Thermoanaerobacter uzonensis sp. nov., an anaerobic thermophilic bacterium isolated from a hot spring within the Uzon Caldera, Kamchatka, Far East Russia

Several strains of heterotrophic, anaerobic thermophilic bacteria were isolated from hot springs of the Uzon Caldera, Kamchatka, Far East Russia. Strain JW/IW010(T) was isolated from a hot spring within the West sector of the Eastern Thermal field, near Pulsating Spring in the Winding Creek area. Cells of strain JW/IW010(T) were straight to slightly curved rods, 0.5 mum in width and variable in length from 2 to 5 mum and occasionally up to 15 mum, and formed oval subterminal spores. Cells stained Gram-negative, but were Gram-type positive. Growth was observed between 32.5 and 69 degrees C with an optimum around 61 degrees C (no growth occurred at or below 30 degrees C, or at or above 72 degrees C). The pH(60 degrees C) range for growth was 4.2-8.9 with an optimum at 7.1 (no growth occurred at or below pH(60 degrees C) 3.9, or at 9.2 or above). The shortest observed doubling-time at pH(60 degrees C) 6.9 and 61 degrees C was 30 min. Strain JW/IW010(T) was chemo-organotrophic; yeast extract, peptone, Casamino acids and tryptone supported growth. Yeast extract was necessary for the utilization of non-proteinaceous substrates, and growth was observed with inulin, cellobiose, maltose, sucrose, glucose, fructose, galactose, mannose, xylose, trehalose, mannitol, pyruvate and crotonate. The G+C content of the genomic DNA of strain JW/IW010(T) was 33.6 mol% (HPLC method). The major phospholipid fatty acids were iso-15 : 0 (53.5 %), 15 : 0 (11.8 %), 16 : 0 (7.3 %), 10-methyl 16 : 0 (7.3 %) and anteiso-15 : 0 (5.3 %). 16S rRNA gene sequence analysis placed strain JW/IW010(T) in the genus Thermoanaerobacter of the family 'Thermoanaerobacteriaceae' (Firmicutes), with Thermoanaerobacter sulfurigignens JW/SL-NZ826(T) (97 % 16S rRNA gene sequence similarity) and Thermoanaerobacter kivui DSM 2030(T) (94.5 %) as the closest phylogenetic relatives with validly published names. The level of DNA-DNA relatedness between strain JW/IW010(T) and Thermoanaerobacter sulfurigignens JW/SL-NZ826(T) was 64 %. Based on the physiological, phylogenetic and genotypic data, strain JW/IW010(T) represents a novel taxon, for which the name Thermoanaerobacter uzonensis sp. nov. is proposed. The type strain is JW/IW010(T) (=ATCC BAA-1464(T)=DSM 18761(T)). The effectively published strain, 1501/60, of 'Clostridium uzonii' [Krivenko, V. V., Vadachloriya, R. M., Chermykh, N. A., Mityushina, L. L. & Krasilnikova, E. N. (1990). Microbiology (English translation of Mikrobiologiia) 59, 741-748] had approximately 88.0 % DNA-DNA relatedness with strain JW/IW010(T) and was included in the novel taxon.