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

A novel bacterial strain, designated KMB7(T), 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 degrees C, pH 7, and in the absence of NaCl. Phylogenetic analyses based on 165 rRNA gene sequences and an up-to-date bacterial core gene set (92 protein clusters) indicated that strain KMB7(T) is affiliated with species in the genus Aquabacterium. The 165 rRNA gene sequence similarity indicated that strain KMB7(T) is closely related to species within the genus Aquabacterium (95.2 97.6% sequence similarity) and is most similar to A. fontiphilum CS-6(T) (97.6 %). followed by A. parvum B6(T) (97.5 %). The average nucleotide identity and digital DNA-DNA hybridization identity between strain KMB7(T) and the closely related strains were 74.6-78.0% and 19.0-21.2%, respectively. The major fatty acids of strain KMB7(T) were summed feature 3 (C-16:1, omega 7c and/or C-16:1 omega 6c), C-18:1, omega 7c and C-16:0. 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 KMB7(T) was 65.4%. On the basis of phenotypic and genotypic properties and phylogenetic inference, strain KMB7(T) should be classified in a novel species of the genus Aquabacterium, for which the name Aquabacterium lacunae sp. nov. is proposed. The type strain is KMB7(T) (=BCRC 81156(T)=LMG 30924(T)=KCTC 62867(T)).