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Reduced Sulfur Compounds (reduced + sulfur_compound)
Selected AbstractsDie vielen Seiten des Sulfids.BIOLOGIE IN UNSERER ZEIT (BIUZ), Issue 5 2009Tödlich und doch lebensnotwendig Abstract Schwefelwasserstoff ist äußerst giftig und hat dennoch zahlreiche physiologische Funktionen. Tiere aus sulfidhaltigen Lebensräumen können sich effektiv vor einer Sulfidvergiftung schützen und nutzen diese reduzierte Schwefelverbindung sogar als Energielieferant. Das reichhaltige Leben an den Hydrothermalquellen der Tiefsee basiert vollständig auf der Oxidation anorganischer Substanzen, wobei Sulfid eines der Hauptsubstrate ist. Für den Menschen spielt Sulfid als gasförmiges Signalmolekül eine wichtige Rolle. Es wird in vielen Geweben produziert und ist an einigen entscheidenden Stoffwechselvorgängen, wie beispielsweise der Regulation des Blutdrucks und der Insulinsekretion beteiligt. Störungen des Schwefelstoffwechsels führen zu verschiedenen Erkrankungen, so dass die genaue Kenntnis der Umsetzung und Wirkungsweisen von Sulfid medizinisch von großem Interesse ist. Hydrogen sulfide is highly toxic, but nevertheless it has several physiological functions. Animals from sulfide containing habitats are able to protect themselves from sulfide poisoning and furthermore use this reduced sulfur compound for ATP production. Life at the deep-sea hydrothermal vents entirely depends on the oxidation of inorganic substrates, mainly sulfide. In humans sulfide acts as a gaseous signalling molecule. It is produced in many tissues and takes part in a number of important metabolic processes such as the regulation of blood pressure and insulin secretion. Several severe diseases are caused by dysfunctions in sulfur metabolism. Thus, a detailed knowledge of the reactions and effects of hydrogen sulfide is of considerable clinical relevance. [source] Multiple bacterial symbionts in two species of co-occurring gutless oligochaete worms from Mediterranean sea grass sedimentsENVIRONMENTAL MICROBIOLOGY, Issue 12 2008Caroline Ruehland Summary Gutless oligochaete worms are found worldwide in the pore waters of marine sediments and live in symbiosis with chemoautotrophic sulfur-oxidizing bacteria. In the Mediterranean, two species of gutless oligochaete worms, Olavius algarvensis and O. ilvae, co-occur in sediments around sea grass beds. These sediments have extremely low sulfide concentrations (< 1 ,M), raising the question if O. ilvae, as shown previously for O. algarvensis, also harbours sulfate-reducing symbionts that provide its sulfur-oxidizing symbionts with reduced sulfur compounds. In this study, we used fluorescence in situ hybridization (FISH) and comparative sequence analysis of genes for 16S rRNA, sulfur metabolism (aprA and dsrAB), and autotrophic carbon fixation (cbbL) to examine the microbial community of O. ilvae and re-examine the O. algarvensis symbiosis. In addition to the four previously described symbionts of O. algarvensis, in this study a fifth symbiont belonging to the Spirochaetes was found in these hosts. The symbiotic community of O. ilvae was similar to that of O. algarvensis and also included two gammaproteobacterial sulfur oxidizers and two deltaproteobacterial sulfate reducers, but not a spirochete. The phylogenetic and metabolic similarity of the symbiotic communities in these two co-occurring host species that are not closely related to each other indicates that syntrophic sulfur cycling provides a strong selective advantage to these worms in their sulfide-poor environment. [source] Performance of a full-scale biotrickling filter treating H2S at a gas contact time of 1.6 to 2.2 secondsENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 2 2003David Gabriel Emission of objectionable odors is a major problem for wastewater treatment and other processing facilities. Biological treatment is a promising alternative to conventional control methods, such as chemical scrubbing, but historically, biotreatment has always required significantly larger reactor volumes than chemical scrubbers. In this paper, we present several aspects of the operation and performance of a chemical scrubber, retrofitted to operate as a biotrickling filter treating 16,000 m3 h,1 of foul air with the original gas contact time of 1.6 to 2.2 seconds. In continuous operation for more than a year, the biotrickling filter has shown stable performance and robust behavior for H2S treatment, with pollutant removal performance comparable to using a chemical scrubber. Reclaimed water was used as a nutrient source for the process, and to maintain the pH in the biotrickling filter between 1.5 and 2.2. At a gas contact time of 1.6 seconds, H2S removal was in excess of 95% for sustained inlet H2S concentrations as high as 30 ppmv. This corresponds to volumetric elimination rates of 95 to 105 g H2S m,3 h,1. Efficiencies of about 90% were observed under transient conditions at 2.2 seconds gas contact time for inlet concentration peaks up to 60 ppmv. The biotrickling filter also removed significant amounts of reduced sulfur compounds, ammonia, and volatile organic compounds present in traces in the air, which is important in practical applications. Selected experiments, such as intermittent trickling operation and a one-month operation period at neutral pH, are also presented. Results indicate that the intermittent trickling operation does not have a significant effect on H2S removal. However, when operated at neutral pH, biotrickling filter performance clearly decreased, probably due to an excessive chlorine supply to the reactor through the make-up water. The study demonstrates that biotrickling filters can replace chemical scrubbers as a safer, more economical technique for odor control. [source] Biochemistry and molecular biology of lithotrophic sulfur oxidation by taxonomically and ecologically diverse bacteria and archaeaFEMS MICROBIOLOGY REVIEWS, Issue 6 2009Wriddhiman Ghosh Abstract Lithotrophic sulfur oxidation is an ancient metabolic process. Ecologically and taxonomically diverged prokaryotes have differential abilities to utilize different reduced sulfur compounds as lithotrophic substrates. Different phototrophic or chemotrophic species use different enzymes, pathways and mechanisms of electron transport and energy conservation for the oxidation of any given substrate. While the mechanisms of sulfur oxidation in obligately chemolithotrophic bacteria, predominantly belonging to Beta - (e.g. Thiobacillus) and Gammaproteobacteria (e.g. Thiomicrospira), are not well established, the Sox system is the central pathway in the facultative bacteria from Alphaproteobacteria (e.g. Paracoccus). Interestingly, photolithotrophs such as Rhodovulum belonging to Alphaproteobacteria also use the Sox system, whereas those from Chromatiaceae and Chlorobi use a truncated Sox complex alongside reverse-acting sulfate-reducing systems. Certain chemotrophic magnetotactic Alphaproteobacteria allegedly utilize such a combined mechanism. Sulfur-chemolithotrophic metabolism in Archaea, largely restricted to Sulfolobales, is distinct from those in Bacteria. Phylogenetic and biomolecular fossil data suggest that the ubiquity of sox genes could be due to horizontal transfer, and coupled sulfate reduction/sulfide oxidation pathways, originating in planktonic ancestors of Chromatiaceae or Chlorobi, could be ancestral to all sulfur-lithotrophic processes. However, the possibility that chemolithotrophy, originating in deep sea, is the actual ancestral form of sulfur oxidation cannot be ruled out. [source] | ||||||||||