Tetrathionate production by sulfur-oxidizing bacteria and the role of tetrathionate in the sulfur cycle in sediments of the Baltic Sea

The role of tetrathionate in the sulfur cycle of Baltic Sea sediments was investigated in different habitats and under a variety of environmental conditions. Sediment profiles were recorded with regard to numbers of thiosulfate oxidizing bacteria, concentrations of sulfur compounds, and potential rates of thiosulfate oxidation. Products of thiosulfate oxidation were quantified in incubated sediment samples and in pure cultures. Evidence was found that tetrathionate is formed within these sediments, that sulfur oxidizing bacteria are present in considerable numbers, that these bacteria are of major importance in the oxidation of reduced sulfur compounds in their habitat, and that tetrathionate is an important oxidation product of these bacteria. Thiosulfate is oxidized by bacteria isolated from these sediments to varying proportions of tetrathionate, sulfate, and also elemental sulfur. In highly sulfidic sediments and in the presence of large amounts of organic matter, tetrathionate was present in sediment horizons in which thiosulfate and elemental sulfur also accumulated. A tetrathionate cycle is proposed to be active in natural marine and brackish water sediments in which, due to combined bacterial action and chemical reactions, a net oxidation of sulfide to elemental sulfur occurs in the presence of catalytic amounts of thiosulfate and tetrathionate

Correlation of viable cell counts, metabolic activity of sulphur-oxidizing bacteria and chemical parameters of marine sediments

Viable counts of aerobic and anaerobic chemotrophic sulphur-oxidizers as well as phototrophic sulphur bacteria were determined in sediment samples taken from two different areas along the Baltic Sea shore which were known to regularly develop sulphidic conditions. Depth profiles of bacterial cell counts were correlated with concentration profiles of chloride, sulphate, sulphide, nitrate and phosphate in the pore water of these sediments and with potential activities of nitrate reduction, thiosulphate transformation and sulphate formation. The data revealed a complex multilayered structure within the sediments. Sulphide was released into the water from sediments of both sampling areas, but it was found that light and the availability of oxygen significantly reduced this amount. In the highly reduced sediment at Hiddensee, the highest numbers of phototrophic and chemotrophic sulphur-oxidizers were found near the sediment surface. Therefore, it was concluded that the combined action of both groups of bacteria most efficiently oxidizes reduced sulphur compounds in the top layers of the sediments. Nitrate may replace oxygen as final electron acceptor and will support oxidation of sulphide, in particular when oxygen and light are limitin

Insights on the mixtures of imidazolium based ionic liquids with molecular solvents

The properties of ionic liquid (1-ethyl-3-methylimidazolium BF4 and 1-butyl-3-methylimidazolium BF4) + solvents (water, ethylene glycol or dimethylformamide) mixtures are studied in the full composition range as a function of mixture composition and temperature. These mixed fluids are characterized by selected physical properties and microscopic studies using density functional theory and molecular dynamics simulations. The reported results showed large non-ideal mixtures, which are caused by strong anion (BF4) – molecular solvent hydrogen bonding. Likewise, the interaction of ions, evolves from anion-cation pairs solvated by molecular solvents, for mixtures rich in molecular solvent, to large ionic aggregates for ionic liquid rich mixtures separated by a transitional composition regime. The large non-linearity of the evolution of microscopic properties with mixture composition is the origin of macroscopic thermodynamic deviations from ideality.Junta de Castilla y León (Spain, project BU324U14

Diversity of thiosulfate-oxidizing bacteria from marine sediments and hydrothermal vents

Author Posting. © American Society for Microbiology, 2000. This article is posted here by permission of American Society for Microbiology for personal use, not for redistribution. The definitive version was published in Applied and Environmental Microbiology 66 (2000): 3125-3133, doi:10.1128/AEM.66.8.3125-3133.2000.Species diversity, phylogenetic affiliations, and environmental occurrence patterns of thiosulfate-oxidizing marine bacteria were investigated by using new isolates from serially diluted continental slope and deep-sea abyssal plain sediments collected off the coast of New England and strains cultured previously from Galapagos hydrothermal vent samples. The most frequently obtained new isolates, mostly from 103- and 104-fold dilutions of the continental slope sediment, oxidized thiosulfate to sulfate and fell into a distinct phylogenetic cluster of marine alpha-Proteobacteria. Phylogenetically and physiologically, these sediment strains resembled the sulfate-producing thiosulfate oxidizers from the Galapagos hydrothermal vents while showing habitat-related differences in growth temperature, rate and extent of thiosulfate utilization, and carbon substrate patterns. The abyssal deep-sea sediments yielded predominantly base-producing thiosulfate-oxidizing isolates related to Antarctic marine Psychroflexus species and other cold-water marine strains of the Cytophaga-Flavobacterium-Bacteroides phylum, in addition to gamma-proteobacterial isolates of the genera Pseudoalteromonas and Halomonas-Deleya. Bacterial thiosulfate oxidation is found in a wide phylogenetic spectrum of Flavobacteria and Proteobacteria.Andreas Teske was supported by DFG postdoctoral fellowship 262-1/1 and a subsequent WHOI postdoctoral fellowship

Contextualization and completion of Vilém Zdeněk Stezka’s Wind serenade

textVilém Zdeněk Stezka's final work, Wind Serenade from 1939, was partially lost in a small earthquake that occurred in Bergamo, Italy on July 31, 2012. In this study I present both analysis and contextualization of the surviving fragments of Stezka's music. Some fragments consist of completed movements, others survive only in short score format, and still others have been completely destroyed. I have used the knowledge gained therefrom to complete Wind Serenade in a fashion that is appropriate in both style and expression. I have also detailed the process of completion in this study as each fragment demands both a unique perspective and technique.Musi

Doctoral thesis recital (composition)

textAnnachronism 1 -- Procession/Precession -- Tres canciones -- Rondo a Calvino -- Capriccio cavato -- Songs for the sane.MusicSupervisor not listed on recital program

Diffusionsinduzierte Brechungsindexaenderungen in Polymerfilmen als Funktionsprinzip optischer Chemosensoren

In this thesis several polymer materials have been investigated with respect to their application as optical chemo-sensors, which are based on molecule diffusion into thin sensitive layers. The dynamic response of such sensors is mainly controlled by the diffusion kinetics of the molecules in the film. The solution of the diffusion differential equation (2nd Fick's law) in the case of thin films yields the temporary concentration profile of the molecules in the film. Linearity between the refractive index changes and the concentration follows directly from the Lorentz-Lorenz equation and therefore gives the same variation for the index changes. With that the development of the refractive index profile during in- and out-diffusion is well described by the diffusion theory and consequently the dynamic response of the optical sensor can be modelled by a suitable theory. Thin glass/silver/polymer multilayer systems have been characterised with respect to their optical sensing parameters by using metal film enhanced leaky mode spectroscopy. This useful optical technique, which offers the observation of the surface plasmon resonance and the leaky modes of thin dielectric films, has been improved for the analysis of inhomogeneous refractive index profiles by using a transfer-matrix formalism for layered media. Furthermore, waveguide birefringence experiments on thin anisotropic polyimide films as planar lightguides have been carried out to show how the sensitivity of the sensor can be optimised by a suitable choice or a specific modification of the polymer material.SIGLEAvailable from: http://www.iwi-iuk.org/dienste/TheO/ / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman