A bacterial strain, designated TCH3-2T, was isolated from the rhizosphere of tomato plant grown at Dong-A University Agricultural Experiment Station, Republic of Korea. The strain was Gram-stain-negative, obligate aerobic, orange yellow-coloured, motile by gliding and short rod-shaped. Strain TCH3-2 T only grew on 1/2 tryptic soy agar and Luria-Bertani agar among the media tested, with optimum growth at 28 °C and pH 7. Salt of 1 % NaCl was necessary to support the growth of TCH3-2T. Strain TCH3-2T produced flexirubin-type pigments. The predominant cellular fatty acids were iso-C15 : 0 (55.6 %), iso-C17 : 0 3-OH (17.9 %), summed feature 9 (comprising C16 : 0 10-methyl and/or iso-C17 : 1 ω9c; 10.5 %), iso-C15 : 0 3-OH (4.8 %) and anteiso-C15 : 0 (2.3 %). The major menaquinone was menaquinone-6 and the major polar lipids were phosphatidylethanolamine, five unknown aminolipids and three unknown lipids. Phylogenetic analysis based on 16S rRNA sequences indicated that TCH3-2T was closely related to Flavobacterium ummariense DS-12T (95.16 %), Flavobacterium marinum SW105T (95.14 %) and Flavobacterium viscosus YIM 102796T (94.54 %). The draft genome of TCH3-2T comprised ca. 2.8 Mb with a G+C content of 34.61 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between TCH3-2T and closely related Flavobacterium species showed that it belongs to a distinct species. Furthermore, the results of morphological, physiological and biochemical tests allowed further phenotypic differentiation of TCH3-2T from its closest relatives. Thus, chemotaxonomic characteristics together with phylogenetic affiliation illustrate that TCH3-2T represents a novel species of the genus Flavobacterium, for which the name Flavobacterium dauae sp. nov. (type strain TCH3-2T=KACC 19054T=JCM 34025T) is proposed.
Keywords: Flavobacterium dauae sp. nov.; growth promotion; tomato rhizosphere.