established the expression profile of glutathione S-transferases (GSTs) and nitroreductases enzymes. Genes selected for this study were AtGSTF2, AtGSTU1, AtGSTU24, and two isoforms of 12-oxophytodienoate reductase (OPR1 and OPR2). The five transcripts tested were induced by all treatments, but RDX resulted in low induction. The mRNA level of AtGSTU24 showed substantial increase for all chemicals (23-fold induction for AOC, 18-fold for MOC, 5-fold for RDX, and 40-fold for TNT). It appears that GSTs are also involved in the conjugation reactions with metabolites of TNT, and to a lesser extent with RDX. Results indicate that OPR2 is involved in plant metabolism of TNT (11-fold induction), and in oxidative stress when exposed to AOC (7-fold), MOC (9-fold), and RDX (2-fold). This study comprises gene expression analysis of Arabidopsis exposed to RDX and AOC, which are considered significant environmental contaminants, and demonstrates the importance of microscopy methods for phytoremediation investigations.

Acetamides↗

PubMed2005

Effect of urea on degradation of terbuthylazine in soil.

Pesticide and nitrate contamination of soil and groundwater from agriculture is an environmental and public health concern worldwide. The herbicide terbuthylazine (CBET) has replaced atrazine in Italy and in many other countries because the use of the latter has been banned because of its adverse environmental impacts. Unlike atrazine, knowledge about the fate of CBET in soil is still not extensive, especially regarding its transformation products, but recent monitoring data show its occurrence and that of its main metabolite, desethyl-terbuthylazine (CBAT), in groundwater above the limit of 0.1 microg/L established by European Union Directive and Italian legislation. The objective of this work was to investigate if the presence of the fertilizer urea affects CBET degradation in the soil. Laboratory CBET degradation experiments in the presence/absence of urea were performed with microbiologically active soil and sterilized soil. Terbuthylazine degradation rates under the different experimental conditions were assessed, and the formation, degradation, and transformation of the metabolite CBAT were also studied. Terbuthylazine degradation was affected by the presence of urea, in terms both of a higher disappearance time of 50% of the initial concentration and of a lower amount of CBAT formed. These findings have practical implications for the real-life assessment of the environmental fate of triazine herbicides in agricultural areas since these herbicides are frequently applied to soils receiving ureic fertilizers.

Bacteria↗

PubMed2003

Remediation of Hanford's N-reactor liquid waste disposal sites.

Hanford's N-Reactor operated from 1963 to 1987 generating approximately 9 x 10(7) m3 of radioactive and hazardous liquid effluent as a result of reactor operations. Two liquid waste disposal sites, essentially large trenches designed to filter contaminants from the water as it percolates through the soil column, were established to dispose of the effluent. The discharges to the sites included cooling water from the reactor primary, spent fuel storage, and periphery systems, along with miscellaneous drainage from reactor support facilities. Today, both sites are classified as Treatment Storage and Disposal Facilities under the Resource Conservation and Recovery Act of 1976, which makes them priority sites for remediation. The two sites cover approximately 4,100 m2 and 9,300 m2, respectively. Remediation of the sites requires removing a combined total of approximately 2.6 x 10(8) kg of contaminated soil and debris. Principal radionuclides contained in the soil/debris are 60Co, 137Cs, 239Pu, and 90Sr. Remediation of these waste sites requires demolishing concrete structures and excavating, hauling, and disposing of contaminated soils in work areas containing high levels of contamination and whole body dose rates in excess of 1 mSv h-1. The work presents unique radiological control challenges, such as minimizing external dose to workers in a constantly changing outdoor work environment, maintaining contamination control during removal of a water distribution trough filled with highly contaminated sludge, and minimizing outdoor airborne contamination during size reduction of highly contaminated pipelines. Through innovative approaches to dose reduction and contamination control, Hanford's Environmental Restoration Contractor has met the challenge, completing the first phase on schedule and with a total project exposure below the goal of 0.1 person-Sv.

Biodegradation, Environmental↗

PubMed1983

Poly(DL-lactide-co-glycolide)/norethisterone microcapsules: an injectable biodegradable contraceptive.

Microcapsules made from a biocompatible, biodegradable polymeric excipient, poly(DL-lactide-co-glycolide) (DL-PLGA) that contained 22 weight percent (wt %) norethisterone (NET), were prepared by a solvent-evaporation microencapsulation process. The effects of changing both the lactide-to-glycolide ratio of the DL-PLGA and the size of the microcapsules on the rate of NET release and the rate of excipient biodegradation were determined in vivo. NET release rates were determined in baboons after injecting the microcapsule formulations intramuscularly. Serum samples obtained at various times following treatment were analyzed for NET, progesterone, and estrogen by radioimmunoassay (RIA). Biodegradation kinetics were determined by injecting NET microcapsules made from radiolabeled DL-PLGA intramuscularly into the hind legs of rats. Residual radioactivity at the injection site was determined at various times after treatment by combustion analysis of the muscle tissue. Changing the ratio of the comonomers to include more glycolide (DL-lactide:glycolide-96:4, 92:8, 87:13, 74:26) increased the rate of NET release and accelerated the biodegradation of the copolymer excipient. Decreasing the size of the microcapsules increased the rate of NET release. On the basis of these studies a NET microcapsule formulation has been identified for clinical testing which releases NET for 3 months and biodegrades completely within 6 months.

Animals↗

PubMed1997

Optimization of environmental factors for the biological treatment of trinitrotoluene-contaminated soil.

In earlier studies (Boopathy et al. 1994a, 1994b), soil bacteria present in a TNT-contaminated site removed 2,4,6-trinitrotoluene (TNT). In this study the optimum conditions for the most efficient removal of TNT is discussed. The results suggest that the soil bacterial consortium has an optimal pH range of 6-7. Maximum growth was observed at pH 7. However, the TNT removal rate was higher at pH 6. Studies of the effects of temperature showed that the bacterial consortium had maximum metabolic activity at 20 to 22 degrees C (ambient temperature). At a higher temperature (37 degrees C) the TNT removal rate dropped significantly. The consortium could not use TNT as a nitrogen source but required the addition of ammonium. Optimal growth occurred with 0.25 g/L of ammonium chloride. Growing cells removed TNT significantly faster rates than resting cells or cell-free extract. The operation of soil slurry reactors with the optimal conditions suggested that TNT can be removed effectively from the contaminated sites. These environmental conditions established as optimal can be used to improve the efficiency of large-scale soil slurry reactors for the treatment of soil contaminated with TNT.

Biodegradation, Environmental↗

PubMed2005

Natural attenuation and enhanced bioremediation of organic contaminants in groundwater.

An area of intense scientific and practical interest is the biogeochemical and microbial processes determining the success of natural attenuation, biostimulation and/or bioaugmentation treatments for organic contaminants in groundwater. Recent studies in this area have focused on the reductive dechlorination of chlorinated solvents, the degradation of the fuel additive methyl tert-butyl ether, and the removal of long-term hydrocarbon contamination. These studies have been facilitated by the use of stable isotope analysis to demonstrate in situ bioremediation and push-pull tests, in which isotopes are injected into aquifers and then quickly retrieved and analyzed, to measure in situ activity. Molecular tools such as quantitative PCR, the detection of mRNA expression, and numerous DNA fingerprinting methods have also proved valuable, being employed to identify and sometimes quantify environmentally important organisms or changes in communities. Methods to track bacteria and tools to characterize bacterial attachment properties have also offered insight into bacterial transport in situ.

Bacteria↗

PubMed2005

Bioremediation of chromium contaminated soil: optimization of operating parameters under laboratory conditions.

Bacterial strains were isolated and enriched from the contaminated site of Tamil Nadu Chromates and Chemicals Limited (TCCL) premises, Ranipet, Tamil Nadu, India. The strain which was isolated from the highly contaminated location had shown high Cr(VI) reduction potential. Cr(VI) reduction was evaluated both in aerobic and anaerobic conditions. Though the aerobic system performed better than the anaerobic one, further study were carried out in the anaerobic condition due to its economic viability. At higher initial concentration, Cr(VI) reduction was not complete even after 108 h, however, specific Cr(VI) reduction, unit weight of Cr reduced/unit weight of biomass was greater at higher concentration. It was found that a bacterial concentration of 15+/-1.0 mg/g of soil (wet weight) 50 mg of molasses/g of soil as carbon source were required for the maximum Cr(VI) reduction. The bioreactor operated at these conditions could reduce entire Cr(VI) (5.6 mg Cr(VI)/g of soil) in 20 days. The Cr(III) thus formed was found to be strongly attached to the soil matrix and the mobility of Cr(III) was negligible as evident from the low concentration of Cr(III) in the leachate. This study showed that bioremediation is a viable, environmental friendly technology for cleaning-up the chromium contaminated site at TCCL, Ranipet, Tamil Nadu, India, and optimal operating conditions under laboratory conditions were evaluated.

Bacteria, Aerobic↗

PubMedDate not supplied

Cell surface display of organophosphorus hydrolase in Pseudomonas putida using an ice-nucleation protein anchor.

A surface anchor system derived from the ice-nucleation protein (INP) from Pseudomonas syringe was used to localize organophosphorus hydrolase (OPH) onto the surface of Pseudomonas putida KT2440. Cells harboring the shuttle vector pPNCO33 coding for the INP-OPH fusion were capable of targeting OPH onto the cell surface as demonstrated by whole cell ELISA. The whole cell activity of P. putida KT2440 was shown to be 10 times higher than those of previous efforts expressing the same fusion protein in Escherichia coli. The capability of expressing enzymes on the surface of a robust and environmentally benign P. putida KT2440 should open up new avenues for a wide range of applications such as in situ bioremediation.

Aryldialkylphosphatase↗

PubMed2001

Widespread potential for microbial MTBE degradation in surface-water sediments.

Microorganisms indigenous to stream and lake bed sediments, collected from 11 sites throughout the United States, demonstrated significant mineralization of the fuel oxygenate, methyl-tert-butyl ether (MTBE). Mineralization of [U-14C]MTBE to 14CO2 ranged from 15 to 66% over 50 days and did not differ significantly between sediments collected from MTBE contaminated sites and from sites with no history of MTBE exposure. This result suggests that even the microbial communities indigenous to newly contaminated surface water systems will exhibit some innate ability to attenuate MTBE under aerobic conditions. The magnitude of MTBE mineralization was related to the sediment grain size distribution. A pronounced, inverse correlation (p < 0.001; r2 = 0.73) was observed between the final recovery of 14CO2 and the percentage content of silt and clay sized grains (grain diameter < 0.125 mm). The results of this study indicate that the microorganisms that inhabit the bed sediments of streams and lakes can degrade MTBE efficiently and that this capability is widespread in the environment. Thus aerobic bed sediment microbial processes may provide a significant environmental sink for MTBE in surface water systems throughout the United States and may contribute to the reported transience of MTBE in some surface waters.

Biodegradation, Environmental↗

PubMed2006

Application of multimedia models for screening assessment of long-range transport potential and overall persistence.

We propose a multimedia model-based methodology to evaluate whether a chemical substance qualifies as POP-like based on overall persistence (Pov) and potential for long-range transport (LRTP). It relies upon screening chemicals against the Pov and LRTP characteristics of selected reference chemicals with well-established environmental fates. Results indicate that chemicals of high and low concern in terms of persistence and long-range transport can be consistently identified by eight contemporary multimedia models using the proposed methodology. Model results for three hypothetical chemicals illustrate that the model-based classification of chemicals according to Pov and LRTP is not always consistent with the single-media half-life approach proposed by the UNEP Stockholm Convention and thatthe models provide additional insight into the likely long-term hazards associated with chemicals in the environment. We suggest this model-based classification method be adopted as a complement to screening against defined half-life criteria at the initial stages of tiered assessments designed to identify POP-like chemicals and to prioritize further environmental fate studies for new and existing chemicals.

Air Movements↗

PubMed2003

A landfarming application technique used as environmental remediation for coal oil pollution.

Since the massive exploitation of the Val d'Agri (Basilicata-Italy) oilfield has started, a lot of environmental pollution accidents have occurred in the same region. This research takes as starting point the heavy accident occurred in the year 2000, when 15,150 kg of coal oil were spilt all over the Agri river bed and the surrounding fields. In that particular case, the environmental reclamation was achieved by the removal of the polluted soil and its dump-storage. This research work suggests an environmental restoration which is an alternative solution to what has been practiced before, and it is achieved by the so called bioremediation methods, particularly the "landfarming on site" technique.

Biodegradation, Environmental↗

PubMed1996

Environmental estrogenic effects of alkylphenol ethoxylates.

Alkylphenol ethoxylates (APEs) and related compounds recently have been reported to be estrogenic because it has been demonstrated in laboratory studies that they mimic the effects of estradiol both in vitro and in vivo. Chemicals referred to as "environmental estrogens" are suspected of causing health effects in both humans and wildlife through disruption of the endocrine system. In this review, the occurrence, environmental fate, and biological effects of APEs are presented. To provide understanding of the potential for endocrine disruption due to environmental estrogens, the physiology of estrogens in mammals and fish is also reviewed. The estrogenic potency of other environmental estrogens is compared to the potency of APE degradation products. The reproductive effects of estrogenic compounds are considered when evaluating the potential health effects of APEs. Given the reported environmental concentrations and bioconcentration factors of APE products, the potential for these compounds to produce estrogenic effects in the environment appears low. Although questions concerning the physiological effects of APEs and other environmental estrogens remain unanswered, there are indications that research is in progress that will lead to better understanding of the risks to humans and wildlife.

Animals↗

PubMed2005

Heavy metal uptake, translocation, and bioaccumulation studies of Triticum aestivum cultivated in contaminated dredged materials.

Phytoremediation is a technology that uses vegetation to remediate contaminants from water, soil, and sediments. Unlike traditional remediation techniques such as soil washing or vitrification, phytoremediation offers a technology that is solar-driven, aesthetically pleasing, and cost effective. Recent studies indicate that winter wheat (Triticum aestivum L.) is a potential accumulator for heavy metals such as lead (Pb) and cadmium (Cd) in hydroponic systems. Based on these findings, a laboratory study was conducted with the primary objective of determining the phytoaccumulation capability of this plant species for heavy metals from contaminated dredged materials (DMs) originating from two confined disposal facilities (CDF). The United States Army Corps of Engineers (USACE) manages several hundred million cubic meters of DMs each year, and 5 to 10 % of these DMs require special handling because they are contaminated with hazardous substances that can move from the substrates into food webs causing unacceptable risk outside CDFs. Phytoremediation may offer an alternative to decrease this risk. Chemical analyses by USACE personnel identified 17 metals in various DMs, but in this present study, only zinc (Zn) and Cd were investigated. Pre-germinated seeds of the test plants were planted under laboratory conditions in pots containing the various DMs and reference soil. Four weeks after planting, plants were harvested and separated into roots and shoots for biomass production and tissue metal concentrations analyses. Results showed that T. aestivum plants have the capacity to tolerate and grow in multiple-metal contaminated DMs with the potential of accumulating various amounts of Zn and Cd. Root and shoot biomass of T. aestivum were not significantly affected by the DMs on which the plants were grown suggesting that this plant species can grow just as well on DMs contaminated by various metals as in the reference soil. No significant differences in the Zn tissue concentrations were observed, differences in Cd tissue concentrations were noted. A maximum concentration of 26 mg Cd kg(-1) DW was detected in T. aestivum shoots. Although Cd tissue concentrations of T. aestivum plants in this study were below the Cd plant hyperaccumulation criterion of >100 mg kg(-1) Cd found in other studies, this plant species however may still have beneficial uses for phytoremediation studies. T. aestivum plants may serve as an indicator plant for environmental assessment and management, in which the concentration of heavy metals (e.g. Cd) mirrors the concentration in the substrate without dying due to phytotoxicity at low metal concentrations.

Arsenic↗

PubMed1998

Degradation of morpholine by an environmental Mycobacterium strain involves a cytochrome P-450.

A Mycobacterium strain (RP1) was isolated from a contaminated activated sludge collected in a wastewater treatment unit of a chemical plant. It was capable of utilizing morpholine and other heterocyclic compounds, such as pyrrolidine and piperidine, as the sole source of carbon, nitrogen, and energy. The use of in situ 1H nuclear magnetic resonance (1H NMR) spectroscopy allowed the determination of two intermediates in the biodegradative pathway, 2-(2-aminoethoxy)acetate and glycolate. The inhibitory effects of metyrapone on the degradative abilities of strain RP1 indicated the involvement of a cytochrome P-450 in the biodegradation of morpholine. This observation was confirmed by spectrophotometric analysis and 1H NMR. Reduced cell extracts from morpholine-grown cultures, but not succinate-grown cultures, gave rise to a carbon monoxide difference spectrum with a peak near 450 nm, which indicated the presence of a soluble cytochrome P-450. 1H NMR allowed the direct analysis of the incubation medium containing metyrapone, a specific inhibitor of cytochrome P-450. The inhibition of morpholine degradation was dependent on the morpholine/metyrapone ratio. The heme-containing monooxygenase was also detected in pyrrolidine- and piperidine-grown cultures. The abilities of different compounds to support strain growth or the induction of a soluble cytochrome P-450 were assayed. The results suggest that this enzyme catalyzes the cleavage of the C-N bond of the morpholine ring.

Acetates↗

PubMed2006

Structural characterization of metabolites of the X-ray contrast agent iopromide in activated sludge using ion trap mass spectrometry.

Identification of degradation products of environmental contaminants is a challenging task because not only are they present in very low concentrations but they are also mixed with complex matrixes that interfere with detection. This work illustrates a simple approach using ion trap mass spectrometry combined with H/D-exchange experiments to elucidate the structures of iopromide metabolites formed during biodegradation in activated sludge. Iopromide is an X-ray contrast agent that has been detected frequently in effluents of wastewater treatment plants and in surface waters due to its persistence and high usage. Three metabolites produced by oxidation of the primary alcohols (forming carboxylates) on the side chains of iopromide were identified in a batch reactor with mixed liquor from a conventional activated sludge. Derivatization of the carboxylic acid to form a methyl ester and interpretation of the MS2 data of this derivative aided in the confirmation of the identities of these metabolites. Furthermore, one metabolite formed by dehydroxylation at the two side chains was identified in a batch reactor with mixed liquor from a nitrifying activated sludge. The MS2 fragmentation pattern of iopromide and its metabolites revealed that the iodinated ring remains intact and that minor transformations in the structure occur during biodegradation of iopromide in biological wastewater treatment plants.

Alcohols↗

PubMed2026

In silico analysis of metal resistance genes in Pseudomonas extremaustralis 2E-UNGS: Genomic insights and safety assessment for wastewater biotreatment.

Pseudomonas extremaustralis 2E-UNGS is a non-pathogenic strain isolated from the polluted Reconquista River basin (Buenos Aires Metropolitan Area, Argentina), with a 20-year history of study focused on its survival strategies that have enabled its application in various processes such as waste biotreatment and biosensing. Regarding bacterial-metal interactions, P. extremaustralis 2E-UNGS is capable of biosorbing Cd(II), Zn(II), and Cu(II), and biotransforming Cr(VI) to Cr(III), facilitating both the removal of these metals from aqueous systems and their use in biosensor development. The complete circular chromosome (6,372,594 bp) has been annotated in the NCBI GenBank under accession number NZ_CP091043.1. The aim of this work was to perform an in-depth exploration of the P. extremaustralis 2E-UNGS genome to support the optimization of sustainable bioprocesses within the One Health framework. To this end, the integration of experimental evidence with a detailed in silico analysis of key genes involved in metal-microorganism interactions, antibiotic resistance, and their interconnections provides valuable insights for the optimization of future biotechnological applications. Considering its antibiotic resistance profile, together with the activation of efflux pumps induced by metal stimuli-particularly observed under Zn(II) exposure-P. extremaustralis 2E-UNGS can be regarded as suitable for the design of confined bioreactor processes, minimizing the risk of potential accidental environmental releases. Therefore, modulation of gene expression emerges as a promising approach to enhance the efficiency of metal-loaded wastewater biotreatments.

Pseudomonas↗

PubMed2005

[Effects of plants on nitrogen/phosphorus removal in subsurface constructed wetlands].

Effects of plants on nitrogen/phosphorus removal was studied in pilot-scale in subsurface constructed wetland, the main contents included nutrient uptake, effects of harvesting and roots on hydraulic condition. The result show that the amounts of nitrogen and phosphorous removed by plant harvesting is about 5% of the total removed nutrients in SFS wetlands. The best harvesting periods is between 9-10 month every year. Plant harvesting may induce fluctuation of outflow; aboveground biomass can stabilize micro-environmental of roots. The roots can also improve hydraulic condition of SFS system, decreasing dead area 5 % - 10 % and extending hydraulic retention time.

Biodegradation, Environmental↗

PubMed2004

Environmental impact of diuron transformation: a review.

Diuron is a biologically active pollutant present in soil, water and sediments. A synthesis of literature data on its physicochemical properties, partitioning behaviour, abiotic and biotic transformations, toxicological and ecotoxicological impacts has been here performed. Data have shown that diuron is generally persistent in soil, water and groundwater. It is also slightly toxic to mammals and birds as well as moderately toxic to aquatic invertebrates. However, its principal product of biodegradation, 3,4-dichloroaniline exhibits a higher toxicity and is also persistent in soil, water and groundwater. Thus, diuron indirectly possesses a significant amount of toxicity and could be a potential poisoning pesticide contaminant of groundwater. Unfortunately, groundwater contamination will still persist despite the progressive suppression of diuron (Directive 200/60/CE). Therefore, determining the main factors influencing its degradation and its ecotoxicological effects on the environment and health could provide a basis for further development of bioremediation processes.

Animals↗