Flavobacterium dauae sp. nov., isolated from rhizosphere soil of a tomato plant

Abstract

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.

The Plant-Associated Flavobacterium: A Hidden Helper for Improving Plant Health

“…Interestingly, the OMVs from aquatic Flavobacterium species contain diverse molecules that can modulate host immunity including small RNA, mRNA, various enzymes, antigenic proteins, and oligosaccharides (Chapagain et al, 2021(Chapagain et al, , 2023Møller et al, 2005). In addition, OMVs have been observed in some Flavobacterium strains with PGP activity (Jung et al, 2021); however, little is known about the role of these OMVs in interactions with plants. Further study is needed to investigate if OMVs of plant-associated Flavobacterium species may play an essential role in beneficial interactions with plants.…”

“…2 ). For example, all 32 Flavobacterium strains, isolated from tomato rhizosphere soil, including F. anhuiense , F. aquidurense , F. beibuense , F. daejeonense , and F. dauae , showed plant growth promotion (PGP) activity in tomato plants ( Jung et al, 2021 ; Kwak et al, 2018 ). Similarly, Flavobacterium sp.…”

“…Numerous bacteria including the Flavobacterium species can produce small (40–200 nm in diameter) spherical particles derived from the outer membrane called outer membrane vesicles (OMVs) ( Jung et al, 2021 ; McMillan et al, 2021 ; Møller et al, 2005 ). Among Flavobacterium species such as F. psychrophilum , F. johnsoniae , and F. columnare , OMVs have been intensively investigated in aquatic conditions ( Arias et al, 2012 ; Møller et al, 2005 ; Sato et al, 2021 ).…”