Sinirhodobacter hankyongi sp. nov., a novel denitrifying bacterium isolated from sludge

Abstract

A novel Gram-reaction-negative, facultative-aerobic, motile, non-spore-forming, oval-shaped and denitrifying bacterium, designated BO-81T, was isolated from sludge sampled in the Republic of Korea. This bacterium was investigated via a polyphasic approach to reveal its taxonomic position. The results of phylogenetic analysis based on 16S rRNA gene sequencing indicated that strain BO-81T belonged to the family Rhodobacteraceae and was related to the closest species Sinirhodobacter ferrireducens (98.8% sequence similarity), 'Sinorhodobacter hungdaonensis' (98.4 %), Rhodobacter lacus (97.8%), Sinorhodobacter populi (96.8%) and Rhodobacter maris (96.2%). The average nucleotide identity and DNA-DNA hybridization values between strain BO-81T and its closely related strains were 77.7-94.2% and 20.1-55.9%, respectively, indicating that BO-81T represents a novel species of the genus Sinirhodobacter. Growth occurred at 18-40°C on Reasoner's 2A medium in the presence of 0-7% NaCl (w/v) and at pH 6.0-9.0. Strain BO-81T was characterized chemotaxonomically as having ubiquinone 10 as its predominant respiratory quinone, summed feature 8 (C18:1 ω6c and/or C18:1 ω7c) as its major fatty acid and phosphatidylglycerol and phosphatidylethanolamine as its predominant polar lipids. The G+C content of the genomic DNA was 68.3 mol%. The results of physiological and biochemical tests allowed phenotypic differentiation of strain BO-81T from other Sinirhodobacter species with validly published names. Therefore, the isolate represented a novel species, for which the name Sinirhodobacter hankyongi sp. nov. (type strain BO-81T=KACC 19677T=LMG 30808T) is proposed.