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PubMed2002

Microbial detoxification of waste rubber material by wood-rotting fungi.

The extensive use of rubber products, mainly tires, and the difficulties to recycle those products, has resulted in world wide environmental problems. Microbial devulcanisation is a promising way to increase the recycling of rubber materials. One obstacle is that several microorganisms tested for devulcanisation are sensitive to rubber additives. A way to overcome this might be to detoxify the rubber material with fungi prior to the devulcanisation. In this study, 15 species of white-rot and brown-rot fungi have been screened with regard to their capacity to degrade an aromatic model compound in the presence of ground waste tire rubber. The most effective fungus, Resinicium bicolor, was used for detoxification of rubber material. Increase in growth of the desulfurising bacterium Thiobacillus ferrooxidans in presence of the rubber treated with Resinicium bicolor compared to untreated rubber demonstrated that detoxification with fungi is possible.

Anthraquinones↗

PubMed1997

First production-level bioremediation of explosives-contaminated soil in the United States.

Umatilla Army Depot Activity (UMDA) near Hermiston, Oregon was the location of the first production-level bioremediation of explosives-contaminated soil in the U.S. Soil from munitions washout lagoons contained high concentrations of TNT (2,4,6-Trinitrotoluene) and RDX (Hexahydro-1,3,5-trinitro-1,3,5- triazine) as well as HMX (Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine). In addition to these primary contaminants, laboratory tests were performed for Tetryl (Methyl-2,4,6-trinitrophenylnitramine), 4-Am-DNT (4-Amino-2,6-dinitrotoluene), 2-Am-DNT (2-Amino-4,6-dinitrotoluene), 2,4 DNT (2,4-Dinitrotoluene), 2,6 DNT (2,6-Dinitrotoluene), 1,3,5-TNB (1,3,5-Trinitrobenzene), 1,3,-DNB (1,3-Dinitrobenzene) and NB (Nitrobenzene) during the pilot-scale treatability tests. The clean-up goal established by the Record of Decision (ROD) was 30 mg/kg each for TNT and RDX. Degradation progress was monitored using immunoassay field screening Methods SW 846,4050 and 4051. Confirmational analysis consisted of EPA Method 8330. Treatment time on a 2,700 cubic yard batch (810 cubic yards of soil) was 10-12 days. A composting technique developed by the Army Environmental Center and implemented by Bioremediation Service, Inc., Portland, Oregon was used at the site. Agricultural waste products (or amendments including cow manure, chicken manure, potato waste, sawdust and alfalfa) were blended with the contaminated soil during treatment. Specialized soil turning equipment mixed the compost for optimum biological action and homogeneity. Homogeneity of the compost mix ensured rapid degradation of all contaminants. Physical and chemical properties were closely monitored to ensure that thermophilic bacteria played a dominant role in the degradation process. Nearly 5,000 cubic yards of soil have been successfully treated, and more than 70% of all analyses indicate non-detectable levels of both TNT and RDX. The U.S. Army Corps of Engineers estimates that over $2.6 million is being saved using bioremediation at Umatilla.

Azocines↗

PubMed2003

Landfarming operation of oily sludge in arid region--human health risk assessment.

Landfarming is becoming one of the most preferred treatment technologies for oily sludge disposal in the Arabian Gulf region in general, and in the Kingdom of Saudi Arabia in particular. This technology is considered to be, economical, energy efficient, and environmentally friendly with minimal residue disposal problems. Application of this technology in the region is simply based on the studies conducted in the United States of America and Europe. There have hardly been any scientific studies conducted to evaluate performance of landfarming technology under arid conditions. Recently, detailed field experimental study has been conducted to evaluate the degradation process and health risk issues in landfarming under arid conditions. The study observed volatilization as the main process of hydrocarbon degradation, which can cause significantly high concentration of airborne volatile organic compounds (VOCs) in the atmosphere leading to serious human health risk to the onsite workers. It is particularly true in the early phase of the landfarming process (first 2 months from initial loading). This paper elaborates these findings in detail.

Biodegradation, Environmental↗

PubMed1986

Long-chain alkylbenzenes: their analytical chemistry, environmental occurrence and fate.

Since ca. 1950 long-chain alkylbenzenes have been produced industrially for the synthesis of alkylbenzenesulfonates, the anionic surfactants most commonly used in commercial detergents. Prior to 1965 the alkylbenzenes were generated by Frieldel-Crafts alkylation of benzene with tetrapropylene. This reaction produces a complex assemblage of phenylalkanes (TABs) having highly branched side chains. Due to their stability, the TABs proved to be environmentally troublesome and were ultimately replaced (during the mid-1960s) by the linear alkylbenzenes (LABs). The LABs consist of a mixture of secondary phenylalkanes with linear alkyl side chains ranging in length from C10 to C14. Because of their unique structures and composition, these compounds are easily identified and measured in complex environmental samples. The linear alkylbenzenes are also found in municipal wastewaters where their presence is thought to result from the use of domestic and industrial detergents. Because they are synthetic and unlikely to occur in other significant inputs to coastal marine waters, long-chain alkylbenzenes have obvious potential as waste-specific molecular tracers. The presence of long-chain alkylbenzenes in sediment trap particulates and marine sediments collected near a major waste outfall system in southern California indicates that these hydrocarbons can survive exposure to an oxygenated water column during sedimentation. Whereas changes in the isomer composition of the LABs with depth in the sediments are suggestive of microbial alteration, the vertical distribution of the TABs and LABs can be used as a geochronological tool to reconstruct waste depositional histories.

Benzene Derivatives↗

PubMed2001

[Cloning and fusion expression of detoxifying gene in Escherichia coli].

In insects, esterases play an important role in the degradation of organophosphate (OP) and Carbamate (CB) insecticides. The ability of esterase B1 to degrading OP and CB insecticides opens broad prospect of using it in programs to the insecticide pollution. OPs can be detoxified by hydrolysis of their phosphoester bonds, pyrethroids and some OPs like malathion, by hydrolysis of their carboxylester bonds, and diverse carbamate insecticides, herbicides and fungicides by hydrolysis of amide or other similar bonds. Most of the candidate bioremediation enzymes identified to date have been hydrolases. In recent years, we have focused our work on the transfer of a detoxifying esterase B1 gene from mosquito into E. coli and explored the possibility of using the detoxified enzymes in environmental protection. 5' initial of esterase B1 cDNA was cloned by RT-PCR and sequenced consequently. After the combination of 5' initial and 3' terminal fragment of esterase B1 cDNA, the recombinant vector pET-ESTB1 was constructed and transformed into E. coli BL21. A 60 kD protein was induced by IPTG and its expression was temperature-dependent. After 12 h induction, the target protein occupied 27% of the total protein. A pure recombinant protein was obtained by purification, and was detected with 10% SDS-PAGE. The results showed that 22.1% of malathion was degraded by crude detoxification enzyme in 15 mins, demonstrated a high degradation property. This research provides a novel approach, which takes the advantages of eucaryotes for bioremediation of pesticide pollutions.

Biodegradation, Environmental↗

PubMed2005

Bioconversion of lignocellulosic waste from selected dumping sites in Dar es Salaam, Tanzania.

The poor management of solid wastes in Tanzania urban centers is a chronic problem that has increasingly become a source of environmental pollution. Bioconversion offers a cheap and safe method of not only disposing these wastes, but also it has the potential to convert lignocellulosic wastes into usable forms such as reducing sugars that could be used as food. This paper reports a preliminary study on the physical characteristics, acid pretreatment, saccharification by cellulase from Trichoderma reesei and fermentation by Saccharomyces cerevisiae of the lignocellulosic component of the solid wastes collected from various dumping sites located in Kinondoni Municipality, Dar es Salaam city. The results showed that overall, the lignocellulosic component constitute about 50% of solid wastes dumped in the study areas. Maximum production of reducing sugars was obtained after 6h of saccharification while highest concentrations of bioethanol were achieved after 48 h of fermentation. Microbial bioconversion of lignocellulose component yielded up to 21% bioethanol.

Biodegradation, Environmental↗

PubMed2004

Behavior of Chlorpyrifos-methyl in soil and sediment.

This research was carried out with the aim of obtaining information regarding the possible environmental impact of Chlorpyrifos-methyl, an organophosphoric insecticide used in agriculture for its phytoiatric action against Hemiptera, Lepidoptera, Coleoptera, and Diptera. Studies relating to the degradation kinetics of the insecticide in two soils and one sediment have shown a rapid degradation process in all three. The prevalent form of degradation would appear to be the chemical type, because the degradation kinetics in a sterile soil have not demonstrated that micro-organisms play a significant part. The adsorption isotherms showed that the insecticide has a greater affinity for the sediment (Kf=143) as opposed to the soils (Kf=65) and that the adsorption process is practically irreversible. Moreover, hydrolysis tests in buffered solutions at pH 4, 7, and 9 revealed that the molecule is particularly unstable with a basic pH.

Adsorption↗

PubMed2004

Environmental VOSCs--formation and degradation of dimethyl sulfide, methanethiol and related materials.

Volatile organic sulfur compounds (VOSCs) play a major role in the global sulfur cycle. Two components, dimethyl sulfide (DMS) and methanethiol (MT) are formed in large amounts by living systems (e.g. algae, bacteria, plants), particularly in marine environments. A major route to DMS is by action of a lyase enzyme on dimethylsulfoniopropionate (DMSP). DMSP has other roles, for instance as an osmoprotectant and cryoprotectant. Demethiolation of DMSP and other materials leads to MT. A major transport process is release of DMS from the oceans to the atmosphere. Oxidation of DMS in the atmosphere by hydroxyl and nitrate radicals produces many degradation products including CO2, COS, dimethyl sulfoxide, dimethyl sulfone, organic oxyacids of sulfur, and sulfate. These materials also have roles in biotic processes and there are complex metabolic interrelationships between some of them. This review emphasizes the chemical reactions of the organic sulfur cycle. For biotic reactions, details of relevant enzymes are provided when possible.

Atmosphere↗

PubMed1994

Theoretical analysis of in vivo macrophage adhesion and foreign body giant cell formation on strained poly(etherurethane urea) elastomers.

Quantitative description of foreign body giant cell (FBGC) formation on poly(etherurethane urea) (PEUU) surfaces as a function of time can conceivably predict the effects of polymer characteristics on cellular responses in vivo. In the present study, the formation of FBGCs on strained and unstrained PEUUs was quantified with two parameters: the density of adherent macrophages present initially that participate in FBGC formation (d(o)) and the rate constant for cell fusion (k); both kinetic parameters were used to calculate the time-dependent FBGC density (dfc). Relationships were sought between results of the cellular analysis and the extent of environmental stress cracking (ESC), as characterized by scanning electron microscopy. Surface degradation was semiquantified with percent light transmittance. The materials used were: base PEUU, base PEUU with 1% Santowhite antioxidant powder, base PEUU with 5% Methacrol 2138F antifume agent, and base PEUU with both 1% Santowhite and 5% Methacrol 2138F. A comparison of unstrained base PEUU with base PEUU strained to 400% elongation indicated that the rate of cell fusion, but not d(o) and dfc, increased in the presence of strain. In all strained samples, additives that strongly affected the ESC also influenced FBGC kinetic parameters. Strained PEUU containing Santowhite had the lowest d(o), the slowest rate of cell fusion, and lowest dfc, and the least incidence of ESC. The results suggest that the incidence of ESC in PEUU was decreased in the presence of Santowhite, which also lowered the number of adherent macrophages participating in FBGC formation, the rate of FBGC formation and the subsequent FBGC density. These studies also indicate that strain in PEUUs does not directly modulate the adherent macrophage and FBGC density. Further studies are necessary to delineate the relationship between PEUU strain and adherent macrophage and FBGC activation, which leads to the exocytosis of degrading agents and the observed incidence of biodegradation.

Animals↗

PubMed2005

Potential of Brassic rapa, Cannabis sativa, Helianthus annuus and Zea mays for phytoextraction of heavy metals from calcareous dredged sediment derived soils.

Remediation of soil pollution is one of the many current environmental challenges. Anthropogenic activity has resulted in the contamination of extended areas of land, the remediation of which is both invasive and expensive by conventional means. Phytoextraction of heavy metals from contaminated soils has the prospect of being a more economic in situ alternative. In addition, phytoextraction targets ecotoxicologically the most relevant soil fraction of these metals, i.e. the bioavailable fraction. Greenhouse experiments were carried out to evaluate the potential of four high biomass crop species in their potential for phytoextraction of heavy metals, with or without with the use of soil amendments (EDTA or EDDS). A calcareous dredged sediment derived surface soil, with high organic matter and clay content and moderate levels of heavy metal pollution, was used in the experiments. No growth depression was observed in EDTA or EDDS treated pots in comparison to untreated controls. Metal accumulation was considered to be low for phytoextraction purposes, despite the use of chelating agents. The low observed shoot concentrations of heavy metals were attributed to the low phytoavailability of heavy metals in this particular soil substrate. The mobilising effects induced by EDTA in the soil were found to be too long-lived for application as a soil amendment in phytoextraction. Although EDDS was found to be more biodegradable, higher effect half lives were observed than reported in literature or observed in previous experiments. These findings caution against the use of any amendment, biodegradable or otherwise, without proper investigation of its effects and the longevity thereof.

Biodegradation, Environmental↗

PubMed2001

Interactions of chromium with microorganisms and plants.

Chromium is a highly toxic non-essential metal for microorganisms and plants. Due to its widespread industrial use, chromium (Cr) has become a serious pollutant in diverse environmental settings. The hexavalent form of the metal, Cr(VI), is considered a more toxic species than the relatively innocuous and less mobile Cr(III) form. The presence of Cr in the environment has selected microbial and plant variants able to tolerate high levels of Cr compounds. The diverse Cr-resistance mechanisms displayed by microorganisms, and probably by plants, include biosorption, diminished accumulation, precipitation, reduction of Cr(VI) to Cr(III), and chromate efflux. Some of these systems have been proposed as potential biotechnological tools for the bioremediation of Cr pollution. In this review we summarize the interactions of bacteria, algae, fungi and plants with Cr and its compounds.

Amino Acid Sequence↗

PubMed1997

Environmental degradation of polyacrylamides. II. Effects of environmental (outdoor) exposure.

The environmental fate of a polyacrylamide thickening agent (PATA), formulated without and with a glyphosate-surfactant herbicide (GH), was examined under various environmental situations: formulation in surface water and ground water, volatility, and soil mobility. Environmental Fate of PATA in Surface Water and Ground Water: PATA was formulated at four concentrations in distilled-deionized water, three surface water samples, and two ground water samples, without and with a GH. Solutions were placed in glass bottles, covered with plastic wrap, and exposed to environmental (outdoor) conditions for 6 weeks. Acrylamide and ammonium concentration, pH, and bacterial and fungal populations were measured weekly. All solutions in this portion of the study had a homogeneous milky appearance but the conclusions of the study were nearly transparent. The results of this study suggest that polyacrylamide can degrade to acrylamide under environmental conditions. Statistically, there was no linear correlation between the various parameters measured. Volatility: PATA was formulated without and with GH. Each solution plus an acrylamide standard (positive control) was placed in a glass beaker and exposed to environmental (outdoor) conditions for 6 days. Acrylamide concentration, ammonium concentration, pH, and solution volume were measured daily. Acrylamide and ammonium concentrations increased during the study in all formulations, except when solutions evaporated to dryness. pH did not change greatly over the course of the study for these samples. Those solutions containing PATA had a homogeneous milky appearance but by the conclusions of the study were nearly transparent. This suggests a physical structural change in the polymer. Soil Mobility: PATA formulated with GH was also applied to soil columns and soil boxes containing sand, Eudora sandy loam, Eudora sandy clay, and Kohola silt loam. Acrylamide could be detected by Day 2 in all soil columns. Acrylamide could not be detected in the runoff of any of the soil boxes.

Acrylamides↗

PubMed2006

Biotreatment of groundwater contaminated with MTBE: interaction of common environmental co-contaminants.

Contamination of groundwater with the gasoline additive methyl tert-butyl ether (MTBE) is often accompanied by many aromatic components such as benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene (BTEX). In this study, a laboratory-scale biotrickling filter for groundwater treatment inoculated with a microbial consortium degrading MTBE was studied. Individual or mixtures of BTEX compounds were transiently loaded in combination with MTBE. The results indicated that single BTEX compound or BTEX mixtures inhibited MTBE degradation to varying degrees, but none of them completely repressed the metabolic degradation in the biotrickling filter. Tert-butyl alcohol (TBA), a frequent co-contaminant of MTBE had no inhibitory effect on MTBE degradation. The bacterial consortium was stable and showed promising capabilities to remove TBA, ethylbenzene and toluene, and partially degraded benzene and xylenes without significant lag time. The study suggests that it is feasible to deploy a mixed bacterial consortia to degrade MTBE, BTEX and TBA at the same time.

Bacteria↗

PubMed1992

Detoxification of polycyclic aromatic hydrocarbons by fungi.

The polycyclic aromatic hydrocarbons (PAHs) are a group of hazardous environmental pollutants, many of which are acutely toxic, mutagenic, or carcinogenic. A diverse group of fungi, including Aspergillus ochraceus, Cunninghamella elegans, Phanerochaete chrysosporium, Saccharomyces cerevisiae, and Syncephalastrum racemosum, have the ability to oxidize PAHs. The PAHs anthracene, benz[a]anthracene, benzo[a]pyrene, fluoranthene, fluorene, naphthalene, phenanthrene, and pyrene, as well as several methyl-, nitro-, and fluoro-substituted PAHs, are metabolized by one or more of these fungi. Unsubstituted PAHs are oxidized initially to arene oxides, trans-dihydrodiols, phenols, quinones, and tetralones. Phenols and trans-dihydrodiols may be further metabolized, and thus detoxified, by conjugation with sulfate, glucuronic acid, glucose, or xylose. Although dihydrodiol epoxides and other mutagenic and carcinogenic compounds have been detected as minor fungal metabolites of a few PAHs, most transformations performed by fungi reduce the mutagenicity and thus detoxify the PAHs.

Biodegradation, Environmental↗

PubMedDate not supplied

Development of cultures capable of reducing perchlorate and nitrate in high salt solutions.

An ion exchange process with biological perchlorate and nitrate destruction and reuse of spent regenerant brine has been proposed as an efficient and environmentally sound method to treat perchlorate-contaminated groundwater. A culture capable of reducing perchlorate and nitrate in spent ion exchange regenerant brine containing at least 30 g/L NaCl is needed for this to be feasible. A batch culture inoculated from activated sludge failed to acclimate to more than 15 g/L NaCl whether nitrate was present or not. A mixed culture inoculated from marine sediment was capable of simultaneously reducing 100mg/L perchlorate and denitrifying 500 mg/L nitrate within 5 h in a synthetic medium in the presence of 30 g/L NaCl. The growth conditions to maintain this culture in a healthy state required the addition of trace metals, Na2S, and phosphate. A second culture capable of removing 100 mg/L perchlorate from synthetic medium containing 60 g/L NaCl within 24 h was also developed.

Biodegradation, Environmental↗

PubMed2001

Denitrification with acrylamide by pure culture of bacteria isolated from acrylonitrile-butadiene-styrene resin manufactured wastewater treatment system.

Acrylamide is widely used in industrial applications as cement binder and solidification agent. Due to its carcinogenicity and toxicity, discharge of acrylamide to the natural water and soil systems may lead to an adverse environmental impact on water quality and thus endanger public health and welfare. This study attempts to isolate and identify the denitrifying bacteria, which utilize acrylamide as the substrate from the acrylonitrile-butadiene-styrene resin manufactured wastewater treatment system. The performance of the denitrifying bacteria for treating different initial acrylamide concentrations was also investigated under aerobic and anaerobic conditions. The test results indicated that the Pseudomonas stutzeri could remove acrylamide at concentrations below 440 mg/l under aerobic conditions. The acrylic acid and ammonia intermediates were used as carbon and nitrogen sources, respectively. However, P. stutzeri did not show the capability of metabolizing acrylonitrile under aerobic conditions. Furthermore, the P. stutzeri could utilize both acrylamide and acrylic acid in the presence of nitrate (denitrification) and acrylamide could be removed completely from the wastewater.

Acrylamide↗

PubMed2002

Transformation of [14C] trichloroethylene by poplar suspension cells.

Trichloroethylene (TCE) is one of the most prevalent environmental contaminants, and it poses an expensive remediation problem. Phytoremediation has been investigated as a potential tool for the removal of TCE from ground water and soil, and has shown promise in preliminary trials. However, the fate of TCE in plants is largely unknown. Radiolabel studies showed that once taken up and transformed, most of the TCE is incorporated into plant tissue as a non-volatile, un-extractable residue. We describe here an assay for TCE transformation by poplar suspension cells. Using this assay, it was shown that two different activities contribute to the fixation of TCE by poplar cells, one associated with cell walls and insoluble residues, the other associated with a high molecular weight, heat labile fraction of the cell extract. It appears that plant enzymes catalyze some of the transformations.

Biodegradation, Environmental↗

PubMed2005

A new concept linking observable stable isotope fractionation to transformation pathways of organic pollutants.

Measuring stable isotope fractionation of carbon, hydrogen, and other elements by Compound Specific Isotope Analysis (CSIA) is a new, innovative approach to assess organic pollutant degradation in the environment. Central to this concept is the Rayleigh equation which relates degradation-induced decreases in concentrations directly to concomitant changes in bulk (= average over the whole compound) isotope ratios. The extent of in situ transformation may therefore be inferred from measured isotope ratios in field samples, provided that an appropriate enrichment factor (epsilonbulk) is known. This epsilonbulk value, however, is usually only valid for a specific compound and for specific degradation conditions. Therefore, a direct comparison of epsilonbulk values for different compounds and for different types of reactions has in general not been feasible. In addition, it is often uncertain how robust and reproducible epsilonbulk values are and how confidently they can be used to quantify contaminant degradation in the field. To improve this situation and to achieve a more in-depth understanding, this critical review aims to relate fundamental insight about kinetic isotope effects (KIE) found in the physico(bio)chemical literature to apparent kinetic isotope effects (AKIE) derived from epsilonbulk values reported in environmentally oriented studies. Starting from basic rate laws, a quite general derivation of the Rayleigh equation is given, resulting in a novel set of simple equations that take into account the effects of (1) nonreacting positions and (2) intramolecular competition and that lead to position-specific AKIE values rather than bulk enrichment factors. Reevaluation of existing epsilonbulk literature values result in consistent ranges of AKIE values that generally are in good agreement with previously published data in the (bio)-chemical literature and are typical of certain degradation reactions (subscripts C and H indicate values for carbon and hydrogen): AKIEc = 1.01-1.03 and AKIEH = 2-23 for oxidation of C-H bonds; AKIEc = 1.03-1.07 for SN2-reactions; AKIEc = 1.02-1.03 for reductive cleavage of C-Cl bonds; AKIEc = 1.00-1.01 for C=C bond epoxidation; AKIEc = 1.02-1.03 for C=C bond oxidation by permanganate. Hence, the evaluation scheme presented bridges a gap between basic and environmental (bio)chemistry and provides insight into factors that control the magnitude of bulk isotope fractionation factors. It also serves as a basis to identify degradation pathways using isotope data. It is shown how such an analysis may be even possible in complex field situations and/or in cases where AKIE values are smaller than intrinsic KIE values, provided that isotope fractionation is measured for two elements simultaneously ("two-dimensional isotope analysis"). Finally, the procedure is used (1) to point outthe possibility of estimating approximate epsilonbulk values for new compounds and (2) to discuss the moderate, but non-negligible variability that may quite generally be associated with epsilonbulk values. Future research is suggested to better understand and take into account the various factors that may cause such variability.

Biochemical Phenomena↗