A novel non-motile, Gram-staining-negative, yellow-pigmented bacterium, designated CT348(T), isolated from the ectorhizosphere of an organic olive tree in Spain and characterised as an efficient plant growth promoting bacterium, was investigated to determine its taxonomic status. The isolate grew best in a temperature range of 5-35°C, at pH 5.0-8.0 and with 0-1% (w/v) NaCl. Chemotaxonomic and molecular characteristics of the isolate matched those described for members of the genus Chryseobacterium. The DNA G+C content of the novel strain was 38.2mol%. The strain contained a polyamine pattern with sym-homospermidine as the major compound and produced flexirubin-type pigments. MK-6 was the dominant menaquinone and the major cellular fatty acids were iso-C15:0, C17:1ω9c, iso-C17:0 3-OH and iso-C15:0 2-OH. The main polar lipids were phosphatidylethanolamine and several unidentified lipids and aminolipids. The 16S rRNA gene showed 92.2-97.8% sequence identity with the members of the genus Chyseobacterium. Based on the phenotypic traits and DNA-DNA hybridizations with the type strains of the most closely related species, the isolate is shown to represent a novel species, Chyseobacterium oleae, type strain CT348(T) (=DSM 25575 =CCUG 63020). Emended descriptions of the genus Chryseobacterium and C. daecheongense, C. gambrini, C. gleum, C. joostei, C. jejuense, C. luteum, C. shigense, C. taiwanense, C. ureilyticum and C. vrystaatense are also proposed.