An anaerobic, moderately thermophilic, terminal-spore-forming bacterium, designated strain USBA AT, was isolated from a terrestrial hot spring located at an altitude of 2683 m in the Andean region of Colombia (04° 50′ 14.0″ N 75° 32′ 53.4″ W). Cells of strain USBA AT were Gram-stain-positive, straight to slightly curved rods (0.9×2.5 µm), that were arranged singly or in pairs, and were motile by means of flagella. Growth occurred at 37–55 °C and pH 6.0–8.0, with a doubling time of 2 h under the optimal conditions (50 °C and pH 7.0). Glucose fermentation in strain USBA AT required yeast extract or peptone (each at 0.2 %, w/v). The novel strain fermented sugars, amino acids, Casamino acids, propanol, propionate, starch and dextrin, but no growth was observed on galactose, lactose, xylose, histidine, serine, threonine, benzoate, butyrate, lactate, pyruvate, succinate, methanol, ethanol, glycerol, casein, gelatin or xylan. The end products of glucose fermentation were formate, acetate, ethanol and lactate. Strain USBA AT did not grow autotrophically (with CO2 as carbon source and H2 as electron donor) and did not reduce thiosulfate, sulfate, elemental sulfur, sulfite, vanadium (V) or Fe (III) citrate. Growth of strain USBA AT was inhibited by ampicillin, chloramphenicol, kanamycin, penicillin and streptomycin (each at 10 µg ml−1). The predominant fatty acids were iso-C15 : 0, C16 : 0 and iso-C17 : 0 and the genomic DNA G+C content was 32.6 mol%. 16S rRNA gene sequence analysis indicated that strain USBA AT belonged in the phylum
Firmicutes
and that its closest relative was
Caloramator viterbiensis
JW/MS-VS5T (95.0 % sequence similarity). A DNA–DNA relatedness value of only 30 % was recorded in hybridization experiments between strain USBA AT and
Caloramator viterbiensis
DSM 13723T. Based on the phenotypic, chemotaxonomic and phylogenetic evidence and the results of the DNA–DNA hybridization experiments, strain USBA AT represents a novel species of the genus
Caloramator
, for which the name Caloramator quimbayensis sp. nov. is proposed. The type strain is USBA AT ( = CMPUJ U833T = DSM 22093T).
Aquabacterium tepidiphilum sp. nov., a moderately thermophilic bacterium isolated from a hot spring
