Marinitoga camini gen. nov., sp. nov., a rod-shaped bacterium belonging to the order Thermotogales, isolated from a deep-sea hydrothermal vent.

A thermophilic, anaerobic, chemo-organotrophic sulfur-reducing bacterium, designated MV1075T, was isolated from a deep-sea hydrothermal chimney sample collected on the Mid-Atlantic Ridge. Cells were rod-shaped with a sheath-like outer structure, motile with polar flagella and stained Gram-negative. They appeared singly, in pairs or in short chains. The temperature range for growth was 25-65 degrees C, with an optimum at 55 degrees C. Growth was observed from pH 5 to pH 9, and the optimum pH was around 7. The salinity range for growth was 15-70 g sea salt l(-1) (corresponding to 10-45 g NaCl l(-1)), with an optimum at 30 g l(-1) (20 g NaCl l(-1)). The isolate was able to grow on a broad spectrum of carbohydrates or complex proteinaceous substrates. Sulfur was not necessary for growth. Growth was inhibited by H2, but, in presence of sulfur, this inhibition was removed and H2S was produced. The G+C content of the genomic DNA was 29 mol %. Phylogenetic analyses of the 16S rRNA gene located the strain within the order Thermotogales, in the domain Bacteria. On the basis of 16S rDNA sequence comparisons, in combination with morphological and physiological characteristics, it is proposed that the isolate should be described as a novel species of a new genus, Marinitoga gen. nov., of which Marinitoga camini sp. nov. is the type species. The type strain is MV1075T (= CNCM 1-2413T = DSM 13578T).