A Desulfovibrio strain physiologically similar to and phylogeneticall related to "D. caledoniensis" SEBR 7250, D. portus MSL79, and D. dechloracetivorans ATCC 700912 (96.9, 95.9, and 95.8% similarity of the 16S rRNA gen sequences, respectively) was isolated from marine biofouling in the coastal zone of the South China Sae (Nha Trang, South Vietnam). The cells of strain ME were gram-negative motile vibrios (0.4-0.6 x 1.3-2 μm) with a single flagellum. The strain grew at 20 to 39 degrees C (growth optimum at 34-37 degrees C), pH 5.8 to 8.5 (pH optimum at 6.8-7.5), and salinity from 0.08 to 1.1 M Na+ (optimum at 0.2-0.3 M Na+). In the presence of sulfate, the strain grew autotrophically with hydrogen or on lactate, formate, pyruvate, fumarate, and malate. Weak growth occurred on succinate, glycerol, and fructose. In the absence of sulfate, the strain was able to ferment pyruvate, malate (weakly), but not lactate. Sulfate, sulfite, thiosulfate, elemental sulfur, and dimethyl sulfoxide were used as electron acceptors. Vitamins and yeast extract were not required for growth. The G+C content was 52.4 mol %. Predominant fatty acids were C18:0 (13.9%), C16:0 (9.6%), iso-C16:0 (9.5%), C18: 1w7 (8.8%), anteiso-C15:0 (8.1%), and iso-C 17:1 (7.2%). The fatty acid composition was close to that of D. dechloracetivorans BO and has some similarity to that of D. portus. Based on its genotypic and phenotypic characteristics, strain ME maybe considered as a new species, for which the name Desulfovibrio hontrensis sp. nov. is proposed.