Browsing by Subject "Beggiatoa"
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Item Barite crusts from a brine pool in the Gulf of Mexico and the role of sulfur oxidizing bacteria in the precipitation of barite (BaSO4)(2013-10) Stevens, Eric W.Barite (BaSO4) is found in certain benthic marine settings, sometimes in proximity to microbial mat communities. However, barite precipitation is typically thought to form from a mixing of sulfate and barium rich fluids. Barite mineral crusts collected from a brine pool in the Gulf of Mexico contain filamentous mineral structures of grossly similar morphology to filamentous surrounding sulfur-oxidizing Beggiatoa mats. Molecular analyses of DNA preserved in the Gulf of Mexico barite crusts suggest that microbial sulfur-oxidation could play a role in the formation of these authigenic precipitates. Laboratory experiments using several strains of benthic marine bacteria show that sulfide-oxidizing bacteria have the capability to mediate barite precipitation via the oxidation of reduced sulfur compounds to sulfate. The results of this study suggest that sulfide-oxidizing bacteria may play a role in the precipitation of certain marine barite deposits, and expands the potential role of bacteria in marine barite formation to include their potential to generate sulfate under sulfate-limited conditions, such as some brine fluids.Item SERGEI WINOGRADSKY: A FOUNDER OF MODERN MICROBIOLOGY AND THE FIRST MICROBIAL ECOLOGIST(FEMS Microbiology Reviews, 2011-08-11) Dworkin, MartinSergei Winogradsky, was born in Russia in 1856 and was to become a founder of modern microbiology. After his Master’s degree work on the nutrition and growth physiology of the yeast Mycoderma vini at the University of St.Petersburg, he joined the laboratory of Anton DeBary in Strassburg. There he carried out his studies on the sulfur-oxidizing bacterium Beggiatoa which resulted in his formulation of the theory of chemolithotrophy. He then joined the Swiss Polytechnic Institute in Zurich where he did his monumental work on bacterial nitrification. He isolated the first pure cultures of the nitrifying bacteria and confirmed that they carried out the separate steps of the conversion of ammonia to nitrite and of nitrite to nitrate. This led directly to the concept of the cycles of sulfur and nitrogen in Nature. He returned to Russia and there was the first to isolate a free-living dinitrogen-fixing bacterium. In the flush of success, he retired from science and spent 15 years on his familial estate in the Ukraine. The Russian revolution forced him to flee Russia.He joined the Pasteur Institute in Paris where he spent his remaining 24 years initiating and developing the field of microbial ecology. He died in 1952.