Geoglobus acetivorans sp. nov., an iron(III)-reducing archaeon from a deep-sea hydrothermal vent

En libre-accès sur Archimer : http://archimer.ifremer.fr/doc/2009/publication-6977.pdfInternational audienceA hyperthermophilic, anaerobic, dissimilatory Fe(III)-reducing, facultatively chemolithoautotrophic archaeon (strain SBH6(T)) was isolated from a hydrothermal sample collected from the deepest of the known World Ocean hydrothermal fields, Ashadze field (1 degrees 58' 21'' N 4 degrees 51' 47'' W) on the Mid-Atlantic Ridge, at a depth of 4100 m. The strain was enriched using acetate as the electron donor and Fe(III) oxide as the electron acceptor. Cells of strain SBH6(T) were irregular cocci, 0.3-0.5 mum in diameter. The temperature range for growth was 50-85 degrees C, with an optimum at 81 degrees C. The pH range for growth was 5.0-7.5, with an optimum at pH 6.8. Growth of SBH6(T) was observed at NaCl concentrations ranging from 1 to 6 % (w/v) with an optimum at 2.5 % (w/v). The isolate utilized acetate, formate, pyruvate, fumarate, malate, propionate, butyrate, succinate, glycerol, stearate, palmitate, peptone and yeast extract as electron donors for Fe(III) reduction. It was also capable of growth with H(2) as the sole electron donor, CO(2) as a carbon source and Fe(III) as an electron acceptor without the need for organic substances. Fe(III) [in the form of poorly crystalline Fe(III) oxide or Fe(III) citrate] was the only electron acceptor that supported growth. 16S rRNA gene sequence analysis revealed that the closest relative of the isolated organism was Geoglobus ahangari 234(T) (97.0 %). On the basis of its physiological properties and phylogenetic analyses, the isolate is considered to represent a novel species, for which the name Geoglobus acetivorans sp. nov. is proposed. The type strain is SBH6(T) (=DSM 21716(T) =VKM B-2522(T))

Deferribacter autotrophicus sp. nov., an iron(III)-reducing bacterium from a deep-sea hydrothermal vent

En libre-accès sur Archimer : http://archimer.ifremer.fr/doc/2009/publication-6598.pdfInternational audienceA thermophilic, anaerobic, chemolithoautotrophic bacterium (designated strain SL50(T)) was isolated from a hydrothermal sample collected at the Mid-Atlantic Ridge from the deepest of the known World ocean hydrothermal fields, Ashadze field (1 degrees 58' 21'' N 4 degrees 51' 47'' W) at a depth of 4100 m. Cells of strain SL50(T) were motile, straight to bent rods with one polar flagellum, 0.5-0.6 mum in width and 3.0-3.5 mum in length. The temperature range for growth was 25-75 degrees C, with an optimum at 60 degrees C. The pH range for growth was 5.0-7.5, with an optimum at pH 6.5. Growth of strain SL50(T) was observed at NaCl concentrations ranging from 1.0 to 6.0 % (w/v) with an optimum at 2.5 % (w/v). The generation time under optimal growth conditions for strain SL50(T) was 60 min. Strain SL50(T) used molecular hydrogen, acetate, lactate, succinate, pyruvate and complex proteinaceous compounds as electron donors, and Fe(III), Mn(IV), nitrate or elemental sulfur as electron acceptors. The G+C content of the DNA of strain SL50(T) was 28.7 mol%. 16S rRNA gene sequence analysis revealed that the closest relative of strain SL50(T) was Deferribacter abyssi JR(T) (95.5 % similarity). On the basis of its physiological properties and phylogenetic analyses, the isolate is considered to represent a novel species, for which the name Deferribacter autotrophicus sp. nov. is proposed. The type strain is SL50(T) (=DSM 21529(T)=VKPM B-10097(T)). Deferribacter autotrophicus sp. nov. is the first described deep-sea bacterium capable of chemolithoautotrophic growth using molecular hydrogen as an electron donor and ferric iron as electron acceptor and CO(2) as the carbon source

Corpora in Text-Based Russian Studies

This chapter focuses on textual data that are collected for a specific purpose, which are usually referred to as corpora. Scholars use corpora when they examine existing instances of a certain phenomenon or to conduct systematic quantitative analyses of occurrences, which in turn reflect habits, attitudes, opinions, or trends. For these contexts, it is extremely useful to combine different approaches. For example, a linguist might analyze the frequency of a certain buzzword, whereas a scholar in the political, cultural, or sociological sciences might attempt to explain the change in language usage from the data in question.Peer reviewe

Dissimilatory reduction of Fe(III) by thermophilic bacteria and archaea in deep subsurface petroleum reservoirs of Western Siberia

Twenty-five samples of stratal fluids obtained from a high-temperature (60-84 degrees C) deep subsurface (1700-2500 m) petroleum reservoir of Western Siberia were investigated for the presence of dissimilatory Fe(III)-reducing microorganisms. Of the samples, 44% and 76% were positive for Fe(III) reduction with peptone and Hz respectively as electron donors. In most of these samples, the numbers of culturable thermophilic Hz-utilizing iron reducers were in the order of 10-100 cells/ml. Nine strains of thermophilic anaerobic bacteria and archaea isolated from petroleum reservoirs were tested for their ability to reduce Fe(III). Eight strains belonging to the genera Thermoanaerobacter, Thermotoga, and Thermococcus were found capable of dissimilatory Fe(m) reduction, with peptone or H-2 as electron donor and amorphous Fe(III) oxide as electron acceptor. These results demonstrated that Fe(m) reduction may be a common feature shared by a wide range of anaerobic thermophiles and hyperthermophiles in deep subsurface petroleum reservoirs

Thermosipho geolei sp nov., a thermophilic bacterium isolated from a continental petroleum reservoir in Western Siberia

The novel isolate reduced elemental sulfur ana cystine. but not thiosulfate sulfate, to hydrogen sulfide, The G+C content of the genomic DNA was 30.0 mol%, As determined by 16S rDNA sequence analysis, this organism Three strictly anaerobic, thermophilic bacteria (SL31(T), SL30 and MLM39636) were isolated from a deep continental oil reservoir in Western Siberia (Russia), Following the mid-exponential phase of growth, the non-motile rod-shaped organisms were surrounded by a sheath-like structure, As DNA-DNA hybridizations showed that these strains were highly related genomically, only strain SL31T was studied in detail, The temperature range for growth of strain SL31T was between 45 and 75 degreesC, with optimum growth at 70 degreesC, its optimum ph and NaCl concentration for growth were pH 7.5 and 20-30 g l(-1), respectively. The novel isolate reduced elemental sulfur and cystine, but not thiosulfate or belonged to the genus Thermosipho. DNA-DNA hybridization levels between strain SL31T and type strains of the previously described species of Thermosipho were less than 10%, On the basis of physiological and molecular properties, it is proposed that this organism should be placed in a new species, Thermosipho geolei sp, nov, The novel organism represents the first species of the genus Thermosipho that has been isolated from a petroleum reservoir, The type strain is SL31(T) (= DSM 13256(T) = JCM 10986(T))

Reduction of uranium(VI) phosphate during growth of the thermophilic bacterium thermoterrabacterium ferrireducens

The thermophilic, gram-positive bacterium Thermoterrabacterium ferrireducens coupled organotrophic growth to the reduction of sparingly soluble U(VI) phosphate. X-ray powder diffraction and X-ray absorption spectroscopy analysis identified the electron acceptor in a defined medium as U(VI) phosphate [uramphite; (NH4)(UO2)(PO4) · 3H 2O], while the U(IV)-containing precipitate formed during bacterial growth was identified as ningyoite [CaU(PO4)2 · H2O]. This is the first report of microbial reduction of a largely insoluble U(VI) compound

Thermosinus carboxydivorans gen. nov., sp. nov., a new anaerobic, thermophilic, carbon-monoxide-oxidizing, hydrogenogenic bacterium from a hot pool of Yellowstone National Park

A new anaerobic, thermophilic, facultatively carboxydotrophic bacterium, strain Nor1T, was isolated from a hot spring at Norris Basin, Yellowstone National Park. Cells of strain Nor1T were curved motile rods with a length of 2.6-3 μm, a width of about 0.5 μm and lateral flagellation. The cell wall structure was of the Gram-negative type. Strain Nor1T was thermophilic (temperature range for growth was 40-68 °C, with an optimum at 60 °C) and neutrophilic (pH range for growth was 6.5-7.6, with an optimum at 6.8-7.0). It grew chemolithotrophically on CO (generation time, 1.15 h), producing equimolar quantities of H2 and CO2 according to the equation CO+H2O → CO2 + H2. During growth on CO in the presence of ferric citrate or amorphous ferric iron oxide, strain Nor1T reduced ferric iron but produced H2 and CO2 at a ratio close to 1:1, and growth stimulation was slight. Growth on CO in the presence of sodium selenite was accompanied by precipitation of elemental selenium. Elemental sulfur, thiosulfate, sulfate and nitrate did not stimulate growth of strain Nor1T on CO and none of these chemicals was reduced. Strain Nor1T was able to grow on glucose, sucrose, lactose, arabinose, maltose, fructose, xylose and pyruvate, but not on cellobiose, galactose, peptone, yeast extract, lactate, acetate, formate, ethanol, methanol or sodium citrate. During glucose fermentation, acetate, H2 and CO2 were produced. Thiosulfate was found to enhance the growth rate and cell yield of strain Nor1T when it was grown on glucose, sucrose or lactose; in this case, acetate, H2S and CO2 were produced. In the presence of thiosulfate or ferric iron, strain Nor1T was also able to grow on yeast extract. Lactate, acetate, formate and H2 were not utilized either in the absence or in the presence of ferric iron, thiosulfate, sulfate, sulfite, elemental sulfur or nitrate. Growth was completely inhibited by penicillin, ampicillin, streptomycin, kanamycin and neomycin. The DNA G+C content of the strain was 51.7 ± 1 mol%. Analysis of the 16S rRNA gene sequence revealed that strain Nor1T belongs to the Bacillus-Clostridium phylum of the Gram-positive bacteria. On the basis of the studied phenotypic and phylogenetic features, we propose that strain Nor1T be assigned to a new genus, Thermosinus gen. nov. The type species is Thermosinus carboxydivorans sp. nov. (type strain, Nor1T = DSM 14886T = VKM B-2281T).This work was supported by the NATO LST.CLG. 978269 grant, the CRDF RB2-2379- MO-02 grant and the Program ‘Molecular and Cell Biology’ of the Russian Academy of Sciences. J. M. G. acknowledges support from the Spanish Ministry of Science and Technology through a Ramón y Cajal contract and grant REN2002-00041.Peer Reviewe