Aquabacterium lacunae sp. nov., isolated from a freshwater pond

A novel bacterial strain, designated KMB7T, isolated from a freshwater pond in Taiwan, was characterized using a polyphasic taxonomic approach. Cells were Gram-stain-negative, motile by means of a single polar flagellum, rod-shaped and formed cream colonies. Optimal growth occurred at 25 °C, pH 7, and in the absence of NaCl. Phylogenetic analyses based on 16S rRNA gene sequences and an up-to-date bacterial core gene set (92 protein clusters) indicated that strain KMB7Tis affiliated with species in the genus Aquabacterium . The 16S rRNA gene sequence similarity indicated that strain KMB7Tis closely related to species within the genus Aquabacterium (95.2–97.6 % sequence similarity) and is most similar to A. fontiphilum CS-6T(97.6 %), followed by A. parvum B6T(97.5 %). The average nucleotide identity and digital DNA–DNA hybridization identity between strain KMB7Tand the closely related strains were 74.6–78.0 % and 19.0–21.2 %, respectively. The major fatty acids of strain KMB7Twere summed feature 3 (C16 : 1 ω7cand/or C16 : 1 ω6c), C18 : 1 ω7cand C16 : 0. The polar lipid profile consisted of a mixture of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylserine, diphosphatidylglycerol and four unidentified phospholipids. The sole isoprenoid quinone was ubiquinone-8 (Q-8). Genomic DNA G+C content of strain KMB7Twas 65.4 %. On the basis of phenotypic and genotypic properties and phylogenetic inference, strain KMB7Tshould be classified in a novel species of the genus Aquabacterium , for which the nameAquabacterium lacunaesp. nov. is proposed. The type strain is KMB7T(=BCRC 81156T=LMG 30924T=KCTC 62867T).