A genomic analysis of the archaeal system Ignicoccus hospitalis-Nanoarchaeum equitans

Sequencing of the complete genome of Ignicoccus hospitalis gives insight into its association with another species of Archaea, Nanoarchaeum equitans

Thiobacillus cuprinus sp. nov., a Novel Facultatively Organotrophic Metal-Mobilizing Bacterium

Five strains of mesophilic, facultatively organotrophic, ore-leaching eubacteria were isolated from solfatara fields in Iceland and a uranium mine in the Federal Republic of Germany. The new organisms are aerobic gram-negative rods. They can use sulfidic ores or elemental sulfur as sole energy source, indicating that they belong to the genus Thiobacillus. Alternatively, they grow on organic substrates such as yeast extract, peptone, and pyruvate. In contrast to the other leaching bacteria known so far, the new isolates are unable to oxidize ferrous iron. They consist of extreme and moderate acidophiles growing optimally at pH 3 and 4, respectively. The extreme acidophiles showed leaching characteristics similar to those shown by Thiobacillus ferrooxidans, while the moderate acidophiles exhibited a pronounced preference for copper leaching on some chalcopyrite ores. The G+C content of the DNA is between 66 and 69 mol%, depending on the isolate. In DNA-DNA hybridization experiments, the new strains showed homologies among each other of >70%, indicating that they belong to the same species. No significant DNA homology to Thiobacillus reference strains was detectable. Therefore, the new isolates represent a new species of Thiobacillus, which we name Thiobacillus cuprinus. Isolate Hö5 is designated as the type strain (DSM 5495)

The role of hyperthermophilic prokaryotes in oil ¢elds. In: Microbial Biosystems: new Frontiers

ABSTRACT Deep geothermally heated oil stratifications represent newly recognized non-volcanic islands of microbial life at extremely high temperatures, some 3,500 m below the surface. Samples of produced fluids contain high concentrations of various anaerobic extremely thermophilic and hyperthermophilic archaea and bacteria, indicating the presence of complex microbial communities in situ. The isolates consist of heterotrophs and facultative and obligate chemolithoautotrophs, some of which are able to use crude oil in their energyyielding reactions. They belong to the genera Archaeoglobus, Thermococcus, Pyrococcus, Methanococcus, Methanobacterium, Thermotoga, Thermosipho, and Thermodesulfobacterium. Most isolates are members of species already known from hot springs and hydrothermal vents. They may have entered the reservoirs through natural routes such as faults and oil seeps or by sea water injection. A great deal are sulfidogens and may, therefore, participate in reservoir "souring" at temperatures previously considered too high for biochemical reactions

Marinamoeba thermophila, a new marine heterolobosean amoeba growing at 50 degrees C.

Two amoeba strains were isolated from marine sediment taken at the same place with 18 months interval from a region of the sea floor heated by extended submarine hot springs and fumaroles. These thermophilic amoebae grow at temperatures up to 50 degrees C. Sequences of the internal transcribed spacer demonstrated that the two strains belong to the same species and are different from any genus for which sequences are known. Phylogeny using small subunit ribosomal RNA places the amoeba in the Heterolobosea. Their closest relatives are the hypersaline flagellate Pleurostomum flabellatum and the hypersaline amoeba Tulamoeba peronaphora. The freshwater amoeboflagellate genera Naegleria and Willaertia belong to the same phylogenetic clade in the Vahlkampfiidae. The new marine species does not transform into flagellates. It forms cysts, which are round to ellipsoidal with few pores. Because of their unique place in the molecular phylogenetic tree, and because there is no morphologically identical species found in the literature, these isolates are considered to be a new species and a new genus, Marinamoeba thermophila