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, d esignated MV1075(T), was isolated from a deep-sea hydrothermal chimney samp le collected on the Mid-Atlantic Ridge. Cells were rod-shaped with a sheath -like outer structure, motile with polar flagella and stained Gramnegative. They appeared singly, in pairs or in short chains. The temperature range f or growth was 25-65 degreesC, with an optimum at 55 degreesC. Growth was ob served from ph 5 to ph 9, and the optimum ph was around 7. The salinity ran ge for growth was 15-70 g sea salt I-1 (corresponding to 10-45 g NaCl I-1), with an optimum at 30 g I-1 (20 g NaCl I-1). The isolate was able to grow on a broad spectrum of carbohydrates or complex proteinaceous substrates. S ulfur was not necessary for growth. Growth was inhibited by H-2, but, in pr esence 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 r RNA gene located the strain within the order Thermotogales, in the domain B acteria. On the basis of 165 rDNA sequence comparisons, in combination with morphological and physiological characteristics, it is proposed that the i solate should be described as a novel species of a new genus, Marinitoga ge n. nov., of which Marinitoga camini sp. nov, is the type species. The type strain is MV1075(T) (= CNCM 1-2413(T) = D5M 13578(T)).