A novel sulfate-reducing bacterium, designated C1TLV30(T), was isolated from wood falls at a depth of 1693 m in the Mediterranean Sea. Cells were motile vibrios (2-4 × 0.5 µm). Strain C1TLV30(T) grew at temperatures between 15 and 45 °C (optimum 30 °C) and at pH 5.4-8.6 (optimum 7.3). It required NaCl for growth (optimum at 25 g NaCl l(-1)) and tolerated up to 80 g NaCl l(-1). Strain C1TLV30(T) used as energy sources: lactate, fumarate, formate, malate, pyruvate and ethanol. The end products from lactate oxidation were acetate, H(2)S and CO(2) in the presence of sulfate as terminal electron acceptor. Besides sulfate, thiosulfate and sulfite were also used as terminal electron acceptors, but not elemental sulfur, fumarate, nitrate or nitrite. Strain C1TLV30(T) possessed desulfoviridin and was piezophilic, growing optimally at 10 MPa (range 0-30 MPa). The membrane lipid composition of this strain was examined to reveal an increase in fatty acid chain lengths at high hydrostatic pressures. The G+C content of the genomic DNA was 49.6 % and the genome size was estimated at 3.5 ± 0.5 Mb. Phylogenetic analysis of the SSU rRNA gene sequence indicated that strain C1TLV30(T) was affiliated to the genus Desulfovibrio with Desulfovibrio profundus being its closest phylogenetic relative (similarity of 96.4 %). On the basis of SSU rRNA gene sequence comparisons and physiological characteristics, strain C1TLV30(T) ( = DSM 21447(T) = JCM 1548(T)) is proposed to be assigned to a novel species of the genus Desulfovibrio, Desulfovibrio piezophilus sp. nov.
