Abstract: A wide variety of different types of microorganisms are known to produce intracellular energy and carbon storage products which have been generally described as being poly(β-hydroxybutyrate), PHB, but which are, more often than not, copolymers containing different alkyl groups at the β-position. Hence, PHB belongs to the family of poly(β-hydroxyalkanoates), PHA, all of which are usually formed as intracellular inclusions under unbalanced growth conditions. Recently, it became of industrial interest to evaluate PHA polyesters as natural, biodegradable, and biocompatible plastics for a wide range of possible applications such as surgical sutures or packaging containers. For industrial applications, the controlled incorporation of repeating units with different chain lengths into a series of copolymers is desirable in order to produce polyesters with a range of material properties because physical and chemical characteristics depend strongly on the polymer composition. Such “tailormade” copolymers can be produced under controlled growth conditions, in that if a defined mixture of substrates for a certain type of microorganisms is supplied, a well defined and reproducible copolymer is formed.

Abstract: Almost half of the biomass synthesized by photosynthetic fixation of carbon dioxide is made up of cellulose. Cotton and wood fibers are the most common sources. It makes up for about 90% of cotton fibers but for only about 45% of the average wood fiber.

Abstract: Pesticides in the Soil Microbial Ecosystems Effects of Long-Term Phenoxyalkanoic Acid Herbicide Field Applications on the Rate of Microbial Degradation Enhanced Carbamothioate Herbicide Degradation: Research in Nebraska Enhanced Biodegradation of Carbamothioate Herbicides in South Carolina Enhanced Biodegradation of Dicarboximide Fungicides in Soil Enhanced Biodegradation of Insecticides in Midwestern Corn Soils Enhanced Degradation of Insecticides in Soil: Factors Influencing the Development and Effects of Enhanced Microbial Activity Enhanced Degradation of S-Ethyl N,N-Dipropylcarbamothioate in Soil by an Isolated Soil Microorgnism The Role of Fungi and Bacteria in the Enhanced Degradation of Fungicide Carbendazim and the Herbicide Diphenamid Influence of Pesticide Metabolites on the Development of Enhanced Biodegradation Molecular Genetics of Pesticide Degradation by Soil Bacteria Response of Microbial Populations to Carbofuran in Soils Enhanced for Its Degradation Adaptation of Microorganisms in Subsurface Environments and its Significance to Pesticide Degradation Microbial Adaptation in Aquatic Ecosystems Evaluation of Some Methods for Coping with Enhanced Biodegradation of Soil Insecticides Systems Allowing Continued Use of Carbmothioate Herbicides Despite Enhanced Biodegradation Cultural Practices and Chemicals That Affect the Persistence of Carbamothioate Herbicides in Soil Spectrophotometric Methodologies for Predicting and Studying Enhanced Degradation Enhancing Biodegradation for Detoxification of Herbicide Waste in Soil Implications of Enhanced Biodegradation for the Use and Study of Pesticides in the Soil Environment

Abstract: An archaebacterium (strain EH4) able to biodegrade saturated and aromatic hydrocarbons has been isolated from a sail-marsh. Maximum growth on eicosane (62% of biodegradation, 10 h generation time) was reached in a medium prepared with a natural hypersaline water collected from a salt-marsh (3.5 mol/1 NaCl concentration). No growth on hydrocarbons was observed for NaCl concentration lower than 1.8 mol/1.

Abstract: Biotechnology and biodegradation , Biotechnology and biodegradation , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Abstract: Studies were conducted to examine the biodegradation of 14C-labeled vinyl chloride in samples taken from a shallow aquifer. Under aerobic conditions, vinyl chloride was readily degraded, with greater than 99% of the labeled material being degraded after 108 days and approximately 65% being mineralized to 14CO2.

Abstract: Three species of nitrifying bacteria were tested for the ability to degrade the halocarbon fumigants methyl bromide, 1,2-dichloropropane, and 1,2-dibromo-3-chloropropane. The soil nitrifiers Nitrosomonas europaea and Nitrosolobus multiformis degraded all three fumigants, while the marine nitrifier Nitrosococcus oceanus degraded only methyl bromide under the conditions tested. Inhibition of biodegradation by allylthiourea and acetylene, specific inhibitors of ammonia monooxygenase, suggests that ammonia monooxygenase is the enzyme which catalyzes fumigant degradation.

Abstract: Degradability of Commodity Plastics and Specialty Polymers: An Overview Biodegradative Processes and Biological Waste Treatment: Analysis and Control Insect Symbionts: A Promising Source of Detoxifying Enzymes Plastics Recycling Efforts Spurred by Concerns About Solid Waste Plastic Degradability and Agricultural Product Utilization Polyethylene Degradation and Degradation Products Biodegradation of Starch-Containing Plastics Constraints on Decay of Polysaccharide-Plastic Blends Biodegradaton Pathways of Nonionic Ethoxylates: Influence of the Hydrophobe Structure Biodegradation of Polyethers Biodegradable Poly(carboxylic acid) Design Biodegradation of Synthetic Polymers Containing Ester Bonds Biodegradable Polymers Produced by Free-Radical Ring-Opening Polymerization In Vitro and In Vivo Degradation of Poly(L-lactide) Braided Multifilament Yarns Biodegradable Fibers of a p-Dioxonone Copolymers Monomers and Polymers Based on Mono- and Disaccharides Polymers and Oligomers Containing Furan Rings Microbial Fructan: Production and Characterization Coatings Based on Brassylic Acid (An Erucic Acid Derivative) Synthesis and Characterization of Chlorinated Rubber from Low-Molecular-Weight Guayule Rubber Chemical Modification of Lignocellulosic Fibers to Produce High-Performance Composites Cellulose and Cellulose Derivatives as Liquid Crystals Specialty Starches: Use in the Paper Industry Saponified Starch-g-poly(acrylonitrile-co-2-acrlamido-2-methylpropanesul fonicacid): Influence of Reaction Variables on Absorbency and Wicking Use of Hemicelluloses and Cellulose and Degradation of Lignin by Pleurotus sajor-caju Grown on Corn Stalks

Abstract: 1,1,1-Trichloroethane was readily degraded in samples from an alluvial aquifer under both methanogenic and sulfate reducing conditions. No lag period was noted prior to disappearance of the parent compound. Products detected in the reaction mixtures included 1,1-dichloroethane, chloroethane, 1,1-dichloroethene, acetic acid and carbon dioxide. No other chlorinated metabolites were detected. Biological reductive dehalogenation was responsible for the metabolism of 1,1,1-trichloroethane to 1,1-dichloroethane and to chloroethane. Abiotic transformations resulted in 1,1-dichloroethene and acetic acid. However, biological mechanisms also appeared to contribute to the formation of acetic acid, which was subsequently mineralized to carbon dioxide. Pseudofirst-order rate constants estimated for the biotransformation of 1,1,1-trichloroethane were in the range of 0.0034 day−1 to 0.015 day−1, whereas the rate constant for abiotic degradation was approximately 0.0006 day−1. Biotransformation of the compound was not observed in aquifer samples under aerobic or denitrifying conditions.

Abstract: Ground water in the immediate vicinity of an area previously used for the disposal of charcoal manufacturing wastes has been shown to contain low levels of phenolic and polycyclic compounds. Based on the analysis of samples obtained from monitoring wells, the levels of the organic contaminants are reduced to near or below the detection limit within a distance of 100 meters downgradient of the fill. Examination of the ground-water chemistry indicated that the aquifer is essentially aerobic across the site, except in the immediate vicinity of the fill. At this point, dissolved oxygen is apparently depleted due to the biodegradation of organic contaminants introduced into the ground water, with a concomitant increase in the inorganic carbon concentration. Laboratory microcosm experiments demonstrated that the naturally occurring microorganisms can readily degrade a mixture of the predominant organic contaminants. Half-lives for biodegradation were in the range of 3 to 8 days for phenolic substrates, and 11 to 18 days for naphthalene. Computer model simulations indicated that the attenuation observed in the aquifer cannot be explained in terms of physical processes such as adsorption or dispersion, but is consistent with biological degradation.

Abstract: An obligately anaerobic bacterium known as strain DCB-1 was grown under a variety of conditions to determine the requirements for dehalogenation as well as factors which stimulated or inhibited the process. Dechlorination was obligately anaerobic since introduction of O2 immediately inhibited the reaction. Sulfuroxy anions, which also serve as electron acceptors for DCB-1, inhibited dechlorination but NO3 − and fumarate did not. The optimum growth medium for dechlorination was 0.2% Na pyruvate and 20% rumen fluid in basal salts. Media with either pyruvate or rumen fluid alone did not support dechlorination. DCB-1 also consumed H2 but typical substrate concentrations of H2 (80 kPa) delayed dechlorination. Once the H2 concentration was reduced to <20 μM (2.67 kPa), dechlorination resumed. Dehalogenation by DCB-1 was restricted to the meta substituted benzoates as halogens in other positions and chloroaromatic compounds with other functional groups were not dechlorinated.

Abstract: Wastewaters from deing and finishing processes contain a large amount of organic substances such as thickening agents as well as dyes. It is expected to develop a wastewater clarification technology for removing the dyes and the other organic substances in a single operation by use of the dye assimilating bacteria. The model wastewater was treated, by a rotating biological contactor with disk on which Pseudomonas cepacia 13N was immobilized with k-carrageenan gel

Abstract: To study mechanisms by which microorganisms oxidize thiophenic sulfur in coal, we tested bacterial cultures for the ability to degrade dibenzothiophene (DBT), DBT-5-oxide, and DBT-sulfone and to modify water-soluble coal products derived from Illinois no. 6 and Ugljevik coals. In yeast extract medium, the majority of selected isolates degraded DBT and accumulated DBT-5-oxide in culture fluids; all but one of the cultures degraded DBT-5-oxide, and none of them degraded DBT-sulfone. Elemental analysis data indicated that the microbial cultures were able to decrease the amount of sulfur in soluble coal products derived from Illinois no. 6 and Ugljevik coals. However, these data suggested that microbially mediated sulfur removal from soluble Ugljevik coal occurred by nonspecific mechanisms. That is, extensive degradation of the carbon structure was concurrent with the loss of sulfur. This conclusion was supported by X-ray photoelectron spectroscopic data which indicated that the reduced sulfur forms in the soluble Ugljevik coal product was not oxidized by microbial treatment.

Abstract: Three different types of biodegradable copolyesters were produced from various carbon substrates in a batch culture of Alcaligenes eutrophus. A random copolymer of 3-hydroxybutyrate and 3-hydroxypropionate, P(3HB-co-3HP), was produced in a nitrogen-free culture solution of 3-hydroxypropionic acid, 1,5-pentanediol, 1,7-heptanediol, or 1,9-nonanediol. The copolyester of 3-hydroxybutyrate and 4-hydroxybutyrate, P(3HB-co-4HB), was produced from various carbon sources such as 4-hydroxybutyric acid, γ-butyrolactone, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, and 1,12-dodecanediol. The copolyester of 3-hydroxybutyrate and 3-hydroxyvalerate, P(3HB-co-3HV), was produced from propionic or pentanoic acid. The pathway of poly(hydroxyalkanoates), (PHA) metabolism in A.eutrophus has been discussed. The biodegradability of PHA films was studied in the aqueous solution of extracellular PHA depolymerase purified from A.faecalis. The presence of 3HP and 4HB units in the P(3HB) sequence accelerated the rate of enzymatic degradation, whereas the presence of 3HV units retarded the degradation rate of polyester.

Abstract: The enhanced biotransformation of vinyl chloride (VC) under anaerobic conditions was studied using static microcosms and a flow-through column packed with soil from a study site. Vinyl chloride was found to be resistant to transformation in the static microcosms in five months of incubation; however, 89% of the vinyl chloride that was dissolved in the water was transformed when the microbiota in the columns was stimulated with a mixture of nutrients. In the presence of nutrients such as methane, methanol, ammonium phosphate and phenol, the main products of biotransformation were nonchlorinated organics such as methane and ethylene. Sodium acetate, added to the water and soil, did not enhance the biotransformation of VC because acetate-utilizing bacteria were not found at the study site and none developed in soil sample after the 21 d allowed for adaptation. Four biodegradation mechanisms of vinyl chloride under anaerobic conditions were recognized in this study: (a) reductive dechlorination to ethylene; (b) mineralization to methane; (c) formation of chloromethane, probably followed by methane formation; and (d) bio-oxidation to CO2, where acetate and citrate were added. A pseudo-first-order rate constant of 1.01 × 10−3 months−1 and a t1/2 of 57.2 years were calculated for the disappearance of vinyl chloride in soil and water microcosms under anaerobic conditions, without bioenhancement.

Abstract: Biodegradation and adsorption of natural organic matter (NOM) were studied in a laboratory-scale GAC reactor. Ozonation was found to encourage biofilm growth and biodegradation of NOM. Biofilm organisms grown on ozonated NOM readily degraded trace concentrations of phenol

Abstract: The microbial release of 14 C-labeled 2,4-dichlorophenol (DCP) bound to synthetic and natural humic materials or polymerized by enzymes was investigated to evaluate the possibility of future adverse effects if binding or polymerization is used for decontamination purposes. After 12 wk of incubation with microorganisms obtained from a forest soil, the amounts of substances released into the media were very small (maximum 2.2% of the initially bound 14 C) without regard to the kind of the polymer into which 14 C-DCP was incorporated

Abstract: The biodegradability of ten paper mill wastewater constituents under methanogenic conditions was evaluated in this study. The compounds studied included wood resin constituents and low molecular weight lignin derivatives. Biodegradation was assessed in batch bioassays inoculated with anaerobic granular sludge at 30 ± 2°C. The assays were supplied with low concentrations of the test chemicals (35–200 mg 1−1) to prevent methanogenic inhibition. The long chain fatty acids, oleic and linoleic acid, were readily biodegradable under anaerobic conditions. Guaiacol was also mineralized after a 40 days lag period. However, no indication of methanogenic degradation was obtained with eugenol, benzene, the resin acids (abietic and dehydroabietic acid), the volatile terpenes (pinene and limonene) and the unsaturated hydrocarbon squalene.

Abstract: The effects of temperature, dissolved oxygen, and other environmental parameters under both aerobic and anaerobic conditions were investigated using one aerobic and one facultative strain isolated from wastewater treatment plant sludge. Among other results, we found that low dissolved oxygen levels and low temperatures decreased the rate of DEP degradation and the growth rate, and that the facultative strain was much less affected by the lower DO concentrations than the aerobic strain.

Abstract: We examined the ability of native microorganisms in various Idaho soils to degrade dinoseb and studied some physical and chemical soil characteristics which might affect the biodegradation process. Dinoseb biodegradation rates were higher in silt-loam soils than in loamy-sand soils. Biodegradation rates were not influenced by previous exposure of the soils to dinoseb. Bacterial numbers, measured by standard plate counts on soil extract agar, were the best predictors of biodegradation rates, accounting for 53% of the variability between soils. Soil nitrate-N inhibited dinoseb biodegradation and accounted for 39% of the variability. Sorption of dinoseb to soil surfaces also appeared to influence biodegradation rates. No other soil parameter contributed significantly to the variability in biodegradation rates. Persistence of dinoseb in one soil was due to inhibition of biodegradation by nitrate, while in another soil persistence appeared to be due to lack of native degradative microorganisms.

Abstract: Low-molecular-weight halogenated hydrocarbons are susceptible to degradation by anaerobic and aerobic bacteria. The methanotrophic bacterium Methylosinus trichosporium 0B3b degrades trichloroethylene more rapidly than other bacteria examined to date. Expression of soluble methane monooxygenase (MMO) is correlated with high rates of biodegradation. An analysis of 16 S rRNA sequences of 11 ribosomal RNAs from type I, type II and type X methanotrophs and methanol-utilizing bacteria have revealed four clusters of phylogenetically related methylotrophs. This information may be useful for the identification and enumeration of methylotrophs in bioreactors and other environments during remediation of contaminated waters.