RESUMEN
To obtain amino acid-utilizing sulfate reducers, enrichment culture was carried out with a medium containing Casamino acids and sulfate and inoculated with coastal marine sediment from the eutrophic Tokyo Bay, Japan. A sulfate reducer, designated strain C/L2(T), was isolated from the sulfide-producing enrichment culture after further enrichment with lactate and sulfate by means of the agar shake dilution method. Cells of strain C/L2(T) were vibrio-shaped, Gram-negative, motile rods (0.7-1.0 mum wide and 1.0-3.5 mum long) with single polar flagella. The optimum temperature for its growth was 37 degrees C, the optimum pH was around 7.5 and the optimum NaCl concentration was 20-25 g l(-1). Hydrogen, formate, lactate, pyruvate, fumarate, malate, succinate, ethanol, propanol, glycerol, glycine, alanine, serine, aspartate, Casamino acids, peptone and yeast extract were used as electron donors. Sulfate, sulfite and thiosulfate each served as an electron acceptor, but elemental sulfur, nitrate, fumarate, acrylate and 2,4,6-tribromophenol did not. Disproportionation of thiosulfate was not observed. Desulfoviridin, c-type cytochromes and catalase were present. The major respiratory quinone was MK-6(H(2)). The G+C content of the genomic DNA was 46.2 mol%. Comparisons based on 16S rRNA gene sequences and on dissimilatory sulfite reductase gene sequences clearly showed that strain C/L2(T) belonged to the genus Desulfovibrio: its closest relatives were the uncharacterized Desulfovibrio sp. strain TBP-1 (16S rRNA gene sequence similarity of 99.4 %) and Desulfovibrio acrylicus DSM 10141(T) (16S rRNA gene sequence similarity of 98.7 %). The level of DNA-DNA hybridization with Desulfovibrio acrylicus DSM 10141(T) was 10.3 %. On the basis of the data from this study and the physiological and phylogenetic differences that exist between the isolate and Desulfovibrio acrylicus, strain C/L2(T) represents a novel species of the genus Desulfovibrio, for which the name Desulfovibrio marinisediminis sp. nov. is proposed. The type strain is C/L2(T) (=NBRC [corrected] 101113(T)=JCM 14577(T)=DSM 17456(T)).
