Caloramator quimbayensis sp. nov., an anaerobic, moderately thermophilic bacterium isolated from a terrestrial hot spring

An anaerobic, moderately thermophilic, terminal-spore-forming bacterium, designated strain USBA A^T, 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 A^T were Gramstain- 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 A^T 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 A^T 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 A^T was inhibited by ampicillin, chloramphenicol, kanamycin, penicillin and streptomycin (each at 10 mg ml^-1). The predominant fatty acids were iso-C_15:0, C_16:0 and iso-C_17:0 and the genomic DNA G+C content was 32.6 mol%. 16S rRNA gene sequence analysis indicated that strain USBA A^T belonged in the phylum Firmicutes and that its closest relative was Caloramator viterbiensis JW/MS-VS5^T (95.0% sequence similarity). A DNA-DNA relatedness value of only 30% was recorded in hybridization experiments between strain USBA A^T and Caloramator viterbiensis DSM 13723^T. Based on the phenotypic, chemotaxonomic and phylogenetic evidence and the results of the DNA-DNA hybridization experiments, strain USBA A^T represents a novel species of the genus Caloramator, for which the name Caloramator quimbayensis sp. nov. is proposed. The type strain is USBA A^T (5CMPUJ U833^T =DSM 22093^T).