Rhizobacter profundi sp. nov., isolated from freshwater sediment

Abstract

Three bacterial strains, designated DS48-6-5T, DS48-6-7 and DS48-6-9, were isolated from a sediment sample taken from Daechung Reservoir (Republic of Korea) at a water depth of 48 m. Cells of the strains were Gram-stain-negative, aerobic, rod-shaped and motile with a single polar flagellum. Comparative 16S rRNA gene sequence studies showed that the three isolates had clear affiliation with Betaproteobacteria and the closest relatives were Rhizobacter bergeniae KCTC 32299T, Rhizobacter dauci DSM 11587T and Rhizobacter fulvus KCTC 12591T with 97.2-97.9% 16S rRNA gene sequence similarities; the 16S rRNA gene sequence similarities between the three strains were 99.5-100%. The only isoprenoid quinone of the three strains was ubiquinone-8, and the major fatty acids were summed feature 3 (C16: 1ω6c and/or C16: 1ω7c) and C16: 0. The G+C content of the genomic DNA of strains DS48-6-5T, DS48-6-7 and DS48-6-9 was 66.7, 67.0 and 66.8 mol%, respectively. DNA-DNA hybridization values of the novel strains with R. bergeniae KCTC 32299T, R. dauci DSM 11587T and R. fulvus KCTC 12591T were 19.3-48.5%. Based on the evidence from this taxonomic study using a polyphasic approach, it is proposed that strains, DS48-6-5T, DS48-6-7 and DS48-6-9, represent a novel species of the genus Rhizobacter, for which the name Rhizobacter profundi sp. nov. is proposed. The type strain is DS48-6-5T (=KCTC 42645T=NBRC 111169T).