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A Gram-negative, obligately anaerobic, non-spore-forming, long rod-shaped bacterium strain P2(T) was isolated from the offshore mangrove sediment of the South China Sea. Growth was observed at between 22 and 39 °C, with an optimum at 35 °C. The pH range for growth was 5.0-8.5, with an optimum around pH 7.0-7.5. Salt tolerance was determined between 0.2 and 3.5% (w/v), optimum at 0.5-1.0%. Catalase and oxidase activities were negative. Strain P2(T) utilized cysteine, lactate, pyruvate, yeast extract or H(2)/CO(2)+acetate as electron donors, and sulfate or sulfite as electron acceptors. Metabolism was strictly fermentative. The main organic fermentation products were propionate, acetate and succinate. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain P2(T) formed a distinct evolutionary lineage within the family Marinilabiliaceae. Strain P2(T) was most closely related to members of the genera Alkaliflexus (92.0% 16S rRNA gene sequence similarity), Marinilabilia (91.7%) and Anaerophaga (89.9%) of the family Marinilabiliaceae. The DNA G+C content of the novel strain was 44.2 ± 1.0 mol%. The dominant fatty acids of strain P2(T) were iso-C(15:0) (33.5%), anteiso-C(15:0) (18.9%), C(16:0) (5.4%), C(16:0) 3-OH (7.7%) and iso-C(17:0) 3-OH (13.3%). The respiratory quinone was menaquinone 7 (100% of total quinone) and the major polar lipid was phosphatidylethanolamine. Strain P2(T) was distinguishable from members of phylogenetically related genera by differences in several phenotypic properties. On the basis of phylogenetic, phenotypic and physiological evidence, a novel genus, Mangroviflexus, is proposed to harbour strain P2(T) ( = CGMCC 1.5167(T) = DSM 24214(T)) which is described as the type strain of a novel species, Mangroviflexus xiamenensis gen. nov., sp. nov.

A taxonomic study was carried out on strain P1(T), which was isolated from mangrove sediment samples collected from Qinglan Port (Hainan, China). Cells were curved rods, that were motile, with a single polar flagellum. The strain was non-spore-forming with a cell size of 0.6×1.5-2.2 µm. Catalase and oxidase activities were not detected. Growth was observed in the temperature range 22-44 °C (optimum, 35-40 °C) and pH range 5.5-8.5 (optimum, pH 7.0). NaCl was required for growth and tolerated at up to 3.5% (w/v) (optimum, 0.5%). Strain P1(T) utilized hydrogen, succinate, L-malate, citrate, oxalate, DL-lactate, pyruvate, or cysteine as electron donors, and sulfate or sulfite as electron acceptors. Fermentation products from pyruvate were acetate, H(2) and CO(2). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain P1(T) formed a distinct evolutionary lineage within the family Desulfovibrionaceae. Strain P1(T) was most closely related to members of the genera Desulfovibrio (92.0-94.3% 16S rRNA gene sequence similarity), Desulfocurvus (91.1%), Bilophila (87.9%) and Lawsonia (86.0%) of the family Desulfovibrionaceae. The DNA G+C content of strain P1(T) was 64.5 mol% and the major cellular fatty acids were iso-C(15:0) (18.8%), anteiso-C(15:0) (5.0%), C(16:0) (14.2%) and iso-C(17:1)ω9c (24.4%). The predominant menaquinone was MK-7 (97%). Major polar lipids were phosphatidylcholine, phosphatidylethanolamine and phosphatidylglycerol. Strain P1(T) was distinguishable from members of phylogenetically related genera by differences in several phenotypic properties. On the basis of the phenotypic and phylogenetic data, strain P1(T) represents a novel species of a new genus, for which the name Desulfobaculum xiamenensis gen. nov., sp. nov. is proposed. The type strain of Desulfobaculum xiamenensis is P1(T) (=CGMCC 1.5166(T)=DSM 24233(T)).