- International Journal of Systematic and Evolutionary Microbiology
- Volume 48, Issue 1
f Sulfur-inhibited Thermosphaera aggregans sp. nov., a new genus of hyperthermophilic archaea isolated after its prediction from environmentally derived 16S rRNA sequences
- Authors: Robert Huber, Diana Dyba, Harald Huber, Siegfried Burggraf, Reinhard Rachel
- Author for correspondence: Robert Huber. Tel: +49 941 943 3182. Fax: +49 941 943 2403. e-mail: Robert.Huber@biologie.uni-regensburg.de
- Int J Syst Evol Microbiol, January 1998 48: 31-38, doi: 10.1099/00207713-48-1-31
- Subject: Systematic Bacteriology
- Published Online:
Recently, a new procedure was developed which allowed for the first time the isolation of a hyperthermophilic archaeum tracked by 16S rRNA analysis from a terrestrial hot solfataric spring (‘Obsidian Pool’, Yellowstone National Park, WY, USA). This novel isolate is characterized here. Cells are round cocci with a diameter of 0·2--0·8 μm, occurring singly, in pairs, short chains and in grape-like aggregates. The aggregates exhibit a weak bluish-green fluorescence under UV radiation at 420 nm. The new isolate is an anaerobic obligate heterotroph, using preferentially yeast extract for growth. The metabolic products include CO2, H2, acetate and isovalerate. Growth is observed between 65 and 90 °C (optimum: 85 °C), from pH 5·0 to 7·0 (optimum: 6·5) and up to 0·7% NaCI. The apparent activation energy for growth is about 149 kJ mol-1. Elemental sulfur or hydrogen inhibits growth. The core lipids consist mainly of acyclic and cyclic glycerol diphytanyl tetraethers. The cell envelope contains a cytoplasmic membrane covered by an amorphous layer of unknown composition; there is no evidence for a regularly arrayed surface-layer protein. The G+C content is 46 mol%. On the basis of 16S rRNA sequence comparisons in combination with morphological, physiological and biochemical properties, the isolate represents a new genus within the Desulfurococcaceae, which has been named Thermosphaera. The type species is Thermosphaera aggregans, the type strain is isolate M11TLT (= DSM 11486T).
The EMBL accession number for the M11TLT 16S rRNA gene sequence reported in this paper is X99556.
© 1998, International Union of Microbiological Societies | Published by the Microbiology Society
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