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The Passaic River in New Jersey, USA is heavily polluted by chlorodibenzo-p-dioxins (CDDs). Highly chlorinated CDDs are dechlorinated by anaerobic bacteria from these sediments, producing lightly chlorinated or even non-chlorinated dibenzo-p-dioxin (DD) daughter products. Surficial Passaic River sediments were enriched under aerobic conditions and three bacterial strains (PR1, PR2 and PR3) were isolated using dibenzofuran (DF) as a model substrate. PR1 is closely related to Janibacter terrae (99.4%), a known CDD and DD degrader. PR2 and PR3 are closely related to Agromyces mediolanus (99.2%) and Arthrobacter oryzae (99.5%), respectively, which are genera not known to degrade CDDs. Janibacter PR1 grew more rapidly on DF than PR2 and PR3. The less well characterized PR2 and PR3 both degraded DD and 2-monochlorodibenzo-p-dioxin (2MCDD), at similar rates. Neither PR2 nor PR3 transformed 2,7-dichlodibenzo-p-dioxin (2,7DCDD). An angular dioxygenase 99.7% identical to that in Terrabacter sp. DBF63 was detected by PCR in Janibacter PR1 and Agromyces PR2. PCR did not detect an angular dioxygenase in Arthrobacter PR3. In this work, novel aerobic bacterial strains that can aerobically degrade the products of dechlorination were identified in surficial Passaic River sediments. The presence of these bacteria could enable an in situ treatment process that completely removes all CDDs from the sediment. [ABSTRACT FROM AUTHOR]

The objective of this study was to construct a microbial consortium for effective biodegradation of chlorpyrifos (CP) and its hydrolysis product, 3,5,6-Trichloro-2-pyridinol (TCP). A activated sludge from an organophosphorus pesticide factory was domesticated under long-term (20 weeks) CP stress, and the dynamic change in bacterial communities was analyzed by high-throughput sequencing. Then, a microbial consortium MC-BSPK was constructed of Bacillus sp. MC-B, Serratia sp. MC-S, Pseudomonas sp. MC-P, and Klebsiella sp. MC-K, which were significantly enriched during the domestication process. The biodegradation capacities of the microbial consortium MC-BSPK reached 100% for CP within 9 days and 88.61% for TCP within 15 days under the optimized degradation conditions (pH 8.0 and 31 °C). High-performance liquid chromatography (HPLC) revealed that CP could be degraded by the microbial consortium MC-BSPK into TCP, probably through hydrolysis of the P–O ester bond, and further degraded into other small molecules. A bioassay revealed that the virulence of CP toward Drosophila melanogaster W1118 was clearly reduced by the microbial consortium MC-BSPK biodegradation. Thus, the easily constructed microbial consortium MC-BSPK with high CP/TCP degradation capacities has the potential for application in pesticide-contaminated bioremediation. [ABSTRACT FROM AUTHOR]

Enriched microorganisms in sediment collected from a dioxin-contaminated site in Vietnam (Bien Hoa airbase) were used for examining the effectiveness in biological treatment of 2,3,7,8-Tetrachlorodibenzo-p-dioxin in soil. Four bio-treatments were investigated using a sequential anaerobic (17 weeks) followed by an aerobic (6 weeks) incubation. The maximum removal efficiency was approximately 60% even at an extremely low pH (approx. 3.6) condition. Surfactant Tween-80 was added to enhance the bioavailability of dioxin in two treatments, but it appeared to biostimulate methanogens rather than dechlorinators. As a result, methane production was the highest while the dioxin removal efficiency was the lowest, as compared with the other bio-treatments. Carboxymethylcellulose (CMC) coated on nanoscale zero valent iron (nZVI) surface used in two treatments could prevent the direct contact between bacterial cell surface and nZVI which prevented cell death and lysis, hence enhancing dioxin removal. The presence of CMC­­_nZVI in bio-treatments gradually released H2required for microbiological processes, but the amount used in the experiments were likely too high to maintain optimum H2levels for biostimulating dechlorinators rather than methanogens. [ABSTRACT FROM PUBLISHER]

Polyhydroxyalkanoates (PHAs) have been demonstrated to be a family of biopolymers with good biodegradability and biocompatibility. Designed scaffolds comprising natural and synthetic materials are now widely used in the reconstruction of damaged tissues especially neural tissues. Polyhydroxyalkanoate scaffolds with properties similar to neural structures can be more effective in the reconstruction process. Better cell adhesion and migration, more guiding of axons, and structural features, such as porosity, provide a clearer role in the restoration of neural tissues. Here application of polyhydroxyalkonates as the potential biomaterials in improving performance of injured nerves and neural reconstruction is reviewed. [ABSTRACT FROM AUTHOR]

Environments contaminated with mixtures of chlorinated hydrocarbons represent a formidable challenge for bioremediation because biodegradation of all components of the mixture must be demonstrated. In this study a soil site contaminated with hexachloro-1,3-butadiene (HCBD), hexachlorobenzene (HCB), and perchloroethene (PCE) was investigated. Environmental parameters (including toxicity) and microbial community composition were characterized. The lack of scientific literature on HCBD biodegradation led to attempts to develop HCBD-respiring enrichment cultures and to test the hypothesis that known PCE-degrading cultures could dechlorinate HCBD. No HCBD dechlorination was observed. An alternative approach, using electron shuttles to degrade the mixture of chlorinated hydrocarbons, was compared with the activity of zero-valent iron. The authors conclude that electron shuttles offer promise for the in situ treatment of mixtures of chlorinated hydrocarbons. [ABSTRACT FROM AUTHOR]

A field and laboratory investigation of natural attenuation, focusing on anaerobic biodegradation, was conducted in a forested wetland where a plume of trichloroethene discharges from a sand aquifer through organic-rich wetland and stream-bottom sediments. The rapid response of the wetland hydrology to precipitation events altered groundwater flow and geochemistry during wet conditions in the spring compared to the drier conditions in the summer and fall. During dry conditions, partial reductive dechlorination of trichloroethene to cis-1,2-dichloroethene occurred in methanogenic wetland porewater. Influx of oxygenated recharge during wet conditions resulted in a change from methanogenic to iron-reducing conditions and a lack of 1,2-dichloroethene production in the wet spring conditions. During these wet conditions, dilution was the primary attenuation mechanism evident for trichloroethene in the wetland porewater. Trichloroethene degradation was insignificant in anaerobic microcosms constructed with the shallow wetland sediment, and microbiological analyses showed a low microbial biomass and absence of known dehalorespiring microorganisms. Despite the typically organic-rich characteristic of wetland sediments, natural attenuation by anaerobic degradation may not be an effective groundwater remediation for chlorinated solvents at all sites. [ABSTRACT FROM AUTHOR]

All chemical compounds may undergo a variety of processes resulting from chemical, biological, or photochemical reactions. Depending on the environmental compartment in which organic compounds are present (e.g., soil, benthic sediments, surfacewaters, and groundwaters), they can undergo slow changes resulting from different chemical, physical, biological, or photochemical processes. In this study, different degradation pathways for selected persistent organic pollutants under varying conditions are presented. The problem of intermediate products that form during the degradation of substances, the toxicity of substances that are the products of organic compounds degradation, and the ways to identify such substances have been discussed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]