Fusibacter ferrireducens sp. nov., an anaerobic, Fe(Ⅲ)- and sulphur-reducing bacterium isolated from mangrove sediment

An anaerobic, alkaliphilic, halotolerant, Gram-stain-positive and rod-shaped bacterium, designated Q10-2^T, was isolated from mangrove sediment sampled at the Jiulong river estuary, PR China. The cells of strain Q10-2^T were motile and 0.5×2-4 µm in size. Strain Q10-2^T grew at 8-45 °C (optimum, 32 °C), at pH 7.0-10.5 (optimum, pH 8.5) and in the presence of 0-6 % (w/v) NaCl (optimum, 3 %). It could use complex organic compounds and carbohydrates including d-fructose, d-galactose, d-glucose, d-mannitol, d-xylose, trehalose, lactose, maltose, sucrose and starch as carbon sources and electron donors. It could reduce sulphate, thiosulphate and elemental sulphur to sulphide, but not sulphite. Fe (Ⅲ) citrate, ferrihydrite, haematite and goethite in the presence of glucose as the electron donor were also reduced. Acetate, butyrate, ethanol, CO₂ and H₂ were end products of glucose fermentation. The predominant cellular fatty acids were composed of C_14 : 0, C_16 : 0 and summed features containing C_16 : 1 ω7c and/or iso-C_15 : 0 2-OH and iso-C_17 : 1 and/or anteiso-C_17 : 1 B. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the novel strain was most closely related to Fusibacter paucivorans DSM 12116^T (95.5 % sequence similarity). The genome size of strain Q10-2^T was 5.0 Mb, with a G+C content of 37.4 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain Q10-2^T and F. paucivorans DSM 12116^T were 69.1 and 21.8 %, respectively. The combined genotypic and phenotypic data showed that strain Q10-2^T represents a novel species of the genus Fusibacter, for which the name Fusibacter ferrireducens sp. nov. is proposed. The type strain is Q10-2^T (=MCCC 1A16257^T=KCTC 15906^T).