Thermoanaerobacterium aotearoense sp nov, a slightly acidophilic, anaerobic thermophile isolated from various hot springs in New Zealand, and emendation of the genus Thermoanaerobacterium

Six moderately acidophilic, thermophilic bacterial strains with similar properties were isolated from geothermally heated water and sediment samples collected in New Zealand, These Gram stain-negative but Gram type-positive, rod-shaped bacteria formed oval terminal endospores, The cells were peritrichously flagellated and exhibited tumbling motility, At 60 degrees C the pH range for growth was 3.8 to 6.8, and the optimum pH was 5.2 when the organisms were grown with xylose, At pH 5.2 the temperature range for growth was 35 to 66 degrees C, and the optimum temperature was 60 to 63 degrees C, The fermentation products from glucose or xylose were ethanol, acetate, lactate, CO2, and H-2. The DNA G+C content was 34.5 to 35 mol%, On the basis of properties such as formation of elemental sulfur from thiosulfate, growth at acidic pH values at elevated temperatures, and the results of a 16S rRNA sequence comparison performed with previously validly published species belonging to the genus Thermoanaerobacterium, we propose that strain JW/SL-NZ613(T) (T = type strain) and five similar strains isolated from samples collected in New Zealand represent a new species, Thermoanaerobacterium aotearoense, Strain JW/SL-NZ613(T) (= DSM 10170) is the type strain of this species.