Chitinibacter bivalviorum sp. nov., isolated from the gut of the freshwater mussel anodonta arcaeformis

A novel Gram-stain-negative, aerobic, rod-shaped bacterium with a single polar flagellum, designated strain 2T18^T, was isolated from the gut of the freshwater mussel Anodonta arcaeformis collected in the Republic of Korea. Phylogenetic analyses based on 16S rRNA gene sequences showed that the strain belonged to the genus Chitinibacter. Strain 2T18^T formed a monophyletic clade with Chitinibacter fontanus KCTC 42982^T, C. tainanensis KACC 11706^T and C. alvei KCTC 23839^T, with sequence similarities of 98.5, 98.4 and 95.9%, respectively. Strain 2T18^T exhibited optimal growth at 30 °C, at pH 8 and with 0.5% (w/v) NaCl. The major isoprenoid quinone was ubiquinone-8 (Q-8). The predominant fatty acids were summed feature 3 (C_16:1 ω6c and/ or C_16:1 ω7c) and C_16:0. The polar lipids comprised phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, one unidentified lipid, three unidentified phospholipids and two unidentified aminophospholipids. The G+C content of the genomic DNA was 50.6 mol%. The average nucleotide identity and digital DNA–DNA hybridization values between strains 2T18^T and C. fontanus KCTC 42982^T were below the thresholds used for the delineation of a novel species. Based on the phylogenetic, phenotypic, chemotaxonomic and genotypic characteristics, strain 2T18^T represents a novel species of the genus Chitinibacter, for which the name Chitinibacter bivalviorum sp. nov. is proposed. The type strain is 2T18^T (=KCTC 72821^T=CCUG 74764^T).