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[en] This project began with the simple goal of trying to understand the diversity of dissimilatory metal-reducing microorganisms that might be found in subsurface environments. It ended with a sophisticated understanding not only of what microorganisms are important for metal reduction in uranium-contaminated subsurface environments, but also their physiological status during in situ uranium bioremediation. These findings have provided unprecedented insight into uranium bioremediation and the methods by which this process might be optimized. A brief summary of the major accomplishments of the project is given.
[en] Full tex:Soil animals are the most suitable biological indicators of radioactive pollution because they are parts of nutritional chains and webs, occur in relatively high numbers and can be collected during most parts of the year.The use of earthworms in the soils from Ramana iodine plant area of Absheron peninsula, which is rich with radionuclide and in the soil mixed with RaCl2 and UO2SO4 salt solutions in different concentrations, for resistance to ionizing radiation in soil is reviewed.Effect of radionuclides on vital functions of earthworms and determination of radionuclides (before and after experiments) in contaminated soils by ?-spectrometer were carried out in laboratory condition during a month. Regarding to ?-spectrometric results there were determined that earthworms had absorbed most of radioactive elements and allocated them as coprogenous substances on the upper layer of soil. In Ramana soils mostly the 238U radionuclides were highly accumulated in gut cells of the earthworms. By the influence of radioactive elements it was shown that the earthworms from Ramana iodine plant territory variants had proved particularly sensitive to an increased Ra-radiation background and to iodine factor.It was interestingly established the proportional dependence between rising level of accumulation in earthworms' body and in their coprolites and increasing of radioactive salts containing in the soils treated by UO2SO4 and RaCl2 solutions.Thus there is different level of radioresistance for earthworms and they are among the best bioindicators of polluted soils. There was an obvious perspective of using of earthworms as bioremediators in polluted soil with radionuclides in future as well.
[en] Radio-resistant strains isolated from mining sites in Khouribgua, have been identified following a morphological, biochemical and molecular level. The scope of the study is biodegradability of the two pesticides namely methyl parathion and methomyl through these identified strains .The objective of this research is to improve the biodegradability potential of pesticides by identified strains via ionizing radiation Gamma known for its mutagenic potential.
[en] Plutonium contamination in the environment is generally low-level and may be present and transported in a range of forms (IV, V, VI). Current remediation strategies are costly, financially and in terms of increased exposure risk to people and the environment. In situ bacterial biostabilization is a promising alternative
[en] Microorganisms are ubiquitous in subsurface environments although their populations sizes and metabolic activities can vary considerably depending on energy and nutrient inputs. As a result of their metabolic activities and the chemical properties of their cell surfaces and the exopolymers they produce, microorganisms can directly or indirectly facilitate the biotransformation of radionuclides, thus altering their solubility and overall fate and transport in the environment. Although biosorption to cell surfaces and exopolymers can be an important factor modifying the solubility of some radionuclides under specific conditions, oxidation state is often considered the single most important factor controlling their speciation and, therefore, environmental behavior.
[en] This report summarizes progress made from June 2003 to July 2004. During this period research focused on further understanding the factors controlling the growth and activity of dissimilatory metal reducers in subsurface environments and the application of these findings to better design of strategies for in situ bioremediation of uranium
[en] The bioremediation of nickel pollution of the mixed metal solution containing lead, nickel and chromium has been studied by using the natural biomass of Oedogonium sp. The effect of various concentrations of the biomass show that the maximum biosorption of Nickel from the mixed metal solution occurred at 3.5g, when the concentration of Nickel pollutant was 50 ppm in a 100 ml of the mixed metal solution. The biosorption of Nickel from single metal solution show that biosorption of lead and chromium do not interfere with the biosorption of Nickel by Oedogonium sp. (author)
[en] Highlights: • This is the first structure of 1,2-HQD from Gram-negative bacterium P. putida DLL-E4. • The Fe(III) is pentacoordinated by a typical His2Tyr2, the citrate anion and one water molecule. • Asp80, Thr81 and Val248 are responsible for the substrate specificity of PnpC. • The N-terminal α-helix of PnpC is necessary for its soluble expression and enzyme catalysis. Hydroxyquinol 1,2-dioxygenase is a key enzyme in the hydroxyquinol pathway of p-nitrophenol (PNP) degradation, and catalyzes the ring cleavage of benzenetriol to maleylacetate. Here, we report the first structure of a hydroxyquinol 1,2-dioxygenase from the Gram-negative bacterium Pseudomonas putida DLL-E4 (PnpC) at the resolution of 2.1 Å. The tertiary structure of PnpC resembles that of the homologous intradiol dioxygenases. The catalytic Fe(III) is pentacoordinated by the conserved Tyr160, Tyr194, His218 and His220, the citrate anion and one water molecule. Among the residues expected to interact with the substrate, structural comparison with the (chloro)catechol dioxygenases suggested that Asp80, Thr81 and Val248 are responsible for the substrate specificity. Moreover, truncation of the N-terminal α-helix of PnpC suggested the N-terminal domain is required for its soluble expression and enzyme catalysis. Our results might provide insights in the substrate recognition and rational design of this enzyme class to be used in bioremediation.