A novel strictly anaerobic sulfate-reducing diazotrophic bacterium Fundidesulfovibrio terrae sp. nov., isolated from paddy soil

A strictly anaerobic sulfate-reducing strain, designated SG127 T , was isolated from paddy soil. SG127 T showed the highest 16S rRNA gene sequence similarity to the type strain of Fundidesulfovibrio magnetotacticus (98.2 %). A phylogenetic tree based on 16S rRNA gene sequences indicated that SG127 T clustered with members of the genus Fundidesulfovibrio . Growth of SG127 T was observed at 20–37 °C (optimum, 30 °C), pH 5.5–9.0 (optimum, 7.0–8.0) and with 0–0.2 % (w/v) NaCl (optimally without NaCl). SG127 T contained MK-7 as the only menaquinone and anteiso-C 15 : 0 , anteiso-C 17 : 1 ω9 c , C 18 : 0 , iso-C 14 : 0, iso-C 15 : 0 , iso-C 16:0, iso-C 16 : 1 H, iso-C 18 : 1 H and summed feature nine as the major fatty acids. The genomic DNA G+C content of SG127 T was 64.6 %. The average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between SG127 T and the closely related Fundidesulfovibrio magnetotacticus were 78.5% and 23.2 %, respectively, which were lower than the cut-off values (ANI 95–96% and dDDH 70 %) for prokaryotic species delineation. SG127 T had desulfoviridin, possessed nitrogen fixation genes ( nifHDK ) and actively fixed nitrogen according to the acetylene reduction assay. On the basis of these results, strain SG127 T represents a novel species of the genus Fundidesulfovibrio , for which the name Fundidesulfovibrio terrae sp. nov. is proposed. The type strain is SG127 T (= GDMCC 1.3137 T = JCM 35589 T ).