sp. nov., a sulphate-reducing magnetotactic bacterium, isolated from sediments and freshwater of a pond.

A sulphate-reducing magnetotactic bacterium, designated strain FSS-1, was isolated from sediments and freshwater of Suwa Pond located in Hidaka, Saitama, Japan. Strain FSS-1 was a motile, Gram-negative and curved rod-shaped bacterium that synthesizes bullet-shaped magnetite (FeO) nanoparticles in each cell. Strain FSS-1 was able to grow in the range of pH 6.5-8.0 (optimum, pH 7.0), 22-34 °C (optimum, 28 °C) and with 0-8.0 g l NaCl (optimum, 0-2.0 g l NaCl). Strain FSS-1 grew well in the presence of 50 µM ferric quinate as an iron source. The major fatty acids were anteiso-C, iso-C and anteiso-C. The major menaquinone was MK-7 (H). Strain FSS-1 contained desulfoviridin, cytochrome and catalase, but did not contain oxidase. Strain FSS-1 used fumarate, lactate, pyruvate, malate, formate/acetate, succinate, tartrate, ethanol, 1-propanol, peptone, soytone and yeast extract as electron donors, while the strain used sulphate, thiosulphate and fumarate as electron acceptors. Fumarate was fermented in the absence of electron acceptors. Analysis of the 16S rRNA gene sequence showed that strain FSS-1 is a member of the genus . The gene sequence showed 96.7, 95.0, 92.0, 91.2 and 91.4% similarities to the most closely related members of the genera B7-43, BSY, DSM 107105, ThAc01 and RS-1, respectively. The DNA G+C content of strain FSS-1 was 67.5 mol%. The average nucleotide identity value between strain FSS-1 and B7-43 was 80.7 %. Therefore, strain FSS-1 represents a novel species within the genus , for which the name sp. nov. is proposed (=JCM 32405=DSM 110007).