SEARCH · PubMed Health

Results for “Biodegradation, Environmental”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 487 records · Page 27Linked to original sources

PubMed2002

Phytomonitoring the unique colonization of oil-contaminated saline environment by Limoniastrum monopetalum (L.) Boiss in Egypt.

A site that covers over 20 acres of coastal saline depression in the western Mediterranean coastal desert of Egypt (El-Hammra station, the main crude oil pipeline terminal in Al-Alamein) is contaminated with crude oil spill as a result of activities from refineries, oilfield blowouts, tanker and pipeline break-ups. This area, prior to contamination, was dominated by different common halophytes. However, Limoniastrum monopetalum is now the only species found growing in the oil-contaminated soil. A specific question addressed in the present study was: what are the biochemical changes occurring in a desert plant growing in oil-contaminated soils? Major metabolites such as proline, betaine, free amino acids, fatty acid esters and mineral elements were studied. The plant samples were collected from the oil-contaminated, as well as noncontaminated, sites. The higher concentration in the selected organic metabolites in the plants growing in the contaminated site compared to those in noncontaminated site may be due to differences in a number of receptors. The sensitivity of such receptors for the environmental signal that cause differences in genetic expression leads to differences in physiological processes. The change in the landscape of the contaminated area and the elimination of the natural vegetation, except L. monopetalum, may explain the competitive balance toward the oil-resistant species.

Amino Acids↗

PubMed2004

Microchip capillary electrophoresis with electrochemical detection of thiol-containing degradation products of V-type nerve agents.

A microchip protocol for the capillary electrophoresis separation and electrochemical detection of thiol-containing degradation products of V-type nerve agents is described. The microchip assay relies on the derivatization reaction of 2-(dimethylamino)ethanethiol (DMAET), 2-(diethylamino)ethanethiol (DEAET), and 2-mercaptoethanol (ME) with o-phthaldialdehyde in the presence of the amino acid valine along with amperometric monitoring of the isoindole derivatives. Both off-chip and on-chip derivatization reactions have led to highly sensitive and rapid detection of the thiol degradation products. Various parameters influencing the derivatization, separation, and detection processes were examined and optimized. These include the amino acid co-reagent, reagent-mixing ratio, reaction time, injection time, separation voltage, and detection potential. The chip microsystem offers a rapid (<4 min) simultaneous detection of micromolar concentrations of DMAET, DEAET, and ME. Linear calibration plots were observed for the V-type nerve agent thiol degradation products, along with good stability and reproducibility (RSD < 8.0%). Detection limits of 5 and 8 microM were obtained for the off-chip reaction of DMAET and DEAET, respectively, following a 2-s injection. The suitability for assays of environmental matrixes was demonstrated for the determination of DMAET and DEAET in untreated tap and river water samples. The favorable analytical performance makes the new microfluidic device attractive for addressing the needs of various security scenarios.

Biodegradation, Environmental↗

PubMed2004

Utilization of enzymes for environmental applications.

Enzymes are powerful tools that help sustain a clean environment in several ways. They are utilized for environmental purposes in a number of industries including agro-food, oil, animal feed, detergent, pulp and paper, textile, leather, petroleum, and specialty chemical and biochemical industry. Enzymes also help to maintain an unpolluted environment through their use in waste management. Recombinant DNA technology, protein engineering, and rational enzyme design are the emerging areas of research pertaining to environmental applications of enzymes. The future will also see the employment of various technologies including gene shuffling, high throughput screening, and nanotechnology. This article presents an overview of the enzymatic applications in pollution control and the promising research avenues in this area.

Biodegradation, Environmental↗

PubMed2004

Enzymatic bioremediation: from enzyme discovery to applications.

1. Enzymatic bioremediation is potentially a rapid method of removing environmental pesticide residues. Applications include the treatment of residues resulting from agricultural production and processing industries, such as the treatment of irrigation waters, surface-contaminated fruit and vegetables and spent dip liquors. 2. A specific application for some organophosphate-degrading enzymes involves detoxification of nerve agent stockpiles. Effective and affordable remediation requires highly specialized enzymes, so protein engineering techniques are being used to improve properties of various source enzymes to enhance catalytic rates, stability and substrate range. 3. Trials with an optimized organophosphate-degrading enzyme have shown the feasibility of such technology in various applications. 4. The enzymes developed for environmental remediation for specific pesticide classes also have applications as antidotes for high-dose pesticide poisonings and as prophylaxis for people at risk of high pesticide doses.

Animals↗

PubMed1995

Mechanisms of degradation by white rot fungi.

White rot fungi use a variety of mechanisms to accomplish the complete degradation of lignin and a wide variety of environmental pollutants. Both oxidative and reductive reactions are required for the metabolism of both lignin and environmental pollutants. The fungi secrete a family of peroxidases to catalyze both direct and indirect oxidation of chemicals. The peroxidases can also catalyze reductions using electron donors to generate reductive radicals. A cell-surface membrane potential can also be used to reduce chemicals such as TNT.

Basidiomycota↗

PubMed1993

Review of leaching characteristics of triazines and their degradation products.

Only few data have been published on the environmental impact of pesticide degradation products on soil and groundwater. It is known that some of the degradation products of triazines, particularly those formed from N-dealkylation reactions, can be phytotoxic and more mobile than their parent compounds. In some cases it has been shown that they are present at even higher concentrations than the latter. Yet, their impact on groundwater quality is unknown since information on both environmental levels and chemiodynamic parameters are generally lacking. The conclusions of this work are that many triazine degradation products may pose a significant hazard to the quality of groundwater and that there is a need to promote and extend the production of experimental data on this topic.

Biodegradation, Environmental↗

PubMed1992

A comparison of test systems for assessing effects of metals on isopod ecological functions.

The effects of metals on the isopod Porcellio scaber and the implication of metal pollution for the functioning of isopods in soil decomposition processes were determined. The experiments were carried out using two test systems, a simple test container without natural substrate and a micro-ecosystem with leaf litter, the latter being more comparable to the field situation. Metals were offered to the isopods by feeding artificially contaminated litter and litter from contaminated field sites. The Cd concentrations in isopods in test containers with ground litter as food were similar to those in isopods in micro-ecosystems with intact leaves as food. Exposure to artificially contaminated litter with Cd alone or litter from contaminated field sites with Cd, Pb, Zn, and Cu resulted in comparable Cd concentrations in the isopods. Growth of the isopods was not affected by Cd or by the combination of Cd, Pb, Zn, and Cu, but differed between the test systems. Fragmentation activity of isopods decreased in litter containing 155 nmol/g Cd and 33500 nmol/g Zn, sampled at a contaminated field site. CO2 production from micro-ecosystems decreased at a concentration of 1010 nmol/g Cd, but NH4 and NO3 concentrations in the litter did not respond to Cd. Isopod growth was better in micro-ecosystems. These systems are therefore recommended for ecotoxicity tests using isopods. After comparison with literature data it was concluded that the bioavailability of Cd in laboratory tests is often higher than the bioavailability in the field at the same total concentrations. This may be due to environmental heterogeneity; this gives animals food choice and is absent in many laboratory test systems. For the quantification of a laboratory-field extrapolation factor for general use, more detailed information is needed than is available now.

Animals↗

PubMed2005

Phenols in anaerobic digestion processes and inhibition of ammonia oxidising bacteria (AOB) in soil.

This study focuses on the presence of phenols in digestate from seven Swedish large-scale anaerobic digestion processes and their impact on the activity of ammonia oxidising bacteria (AOB) in soil. In addition, the importance of feedstock composition and phenol degradation capacity for the occurrence of phenols in the digestate was investigated in the same processes. The results revealed that the content of phenols in the digestate was related to the inhibition of the activity of AOB in soil (EC(50)=26 microg phenols g(-1) d.w. soil). In addition, five pure phenols (phenol, o-, p-, m-cresol and 4-ethylphenol) inhibited the AOB to a similar extent (EC(50)=43-110 microg g(-1) d.w. soil). The phenol content in the digestate was mainly dependent on the composition of the feedstock, but also to some extent by the degradation capacity in the anaerobic digestion process. Swine manure in the feedstock resulted in digestate containing higher amounts of phenols than digestate from reactors with less or no swine manure in the feedstock. The degradation capacity of phenol and p-cresol was studied in diluted small-scale batch cultures and revealed that anaerobic digestion at mesophilic temperatures generally exhibited a higher degradation capacity compared to digestion at thermophilic temperature. Although phenol, p-cresol and 4-ethylphenol were quickly degraded in soil, the phenols added with the digestate constitute an environmental risk according to the guideline values for contaminated soils set by the Swedish Environmental Protection Agency. In conclusion, the management of anaerobic digestion processes is of decisive importance for the production of digestate with low amounts of phenols, and thereby little risks for negative effects of the phenols on the soil ecosystem.

Ammonia↗

PubMed1998

Progress in ultrasonic bioreactors for CELSS applications.

An important issue in Controlled Ecological Life Support Systems (CELSS) is the recycling of inedible crop residues to recover inorganic plant nutrients such as nitrates, phosphates, potassium and other macro- and micro-nutrients. In a closed system in space, such regeneration is vital to the long term viability of plant growth necessary for the food production and waste handling process. Chemical approaches to recycling such as incineration and wet oxidation are not compatible with low energy and environmentally friendly regeneration of such nutrients. Biological regeneration is more acceptable environmentally, but it is a very slow process and does not typically result in complete recovery of inorganic and organic nutrients. A new approach to biological regeneration is described here involving the combined use of special enzymatic catalysts and ultrasonic energy in a bioreactor system. This new system has the potential for rapid, efficient, environmentally friendly and complete conversion of crop wastes to inorganic plant nutrients and food recovery from cellulose materials. A series of experimental tests were carried out with a soybean crop residue meal substrate. Biochemical conversion rates were significantly expedited with the addition of enzymes and further enhanced through ultrasonic stimulation of these enzymes. The difference in conversion rates was particularly increased after the initial period of soluble organics conversion. The remaining cellulose substrate is much more difficult to biodegrade, and the ultrasonically-enhanced reaction was able to demonstrate a much higher rate of substrate conversion.

Biodegradation, Environmental↗

PubMed1989

Hydrocarbon degradation in soils and methods for soil biotreatment.

The cleanup of soils and groundwater contaminated with hydrocarbons is of particular importance in minimizing the environmental impact of petroleum and petroleum products and in preventing contamination of potable water supplies. Consequently, there is a growing industry involved in the treatment of contaminated topsoils, subsoils, and groundwater. The biotreatment methodologies employed for decontamination are designed to enhance in situ degradation by the supply of oxygen, inorganic nutrients, and/or microbial inocula to the contaminated zone. This review considers the fate and effects of hydrocarbon contaminants in terrestrial environments, with particular reference to the factors that limit biodegradation rates. The potential efficiencies, advantages, and disadvantages of biotreatment techniques are discussed and the future research directions necessary for process development are considered.

Biodegradation, Environmental↗

PubMed2003

Cleaning up with genomics: applying molecular biology to bioremediation.

Bioremediation has the potential to restore contaminated environments inexpensively yet effectively, but a lack of information about the factors controlling the growth and metabolism of microorganisms in polluted environments often limits its implementation. However, rapid advances in the understanding of bioremediation are on the horizon. Researchers now have the ability to culture microorganisms that are important in bioremediation and can evaluate their physiology using a combination of genome-enabled experimental and modelling techniques. In addition, new environmental genomic techniques offer the possibility for similar studies on as-yet-uncultured organisms. Combining models that can predict the activity of microorganisms that are involved in bioremediation with existing geochemical and hydrological models should transform bioremediation from a largely empirical practice into a science.

Bacteria↗

PubMed2003

A field test of electret ion chambers for environmental remediation verification.

In 1999, the State of Idaho INEEL Oversight Program performed a field test to determine if electret ion chambers could be used as a replacement to soil sampling in field survey releases at a remediated radioactively contaminated site. This study compared exposure rates measured using electret ion chambers with gamma spectroscopic analysis results of soil samples collected at the remediated site. Exposure rate measurements were made in 1999 using electret ion chambers at the same locations that INEEL Oversight Program sampled soil in 1998 following MARSSIM protocol. The waste site was divided into nine survey units based upon site history including previous site surveys and physical boundaries. Exposure rate measurements at the remediation site compared well with exposure rate measurements made at reference background locations used for routine environmental monitoring by the State of Idaho indicating that the remedial action met cleanup criteria. A poor correlation between exposure rate measurements and 137Cs concentrations and other discrepancies were observed during this study with respect to measurements made during the 1998 final site survey.

Biodegradation, Environmental↗

PubMed2003

Gemmatimonas aurantiaca gen. nov., sp. nov., a gram-negative, aerobic, polyphosphate-accumulating micro-organism, the first cultured representative of the new bacterial phylum Gemmatimonadetes phyl. nov.

A phylogenetically novel aerobic bacterium was isolated from an anaerobic-aerobic sequential batch reactor operated under enhanced biological phosphorus removal conditions for wastewater treatment. The isolation strategy used targeted slowly growing polyphosphate-accumulating bacteria by combining low-speed centrifugations and prolonged incubation on a low-nutrient medium. The isolate, designated strain T-27T, was a gram-negative, rod-shaped aerobe. Cells often appeared to divide by budding replication. Strain T-27T grew at 25-35 degrees C with an optimum growth temperature of 30 degrees C, whilst no growth was observed below 20 degrees C or above 37 degrees C within 20 days incubation. The pH range for growth was 6.5-9.5, with an optimum at pH 7.0. Strain T-27T was able to utilize a limited range of substrates, such as yeast extract, polypepton, succinate, acetate, gelatin and benzoate. Neisser staining was positive and 4,6-diamidino-2-phenylindole-stained cells displayed a yellow fluorescence, indicative of polyphosphate inclusions. Menaquinone 9 was the major respiratory quinone. The cellular fatty acids of the strain were mainly composed of iso-C15:0, C16:1 and C14:0. The G + C content of the genomic DNA was 66 mol%. Comparative analyses of 16S rRNA gene sequences indicated that strain T-27T belongs to candidate division BD (also called KS-B), a phylum-level lineage in the bacterial domain, to date comprised exclusively of environmental 16S rDNA clone sequences. Here, a new genus and species are proposed, Gemmatimonas aurantiaca (type strain T-27T=JCM 11422T=DSM 14586T) gen. nov., sp. nov., the first cultivated representative of the Gemmatimonadetes phyl. nov. Environmental sequence data indicate that this phylum is widespread in nature and has a phylogenetic breadth (19% 16S rDNA sequence divergence) that is greater than well-known phyla such as the Actinobacteria (18% divergence).

Base Composition↗

PubMed2004

The evolution of the phenylacetic acid degradation pathway in bacteria.

The phenylacetic acid (PhAc) degradation pathway becomes an interesting model for the catabolism of aromatic compounds. To determine the molecular basis for this environmentally important process, we did a phylogenic analysis based on the PhAc CoA ligase gene. It suggests that the PhAc CoA ligase genes are distributing widely and subject to frequent lateral gene transfer within and across bacterial phylum.

Bacteria↗

PubMed2002

[Advances in researches of environmental behavior of sulfonylurea herbicides in soil].

In this article, the environmental behavior of sulfonylurea herbicides in soil, which included absorption and de-sorption, degradation, resistance, mobility, and inhibition on soil enzyme activity, was reviewed, and the influences of some soil factors, such as pH, soil type, water content, and organic matter on their environmental behavior were also discussed. Distributed Reactivity Model for Sorption was used to explain the hysteretic behavior of sulfonylurea in soil, and the biotic and abiotic degradation mechanisms were summarized. Some prospects on their ecological toxicity, adsorption strength, and degradation model were also discussed.

Adsorption↗

PubMed2006

Bacterial pathways for degradation of nitroaromatics.

The last one hundred years have seen a massive expansion in the chemicals industry; however, with this progress came the concomitant pollution of the environment with a significant range of xenobiotics.Nitroaromatic compounds form one such category of novel environmental contaminants and are produced through a large number of industrial processes, most notably the pesticides, dyes and explosives industries. Whilst singly nitrated aromatic compounds are usually mineralised in the environment, multiply nitrated aromatics, such as the explosive 2,4,6-trinitrotoluene (TNT), are recalcitrant and highly toxic. The predominant route of biological transformation of aromatic compounds is oxidation; however, the presence of three electron-withdrawing nitro-groups around the ring prevents oxidation, rendering such compounds resistant to biodegradation. The subsequent accumulation of these contaminants has stimulated much research leading to the isolation of bacteria that possess, to varying extents, the ability to remediate explosives and other nitroaromatic pollutants.The extreme environments created by these toxic substances accelerate the evolutionary process and examples of bacteria that have conscripted metabolic enzymes for novel remediatory pathways are included. This Highlight ends with a discussion of the future of nitroaromatic bioremediation including engineering plants to express bacterial enzymes for use in bioremediation programs.

Bacteria↗

PubMed1995

Tracking microbial populations effective in reducing exposure.

Microbial ecology provides the link between basic biochemical and molecular studies on toxicity reduction by microbial metabolism and environmental studies that determine exposure. This link provides the ability to determine which microorganisms are responsible for the actual transformations in nature, thereby establishing how predictive the laboratory pathway, kinetic, regulatory, and enzyme mechanistic information is for nature. This information can be important to the rate of toxicant removal, the type and concentration of intermediate product(s), and the identification of conditions that limit effective toxicant removal. Nucleic acid-based methods now provide the main means to track important biodegrading populations. Examples of these methods are given that illustrate tracking a biodegrading microbe injected into an aquifer, following community succession in a toluene-degrading fluidized bed reactor, aiding the isolation from nature of novel biodegrading organisms, and rapidly characterizing the extent of microbial diversity in an aquifer stimulated to co-metabolize trichloroethene.

Biodegradation, Environmental↗

PubMed2000

Aromatic hydrocarbon dioxygenases in environmental biotechnology.

Aromatic hydrocarbon dioxygenases belong to a large family of Rieske non-heme iron oxygenases. The dioxygenases have a broad substrate specificity and catalyze enantiospecific reactions with a wide range of substrates. These characteristics make them attractive synthons for the production of industrially and medically important chiral chemicals and also provide essential information for the development of bioremediation technology.

Biodegradation, Environmental↗