A novel Gram-stain-negative, aerobic, heterotrophic, stalked and capsulated bacterium with potential denitrification ability, designated strain TAR-002T, was isolated from deep seafloor sediment in Japan. Colonies lacked lustre, and were viscous and translucent white. The ranges of temperature, pH and salt concentration for growth were 8–30 °C, pH 6.0–10.0 and 1–3 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences confirmed that strain TAR-002T belongs to the genus Brevundimonas of the class Alphaproteobacteria . Levels of similarity between the 16S rRNA gene sequence of strain TAR-002T and those of the type strains of species of the genus Brevundimonas were 93.5–98.9 %; the most closely related species was Brevundimonas basaltis . In DNA–DNA hybridization assays between strain TAR-002T and its phylogenetic neighbours, Brevundimonas lenta DS-18T, B. basaltis J22T, Brevundimonas subvibrioides ATCC 15264T and Brevundimonas alba DSM 4736T, mean hybridization levels were 6.4–27.7 %. The G+C content of strain TAR-002T was 70.3 mol%. Q-10 was the major respiratory isoprenoid quinone. The major fatty acids were C18 : 1ω7c and C16 : 0, and the presence of 1,2-di-O-acyl-3-O-[d-glucopyranosyl-(1→4)-α-d-glucopyranuronosyl]glycerol (DGL) indicates the affiliation of strain TAR-002T with the genus Brevundimonas . On the basis of biological characteristics and 16S rRNA gene sequence comparisons, strain TAR-002T is considered to represent a novel species of the genus Brevundimonas , for which the name Brevundimonas denitrificans sp. nov. is proposed; the type strain is TAR-002T ( = NBRC 110107T = CECT 8537T).