Abstract: With more and more plastics being employed in human lives and increasing pressure being placed on capacities available for plastic waste disposal, the need for biodegradable plastics and biodegradation of plastic wastes has assumed increasing importance in the last few years. This review looks at the technological advancement made in the development of more easily biodegradable plastics and the biodegradation of conventional plastics by microorganisms. Additives, such as pro-oxidants and starch, are applied in synthetic materials to modify and make plastics biodegradable. Recent research has shown that thermoplastics derived from polyolefins, traditionally considered resistant to biodegradation in ambient environment, are biodegraded following photo-degradation and chemical degradation. Thermoset plastics, such as aliphatic polyester and polyester polyurethane, are easily attacked by microorganisms directly because of the potential hydrolytic cleavage of ester or urethane bonds in their structures. Some microorganisms have been isolated to utilize polyurethane as a sole source of carbon and nitrogen source. Aliphatic-aromatic copolyesters have active commercial applications because of their good mechanical properties and biodegradability. Reviewing published and ongoing studies on plastic biodegradation, this paper attempts to make conclusions on potentially viable methods to reduce impacts of plastic waste on the environment.

Abstract: Analytical Chemistry.- In-situ Method for Analyzing the Long-Term Behavior of Particulate Metal Phases in Soils.- Analysis of Toxic Metals by Micro Total Analytical Systems (?TAS) with Chemiluminescence.- Diffuse Infrared Fourier Transform Spectroscopy in Environmental Chemistry.- Detection of Biomarkers of Pathogenic Bacteria by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry.- Multi-Isotopic Approach (15N, 13C, 34S, 18O and D) for Tracing Agriculture Contamination in Groundwater.- 2H and 18O Isotopic Study of Ground Waters under a Semi-Arid Climate.- 13C/12C Ratio in Peat Cores: Record of Past Climates.- Isotopic Composition of Cd in Terrestrial Materials: New Insights from a High-Precision, Double Spike Analytical Method.- Organic Petrology: A New Tool to Study Contaminants in Soils and Sediments.- The Comminution of Large Quantities of Wet Sediment for Analysis and Testing with Application to Dioxin-Contaminated Sediments from Lake Ontario.- Study on the Large Volume Stacking Using the EOF Pump (LVSEP) for Analysis of EDTA by Capillary Electrophoresis.- Toxic Metals.- A Framework for Interpretation and Prediction of the Effects of Natural Organic Matter Heterogeneity on Trace Metal Speciation in Aquatic Systems.- Binding Toxic Metals to New Calmodulin Peptides.- Leaching of Selected Elements from Coal Ash Dumping.- Storm-Driven Variability of Particulate Metal Concentrations in Streams of a Subtropical Watershed.- A Model for Predicting Heavy Metal Concentrations in Soils.- Phytoremediation of Thallium Contaminated Soils by Brassicaceae.- Mercury Recovery from Soils by Phytoremediation.- Effect of Cadmium and Humic Acids on Metal Accumulation in Plants.- Selection of Microorganisms for Bioremediation of Agricultural Soils Contaminated by Cadmium.- Electrodialytic Remediation of Heavy Metal Polluted Soil.- Electrodialytic Removal of Cu, Cr and As from Treated Wood.- Treatment of Wastewater Contaminated by Mercury by Adsorption on the Crandallite Mineral.- Low Cost Materials for Metal Uptake from Aqueous Solutions.- Removal of Copper(II) and Cadmium(II) from Water Using Roasted Coffee Beans.- Organic Pollutants.- Bioremediation for the Decolorization of Textile Dyes - A Review.- Degradation of the Indigo Carmine Dye by an Anaerobic Mixed Population.- Biodegradation of Benzothiazoles by Rhodococcus Bacteria Monitored by 1H Nuclear Magnetic Resonance (NMR).- Biotransformation of Nonylphenol Surfactants in Soils Amended with Contaminated Sewage Sludges.- Quantification of in-situ Trichloroethene Dilution versus Biodegradation Using a Novel Chloride Concentration Technique.- Anthropogenic Organic Contaminants Incorporated into the Non-Extractable Particulate Matter of Riverine Sediments from the Teltow Canal (Berlin).- Behaviour of Dioxin in Pig Adipocytes.- Control of Halogenated By-Products During Surface Water Potabilisation.- Organic Pollutants in Airborne Particulates of Algiers City Area.- A Reactive Transport Model for Air Pollutants.- Polycyclic Aromatic Compounds.- Analysis of High-Molecular-Weight Polycyclic Aromatic Hydrocarbons by Laser Desorption-Ionisation/Time-of-Flight Mass Spectrometry and Liquid Chromatography/Atmospheric Pressure Chemical Ionisation Mass Spectrometry.- Atmospheric Polycyclic Aromatic Hydrocarbons (PAHs) in Two French Alpine Valleys.- Evaluation of the Risk of PAHs and Dioxins Transfer to Humans via the Dairy Ruminant.- Polycyclic Aromatic Hydrocarbons (PAHs) Removal during Anaerobic and Aerobic Sludge Treatments.- Photodegradation of Pyrene on Solid Phase.- Degradation of Polycyclic Aromatic Hydrocarbons in Sewage Sludges by Fenton's Reagent.- Pesticides.- Pesticide Mobility Studied by Nuclear Magnetic Resonance.- Photo- and Biodegradation of Atrazine in the Presence of Soil Constituents.- Behaviour of Imidacloprid in Fields. Toxicity for Honey Bees.- Impact of a Sulfonylureic Herbicide on Growth of Photosynthetic and Non-Photosynthetic Protozoa.- Abiotic Degradation of the Herbicide Rimsulfuron on Minerals and Soil.- Binding of Endocrine Disrupters and Herbicide Metabolites to Soil Humic Substances.- Potential Exposure to Pesticides during Amateur Applications of Home and Garden Products.- Green Chemistry.- Carbon Dioxide, a Solvent and Synthon for Green Chemistry.- Mechanochemistry: An Old Technology with New Applications to Environmental Issues. Decontamination of Polychlorobiphenyl-Contaminated Soil by High-Energy Milling in the Solid State with Ternary Hydrides.- Development of a Bioreactor for Cometabolic Biodegradation of Gas-Phase Trichloroethylene.- Enhanced Solubilization of Organic Pollutants through Complexation by Cyclodextrins.- Chemical Samples Recycling: The MDPI Samples Preservation and Exchange Project.- Photodecomposition of Organic Compounds in Aqueous Solution in the Presence of Titania Catalysts.- Depollution of Waters Contaminated by Phenols and Chlorophenols Using Catalytic Hydrogenation.- Treatment of Wastewater Containing Dimethyl Sulfoxide (DMSO).- Productive Use of Agricultural Residues: Cements Obtained from Rice Hull Ash.- Ecotoxicology.- Environmental Metal Cation Stress and Oxidative Burst in Plants. A Review.- The LUX-FLUORO Test as a Rapid Bioassay for Environmental Pollutants.- Effects of Two Cyanotoxins, Microcystin-LR and Cylindrospermopsin, on Euglena gracilis.- A New Bioassay for Toxic Chemicals Using Green Paramecia, Paramecium bursaria.- Detection of Toxic Pollution in Waste Water by Short-Term Respirometry.- Environmental Biosensors Using Bioluminescent Bacteria.- Evaluation of Water-Borne Toxicity Using Bioluminescent Bacteria.- Bacteria-Degraders Based Microbial Sensors for the Detection of Surfactants and Organic Pollutants.- Study of Cr(VI) and Cd(II) Ions Toxicity Using the Microtox Bacterial Bioassay.- Cultured Human Cells as Biological Detectors for Assessing Environmental Toxicity.- Genotoxic Impact of 'Erika' Petroleum Fuel on Liver of the Fish Solea Solea.- Heavy-Metal Resistant Actinomycetes.

Abstract: The organochlorine pesticide Lindane is the gamma-isomer of hexachlorocyclohexane (HCH). Technical grade Lindane contains a mixture of HCH isomers which include not only gamma-HCH, but also large amounts of predominantly alpha-, beta- and delta-HCH. The physical properties and persistence of each isomer differ because of the different chlorine atom orientations on each molecule (axial or equatorial). However, all four isomers are considered toxic and recalcitrant worldwide pollutants. Biodegradation of HCH has been studied in soil, slurry and culture media but very little information exists on in situ bioremediation of the different isomers including Lindane itself, at full scale. Several soil microorganisms capable of degrading, and utilizing HCH as a carbon source, have been reported. In selected bacterial strains, the genes encoding the enzymes involved in the initial degradation of Lindane have been cloned, sequenced, expressed and the gene products characterized. HCH is biodegradable under both oxic and anoxic conditions, although mineralization is generally observed only in oxic systems. As is found for most organic compounds, HCH degradation in soil occurs at moderate temperatures and at near neutral pH. HCH biodegradation in soil has been reported at both low and high (saturated) moisture contents. Soil texture and organic matter appear to influence degradation presumably by sorption mechanisms and impact on moisture retention, bacterial growth and pH. Most studies report on the biodegradation of relatively low (< 500 mg/kg) concentrations of HCH in soil. Information on the effects of inorganic nutrients, organic carbon sources or other soil amendments is scattered and inconclusive. More in-depth assessments of amendment effects and evaluation of bioremediation protocols, on a large scale, using soil with high HCH concentrations, are needed.

Abstract: Xenobiotic biodegradation under anaerobic conditions such as in groundwater, sediment, landfill, sludge digesters and bioreactors has gained increasing attention over the last two decades. This review gives a broad overview of our current understanding of and recent advances in anaerobic biodegradation of five selected groups of xenobiotic compounds (petroleum hydrocarbons and fuel additives, nitroaromatic compounds and explosives, chlorinated aliphatic and aromatic compounds, pesticides, and surfactants). Significant advances have been made toward the isolation of bacterial cultures, elucidation of biochemical mechanisms, and laboratory and field scale applications for xenobiotic removal. For certain highly chlorinated hydrocarbons (e.g., tetrachlorethylene), anaerobic processes cannot be easily substituted with current aerobic processes. For petroleum hydrocarbons, although aerobic processes are generally used, anaerobic biodegradation is significant under certain circumstances (e.g., O2-depleted aquifers, oil spilled in marshes). For persistent compounds including polychlorinated biphenyls, dioxins, and DDT, anaerobic processes are slow for remedial application, but can be a significant long-term avenue for natural attenuation. In some cases, a sequential anaerobic-aerobic strategy is needed for total destruction of xenobiotic compounds. Several points for future research are also presented in this review.

Abstract: The potential biodegradation of crude oil was assessed based on the development of a fermentative process with a strain of Pseudomonas aeruginosa which produced 15.4 g/L rhamnolipids when cultured in a basal mineral medium using glycerol as a sole carbon source. However, neither cell growth nor rhamnolipid production was observed in the comparative culture system using crude oil as the sole carbon source instead. As rhamnolipid, an effective biosurfactant, has been reported to stimulate the biodegradation of hydrocarbons, 1 g/L glycerol or 0.22 g/L rhamnolipid was initially added into the medium to facilitate the biodegradation of crude oil. In both situations, more than 58% of crude oil was degraded and further converted into accumulated cell biomass and rhamnolipids. These results suggest that Pseudomonas aeruginosa could degrade most of crude oil with direct or indirect addition of rhamnolipid. And this conclusion was further supported by another adsorption experiment, where the adsorption capacity of crude oil by killed cell biomass was negligible in comparison with the biologic activities of live cell biomass.

Abstract: Two phase partitioning bioreactors (TPPBs) operate by partitioning toxic substrates to or from an aqueous, cell-containing phase by means of second immiscible phase. Uptake of toxic substrates by the second phase effectively reduces their concentration within the aqueous phase to sub-inhibitory levels, and transfer of molecules between the phases to maintain equilibrium results in the continual feeding of substrate based on the metabolic demand of the microorganisms. Conventionally, a single pure species of microorganism, and a pure organic solvent, have been used in TPPBs. The present work has demonstrated the benefits of using a mixed microbial population for the degradation of phenol in a TPPB that uses solid polymer beads (comprised of ethylene vinyl acetate, or EVA) as the second phase. Polymer modification via an increase in vinyl acetate concentration was also shown to increase phenol uptake. Microbial consortia were isolated from three biological sources and, based on an evaluation of their kinetic performance, a superior consortium was chosen that offered improved degradation when compared to a pure strain of Pseudomonas putida ATCC 11172. The new microbial consortium used within a TPPB was capable of degrading high concentrations of phenol (approximately 2000 mg l(-1)), with decreased lag time (10 h) and increased specific rate of phenol degradation (0.71 g phenol g(1) cell h). Investigation of the four-member consortium showed that it consisted of two Pseudomonas sp., and two Acinetobacter sp., and tests conducted upon the individual isolates, as well as paired organisms, confirmed the synergistic benefit of their existence within the consortium. The enhanced effects of the use of a microbial consortium now offer improved degradation of phenol, and open the possibility of the degradation of multiple toxic substrates via a polymer-mediated TPPB system.

Abstract: This study was designed to examine the role of molecular structure in determining the biodegradation rates of polycyclic aromatic hydrocarbons (PAHs). Laboratory experiments were performed in aqueous systems, and data were analyzed in a manner that allowed determination of first-order biodegradation rates independent of bioavailability limitations from physical-chemical processes. An aerobic mixed culture was used, which had been enriched on a broad range of PAHs. The 22 PAHs included in this study ranged in size from two to four rings and included compounds with 5-carbon rings and alkyl substituents. The range of observed biodegradation rates was only 1 order of magnitude, which is much less than that which is typically observed in the field. This supports the findings of other types of studies, which conclude that most of the observed variation in environmental PAH biodegradation rates comes from processes controlling the bioavailability of the compounds and not processes controlling uptake or biotransformation. Rate differences that were observed were attributable either to the presence of a 5-carbon ring or an alkyl substituent in an alpha position. Various molecular descriptors that might be expected to correlate with rate-limiting steps in the biodegradation process were used in an attemptto develop a quantitative structure-activity relationship for the PAH biodegradation rates. No significant correlations were found, but rate limitation from interactions with the relevant enzymes remains a possibility.

Abstract: Ten sulfonated aromatic amines were tested for their aerobic and anaerobic biodegradability and toxicity potential in a variety of environmental inocula. Of all the compounds tested, only two aminobenzenesulfonic acid (ABS) isomers, 2- and 4-ABS, were degraded. The observed degradation occurred only under aerobic conditions with inocula sources that were historically polluted with sulfonated aromatic amines. Bioreactor experiments, with non-sterile synthetic wastewater, confirmed the results from the aerobic batch degradation experiments. Both ABS isomers were degraded in long-term continuous experiment by a bioaugmented enrichment culture. The maximum degradation rate in the aerobic bioreactor was 1.6-1.8 g 1(-1) d(-1) for 2-ABS and a somewhat lower value for 4-ABS at hydraulic retention times (HRT) of 2.8-3.3 h. Evidence for extensive mineralization of 2- and 4-ABS was based on oxygen uptake and carbon dioxide production during the batch experiments and the high levels of chemical oxygen demand (COD) removal in the bioreactor. Furthermore, mineralization of the sulfonate group was demonstrated by high recovery of sulfate. The sulfonated aromatic amines did not show any toxic effects on the aerobic and anaerobic bacterial populations tested. The poor biodegradability of sulfonated aromatic amines indicated under the laboratory conditions of this study suggests that these compounds may not be adequately removed during biological wastewater treatment.

Abstract: Microbial communities were characterized during biodegradation of immobilized oil in seawater from the Statfjord field and the German Bight in the North Sea. Seawater samples were collected at different distances from pollution sources at the two locations. A Statfjord oil was immobilized on hydrophobic synthetic Fluortex fabrics and submerged in closed flasks (no headspace) with natural or sterile seawater and incubated at 13°C for 56 days. Biodegradation of immobilized n-alkanes was measured by gas chromatography, total microbes were enumerated by epifluorescence microscopy, and culturable heterotrophic and oil-degrading microorganisms were quantified by most probable number (MPN) analysis. Polymerase chain reaction (PCR) amplification of bacterial 16S rDNA in water samples was conducted during biodegradation experiments. The amplified 16S rDNA fragments were characterized by denaturing gradient gel electrophoresis (DGGE), and by sequence analysis of cloned inserts. Biodegradation rates of alkanes in seawater collected at different distances from the pollution sources did not differ significantly (P > 0.05). Concentrations of oil-degrading microorganisms showed a temporary peak after 7 days of degradation, with a subsequent decline later in the period. DGGE analysis of 16S rRNA genes showed that community diversity decreased during the first 2–3 weeks of biodegradation, with the emergence of a few dominant bands. Cloning, restriction analysis, and sequence analysis of the 16S rDNA fragments revealed >30 different phylotypes. Abundant types during biodegradation belonged to the α-Proteobacteria, in waters from both Statfjord and the German Bight. Cloning and sequencing studies indicated that the most abundant bacteria during biodegradation belonged to the family Rhodobacteraceae, with the closest relationship to the genera Sulfitobacter and Roseobacter.

Abstract: The biodegradation of poly(butylene succi- nate) (PBS) was studied under controlled composting con- ditions. The ultimate biodegradation percentage revealed that the powder-formed sample showing the best biode- gradability may be ascribed to the largest specific surface. The biodegradation process of PBS under controlled com- posting conditions exhibited three phases. The biodegrada- tion in the first phase was slow, got accelerated in the second phase, and showed a leveling-off in the third phase. The degradation of PBS film after composting was further char- acterized by gel permeation chromatography (GPC) and scanning electron microscopy (SEM). Four strains were iso- lated from the compost and identified as Aspergillus versi- color, Penicillium, Bacillus, and Thermopolyspora. Their de- grading abilities to PBS powder in liquid medium were different. Among them, Aspergillus versicolor was the best PBS-degrading microorganism. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2273-2278, 2005

Abstract: This study investigated the use of an aqueous hydroxypropyl-p-cyclodextrin (HPCD) shake extraction to predict the degree of microbial degradation of polycyclic aromatic hydrocarbons (PAHs) in soils. Three different aged PAH-contaminated soils were studied: A soil from a former coke works (CW) and two artificially contaminated soils (ACI and AC2). First, the catabolic activity of the indigenous soil microflora was assessed with C-14-respirometry, using a range of C-14- labeled aromatic compounds. Extensive mineralization of several compounds occurred in the CW and the AC2 soils, suggesting that both soils contained catabolically active microorganisms. No significant mineralization occurred in the ACI soil, implying that either it did not contain an indigenous PAH-degrading microbial population or that degradation, but not mineralization, occurred. The soils then were subjected to three sets of analyses: dichloromethane (DCM) soxhlet extraction, six-week biodegradation assay followed by DCM extraction, and extraction with HPCD followed by DCM extraction. A general decrease in PAHs present in the soils occurred after the biodegradation assay. In the CW and the AC1 soils, strong correlations were observed between the amount of PAHs biodegraded and the fraction of PAHs removed from the soils using the HPCD extraction. However, the AC2 soil showed a more modest correlation between the biodegradable fraction and the HPCD extractable fraction, with the HPCD extraction slightly underestimating the extent of PAH biodegradation. The results of this study indicated that an aqueous HPCD extraction may be a useful tool in assessing the microbial availability of aged contaminant mixtures in soils, although further validation is required.

Abstract: In vitro biodegradation of the Prestige heavy fuel oil has been carried out using two microbial consortia obtained by enrichment in different substrates to simulate its environmental fate and potential utility for bioremediation. Different conditions, such as incubation time (i.e., 20 or 40 d), oil weathering, and addition of an oleophilic fertilizer (S200), were evaluated. Weathering slowed down the degradation of the fuel oil, probably because of the loss of lower and more labile components, but the addition of S200 enhanced significantly the extension of the biodegradation. n-Alkanes, alkylcyclohexanes, alkylbenzenes, and the two- to three-ring polycyclic aromatic hydrocarbons (PAHs) were degraded in 20 or 40 d of incubation of the original oil, whereas the biodegradation efficiency decreased for higher PAHs and with the increase of alkylation. Molecular markers were degraded according to the following sequence: Acyclic isoprenoids > diasteranes > C27-steranes > betabeta-steranes > homohopanes > monoaromatic steranes > triaromatic steranes. Isomeric selectivity was observed within the C1- and C2-phenanthrenes, dibenzothiophenes, pyrenes, and chrysenes, providing source and weathering indices for the characterization of the heavy oil spill. Acyclic isoprenoids, C27-steranes, C1- and C2-naphthalenes, phenanthrenes, and dibenzothiophenes were degraded completely when S200 was used. The ratios of the C2- and C3-alkyl homologues of fluoranthene/pyrene and chrysene/benzo[a]anthracene are proposed as source ratios in moderately degraded oils. The 4-methylpyrene and 3-methylchrysene were refractory enough to serve as conserved internal markers in assessing the degradation of the aromatic fraction in a manner similar to that of hopane, as used for the aliphatic fraction.

Abstract: Exhaustive studies on the degradation of plastics have been carried out in order to overcome the environmental problems associated with synthetic plastic waste. Recent work has included studies of the distribution of synthetic polymer-degrading microorganisms in the environment, the isolation of new microorganisms for biodegradation, the discovery of new degradation enzymes, and the cloning of genes for synthetic polymer-degrading enzymes. Under ambient conditions, polymers are known to undergo degradation, which results in the deterioration of polymer properties, characterized by change in its molecular weight and other physical properties. In this paper mainly the biodegradation of synthetic polymers such as polyethers, polyesters, polycaprolactones, polylactides, polylactic acid, polyurethane, PVA, nylon, polycarbonate, polyimide, polyacrylamide, polyamide, PTFE and ABS have been reviewed. Pseudomonas species degrade polyethers, polyesters, PVA, polyimides and PUR effectively. No microorganism has been found to degrade polyethylene without additives such as starch. None of the biodegradable techniques has become mature enough to become a technology yet.