Xiashengella succiniciproducens gen. nov., sp. nov., a succinate-producing bacterium isolated from an anaerobic digestion tank in the family Marinilabiliaceae of the order Bacteroidales.

A strictly anaerobic, motile bacterium, designated as strain Ai-910, was isolated from the sludge of an anaerobic digestion tank in China. Cells were Gram-stain-negative rods. Optimal growth was observed at 38 °C (growth range 25-42 °C), pH 8.5 (growth range 5.5-10.5), and under a NaCl concentration of 0.06% (w/v) (range 0-2.0%). Major cellular fatty acids were iso-C and anteiso-C. The respiratory quinone was MK-7. Using xylose as the growth substrate, succinate was produced as the fermentation product. Phylogenetic analysis based on the 16 S rRNA gene sequences indicated that strain Ai-910 formed a distinct phylogenetic lineage that reflects a new genus in the family Marinilabiliaceae, sharing high similarities to Alkaliflexus imshenetskii Z-7010 (92.78%), Alkalitalea saponilacus SC/BZ-SP2 (92.51%), and Geofilum rubicundum JAM-BA0501 (92.36%). Genomic similarity (average nucleotide identity and digital DNA-DNA hybridization) values between strain Ai-910 and its phylogenetic neighbors were below 65.27 and 16.90%, respectively, indicating that strain Ai-910 represented a novel species. The average amino acid identity between strain Ai-910 and other related members of the family Marinilabiliaceae were below 69.41%, supporting that strain Ai-910T was a member of a new genus within the family Marinilabiliaceae. Phylogenetic, genomic, and phenotypic analysis revealed that strain Ai-910 was distinguished from other phylogenetic relatives within the family Marinilabiliaceae. The genome size was 3.10 Mbp, and the DNA G + C content of the isolate was 42.8 mol%. Collectively, differences of the phenotypic and phylogenetic features of strain Ai-910 from its close relatives suggest that strain Ai-910 represented a novel species in a new genus of the family Marinilabiliaceae, for which the name Xiashengella succiniciproducens gen. nov., sp. nov. was proposed. The type strain of Xiashengella succiniciproducens is Ai-910 (= CGMCC 1.17893 = KCTC 25,304).