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Toxicological stress in aquatic organisms is caused by the discharge of hundreds of toxic pollutants and contaminants among which the current study concentrates on the toxic effect of non-steroidal anti-inflammatory drug ibuprofen (IBF) and the trace element selenium (Se). In this study, IBF and Se toxicity on freshwater mussel Lamellidens marginalis was studied for 14 days, and in silico predictions for their degradation were made using Molecular modelling and Quantum Mechanical approaches. The degrading propensity of cytochrome c oxidase proteins from Trametes verticillatus and Thauera selenatis (Turkey tail fungi and Gram-negative bacteria) is examined into atom level. The results of molecular modelling study indicate that ionic interactions occur in the T. selenatis -HEME bound complex by Se interacting directly with HEME, and in the T. versicolor -HEME bound complex by IBF bound to a nearby region of HEME. Experimental and theoretical findings suggest that, the toxicological effects of Se and IBF pollution can be reduced by bioremediation with special emphasis on T. versicolor , and T. selenatis , which can effectively interact with Se and IBF present in the environment and degrade them. Besides, this is the first time in freshwater mussel L. marginalis that ibuprofen and selenium toxicity have been studied utilizing both experimental and computational methodologies for their bioremediation study. [Display omitted] • Mussels increased their metabolism with increasing concentration gradient (IBF + Se). • Cellular damage and decreased redox balance in all exposure conditions. • Predictions for degradation by Molecular modelling and Quantum Mechanics. • Genotoxicity and histological damage were found regardless the treatment. [ABSTRACT FROM AUTHOR]

Anaerobic degradation of alkylbenzenes with side chains longer than that of toluene was studied in freshwater mud samples in the presence of nitrate. Two new denitrifying strains, EbN1 and PbN1, were isolated on ethylbenzene and n-propylbenzene, respectively. For comparison, two further denitrifying strains, ToN1 and mXyN1, were isolated from the same mud with toluene and m-xylene, respectively. Sequencing of 16SrDNA revealed a close relationship of the new isolates to Thauera selenatis. The strains exhibited different specific capacities for degradation of alkylbenzenes. In addition to ethylbenzene, strain EbN1 utilized toluence, but not propylbenzene. In contrast, propylbenzene-degrading strain PbN1 did not grow on toluene, but was able to utilize ethylbenzene. Strain ToN1 used toluene as the only hydrocarbon substrate, whereas strain mXyN1 utilized both toluene and m-xylene. Measurement of the degradation balance demonstrated complete oxidation of ethylbenzene to CO by strain EbN1. Further characteristic substrates of strains EbN1 and PbN1 were 1-phenylethanol and acetophenone. In contrast to the other isolates, strain mXyN1 did not grow on benzyl alcohol. Benzyl alcohol (also m-methylbenzyl alcohol) was even a specific inhibitor of toluene and m-xylene utilization by strain mXyN1. None of the strains was able to grow on any of the alkylbenzenes with oxygen as electron acceptor. However, polar aromatic compounds such as benzoate were utilized under both oxic and anoxic conditions. All four isolates grew anaerobically on crude oil. Gas chromatographic analysis of crude oil after growth of strain ToN1 revealed specific depletion of toluene. [ABSTRACT FROM AUTHOR]