Caloramator viterbensis sp nov., a novel thermophilic, glycerol-fermenting bacterium isolated from a hot spring in Italy

A moderately thermophillic, anaerobic bacterium, strain JW/MS-VS5(T), was isolated from a mixed sediment/water sample of a hot spring at Bagnaccio (near Viterbo, Italy). The cells of this organism were straight to slightly curved rods, 0.4-0.6 x 2.0-3.0 mum in dimension. Cells occurred singly and stained Gram-positive. The temperature range for growth at pH(25C) 6.0 was 33-64 degreesC, the optimum being 58 degreesC. The pH(25C) range for growth was from 5.0 to 7.8, the optimum being 6.0-6.5. The substrates utilized included glycerol, glucose, fructose, mannose, galactose, sucrose, cellobliose, lactose, starch and yeast extract. Acetate and 1,3-propanediol were the only detectable organic of glycerol fermentation; significant amounts of H-2 were produced during growth. The strain was unable to grow autotrophically in the presence of H-2 and CO2. The main products of glucose fermentation were CO2, H-2, acetate and ethanol. Single amino acids, including serine, glutamine, threonine, leucine, methionine, aspartate, valline and histidine (but not arginine), served as sources. Growth was completely inhibited by ampicillin, chloramphenicol, erythromycin, rifampicin and kanamycin at 100 mug ml(-1) and was retarded by streptomycin and tetracycline. The G+C content of the DNA was 32 mol% (HPLC). According to 16S rDNA sequence analysis, the isolate is located within the Gram-type positive Bacillus-Clostridium branch of the phylogenetic tree. On the basis of physiological properties and phylogenetic analysis, it is proposed that strain JW/MS-VS5(T) (the only, and type, strain) (= DSM 13723(T) = ATCC PTA 584(T)), constitutes the new species Caloramator viterbensis.