The haloalkane dehalogenase of soil bacteria Xanthobacter autotrophicus is an enzyme, which catalyzes the environmentally important detoxification process, namelythe hydrolytic cleavage of the carbon−halogen bond. A molecular modeling study has been conducted with the structures of the wild-type enzyme and its mutants in order to investigate the mechanisms of the dehalogenation reaction at molecular level. Semiempirical quantum chemical calculations have been applied to elucidate the importance of the active site residues for kinetic and thermodynamic characteristics in the first step of dehalogenation reaction. The results obtained from these calculations have been compared with previously published experimental results. The strength of the application of molecular modeling method for the study of the evolutionary aspects of biodegradation of organic pollutants is discussed.

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In this work biological effects of two common kinds of green tea (Chinese Gunpowder and Japanese Sencha) were analyzed using three independent tests of antimutagenicity: 1) the Ames test with Salmonella typhimurium TA98, 2) cytogenetic analysis of peripheral blood lymphocytes (CAPL), and 3) test with Saccharomyces cerevisiae D7. Tea extracts were allowed to be antimutagenic based on their ability to inhibit the mutagenic effect of standard mutagens. Amounts of (-)catechin and (-)catechin gallate in tea extracts were determined by high performance liquid chromatography on reversed phase (RP-HPLC). Antioxidant capacity was found using total radical-trapping antioxidant parameter (TRAP) method. Extracts from Gunpowder and Sencha exhibited high antimutagenic activity in the Ames test (24.7+/-3.7% and 34.1+/-2, 1% of inhibition without metabolic activation; 74.9+/-1.7% and 62.7+/-4.3% of inhibition with metabolic activation, respectively) as well as in S. cerevisiae D7 test (Gunpowder: 62.7+/-5.7% of Trp convertants inhibition and 52.6+/-5.3% of Ilv revertants inhibition; Sencha: 45.6+/-4.2% of Trp convertants inhibition, 50.0+/-4.8% of Ilv revertants inhibition). In the CAPL method reduced number of abberant cells as well as decreased number of chromosome breaks was observed using both green tea extracts. Antioxidant capacity and antimutagenicity of green tea extracts was higher than activity of tea catechins and flavonoids.

The sound absorption coefficient is a commonly used parameter to characterize the acoustic properties of materials. The fire performance of construction products has to be evaluated on the basis of their reaction to fire performance. The evaluation of the reaction to fire performance for the flammable construction materials which are in Class E reaction to fire is based on the ignitability test and the thermal test using the radiant heat source. For this study, nine types of STERED® products, which were made from the recycled automotive technical textiles, were chosen in order to evaluate their ability for sound absorption and the reaction to fire. The fire performance was evaluated on the basis of the relative mass loss in the radiant heat source test; the ignitability in accordance with ISO 11925-2, the possible appearance of flame, duration of flame, and the glowing during the single flame source test. The sound absorption of nine products was rated on the basis of the sound absorption coefficient and the noise reduction coefficient. The measurement was performed using the transfer function method in accordance with ISO 10534-2. From the nine tested types of STERED® products, the product Senizol AT XX2 TL 60 had the lowest mass loss at thermal loads up to 700 °C and it fulfilled the conditions for Class E reaction to fire. This product had the highest noise reduction coefficient of 0.81 and a high absorption coefficient for frequencies ranging between 500 Hz and 2000 Hz. The STERED® product Senizol AT XX2 TL 60, as well as Senizol AT 22 TL 50, Senizol AT 40 TL 25, Senizol AT XX4 TL 50 and Senizol AT XX4 TL 10 with a sound absorption coefficient α of between 0.80 to 0.95 and corresponding NRCs from 0.66 to 0.81, these STERED® products can be classified according to ISO 11654 into the sound absorption classes A and B.

Three bacterial isolates from soil, capable of degradation or transformation of nitroaromatic compounds and displaying a rod-coccus growth cycle, were studied by a polyphasic approach. On the basis of 16S rRNA sequence analysis and of chemotaxonomic characteristics, such as type A3a peptidoglycan with an interpeptide bridge Ala-Thr-Ala, the major menaquinone MK-9(H 2 ) and fatty acid composition, the isolates were assigned to the genus Arthrobacter. DNA-DNA hybridization, riboprinting and phenotypic studies revealed that the three strains constitute a single species, distinct from phylogenetically neighbouring Arthrobacter aurescens and Arthrobacter ilicis. A novel species, Arthrobacter nitroguajacolicus sp. nov., with the type strain G2-1 T (=CCM 4924 T =DSM 15232 T ) is proposed.