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Fluoroaluminate molten salts are used in the Hall-Heroult industrial process for the production of aluminum by electrolysis. To better understand the mechanism of the dissolution of alumina (Al2O3) in cryolitic melts, we have studied the structure of these liquids up to 1025 °C by in-situ NMR of ²⁷Al, ²³Na, ¹⁹F, and ¹⁷O, using a laser-heated experimental setup. From these experiments we can propose a quantification of the different aluminum-bearing species AlF4^-, AlF5^2-, and AlF6^3- in the liquid and give a direct experimental evidence of the existence of at least two different oxy-fluoride species, Al2OF6^2- and Al2O2F4^2-, when dissolving alumina in the fluoride liquid. The obtained results are compared with other spectroscopic data obtained by in-situ Raman spectroscopy.

A mesophilic strain of sulfate-reducing bacterium, designated ALA-3T(T = type strain), was isolated from an anaerobic lagoon of a dairy wastewater treatment plant. The curved, Gram-negative, non-sporeforming cells (0.2 × 3.0-4.0 μm) existed singly or in chains, and were motile by single polar flagella. Optimum growth occurred at 35 °C and pH 7.5 on a medium containing lactate and sulfate. Thiosulfate or sulfite but not elemental sulfur, nitrate, or fumarate could also replace sulfate as an electron acceptor. Formate, alanine, aspartate, leucine, isoleucine, valine, and methionine, H2/CO2and ethanol also served as electron donors with sulfate as an electron acceptor. Pyruvate, casamino acids, peptone, serine, glycine, cysteine and threonine were fermented. Sulfite and thiosulfate were disproportionated to sulfate and sulfide. The G+C content of the DNA was 66 mol % G+C. Phylogenetic analysis revealed that Desulfovibrio africanuswas the nearest relative (similarity of 89%). Strain ALA-3Tis physiologically and phylogenetically different from other Desulfovibriospecies, and is designated Desulfovibrio aminophilussp. nov. (DSM 12254).

A strictly anaerobic, moderately halophilic, Gram‐negative, non‐motile rod‐shaped bacterium was isolated from an oil‐well head sample of an offshore Congolese oil field. The strain, designated SEBR 4224T(T=type strain), grew optimally at 42°C and pH 7.0 in a complex medium containing 10% NaCl with a generation time of 2.5 h. Strain SEBR 4224Tgrew on a range of carbohydrates including fructose, galactose, d‐glucose, maltose, d‐mannose, d‐ribose, sucrose, and trehalose. Yeast extract and/or bio‐Trypcase was required for growth on carbohydrates and could not be replaced with amino acids and/or vitamins. The end‐products from glucose fermentation were acetate, H2, and CO2. Thiosulfate and elemental sulfur were used as electron acceptors. Thiosulfate improved carbohydrate utilization and biomass yields. The G+C content of the isolate was 34 mol%. Ribosomal 16S rRNA sequence analysis showed that strain SEBR 4224Tis a new member of the genus Haloanaerobium. The lack of DNA homology with H. acetoethylicum, its closest relative, as determined by DNA‐DNA hybridization supports the designation of strain SEBR 4224Tas a new species, Haloanaerobium congolensesp. nov. The type strain is SEBR 4224T(=DSM 11287).

A disc‐shaped methanogenic bacterium designated strain SEBR 4847T(T=type strain) was isolated from a sample collected from an African offshore oil field. Strain SEBR 4847Twas non‐motile, had a G+C content of 50 mol% and produced methane from H2+CO2, formate, and CO2+propanol. Strain SEBR 4847Tgrew optimally at 37°C; no growth was observed at 25°C or 45°C. It grew in the presence of up to 50 g/l NaCl; 10–30 g/l was required for optimal growth. The optimum pH for growth was 7.0. Doubling time was about 10 h under optimal conditions. Based on 16S rRNA sequence analysis, the isolate was identified as a new species of the genus Methanoplanusand designated Methanoplanus petroleariussp. nov. The type strain is SEBR 4847T(=OCM 486).

A strictly anaerobic, moderately halophilic, Gram-negative, non-motile rod-shaped bacterium was isolated from an oil-well head sample of an offshore Congolese oil field. The strain, designated SEBR 4224T (T=type strain), grew optimally at 42°C and pH 7.0 in a complex medium containing 10% NaCl with a generation time of 2.5 h. Strain SEBR 4224T grew on a range of carbohydrates including fructose, galactose, d-glucose, maltose, d-mannose, d-ribose, sucrose, and trehalose. Yeast extract and/or bio-Trypcase was required for growth on carbohydrates and could not be replaced with amino acids and/or vitamins. The end-products from glucose fermentation were acetate, H2, and CO2. Thiosulfate and elemental sulfur were used as electron acceptors. Thiosulfate improved carbohydrate utilization and biomass yields. The G+C content of the isolate was 34 mol%. Ribosomal 16S rRNA sequence analysis showed that strain SEBR 4224T is a new member of the genus Haloanaerobium. The lack of DNA homology with H. acetoethylicum, its closest relative, as determined by DNA-DNA hybridization supports the designation of strain SEBR 4224T as a new species, Haloanaerobium congolense sp. nov. The type strain is SEBR 4224T (=DSM 11287).

A disc-shaped methanogenic bacterium designated strain SEBR 4847T (T=type strain) was isolated from a sample collected from an African offshore oil field. Strain SEBR 4847T was non-motile, had a G+C content of 50 mol% and produced methane from H2+CO2, formate, and CO2+propanol. Strain SEBR 4847T grew optimally at 37°C; no growth was observed at 25°C or 45°C. It grew in the presence of up to 50 g/l NaCl; 10–30 g/l was required for optimal growth. The optimum pH for growth was 7.0. Doubling time was about 10 h under optimal conditions. Based on 16S rRNA sequence analysis, the isolate was identified as a new species of the genus Methanoplanus and designated Methanoplanus petrolearius sp. nov. The type strain is SEBR 4847T (=OCM 486).

The 16S rRNA gene (rDNA) sequence analysis of four halophilic anaerobes: Halobacteroides halobius, H. lacunaris, Haloanaerobacter (Hb.) chitinovorans and H. acetoethylicus confirmed that they were all members of the family Haloanaerobiaceae. H. lacunaris and H. halobius were found to be more closely related to each other and were distantly related to Sporohalobacter lortetti and the members of the genera Haloanaerobium and Halothermothrix. These data are in agreement with their assignment to the genus Halobacteroides. Further analysis indicated that Hb. chitinovorans was closely affiliated to members of the genus Halobacteroides, and therefore we propose to transfer it to the genus Halobacteroides as H. chitinovorans comb. nov. This transfer would invalidate the genus Haloanaerobacter, as Hb. chitinovorans is the only member of this genus. The 16S rDNA sequence analysis of H. acetoethylicum indicated that it was very closely related to members of the genus Haloanaerobium, viz. Haloanaerobium (Ha.) praevalens, Ha. salsugo, and Ha. alcaliphilum, and hence we propose to transfer it to the genus Haloanaerobium as Ha. acetoethylicus comb. nov.

A thermophilic rod (strain SEBR 5268), isolated from an oil-producing well, was identified as a Thermoanaerobacter strain that was phenotypically related to T. finnii. Both SEBR 5268 and T. finnii oxidized H2 by reducing thiosulfate to sulfide using yeast extract as growth substrate. H2 oxidation in the presence of thiosulfate was significant at the end of the exponential growth of SEBR 5268 and was maintained during the lysis phase. In the absence of thiosulfate, H2 was inhibitory for both strains. The role of H2 consumption by these bacteria is discussed with regard to their metabolism on organic compounds.