Adhaeribacter rhizoryzae sp. nov., a fibrillar matrix-producing bacterium isolated from the rhizosphere of rice plant

Abstract

A novel fibrillar matrix-producing, rod-shaped, red-orange, asporogenous, aerobic bacterium, designated DK36(T), was isolated from roots of a rice plant in the Ilsan region near Dongguk University, South Korea. Cells of strain DK36T were Gram-stain-negative and motile by means of gliding. The temperature and pH ranges for growth were 7-35 degrees C (optimum: 30 degrees C) and pH 5-10 (optimum: pH 7.0). The strain did not require NaCl for growth but tolerated up to 8 % (w/v) NaCl. Phylogenetic anlaysis of the 16S rRNA gene sequence revealed that DK36(T) formed a monophyletic clade with Adhaeribacter aerophilus 6425 S-25(T), Adhaeribacter aerolatus 6515 J-31(T) and Adhaeribacter swui 17mud1-7(T) with sequence similarities of 96.3, 95.5 and 95.2%, respectively. The average nucleotide identity and in silico DNA-DNA hybridization values of strain DK36(T) with the most closely related strains whose whole genomes are publicly available were 72.5-83.6% and 19-28 %, respectively. The strain showed the typical chemotaxonomic characteristics of the genus Adhaeribacter, with the presence of menaquinone MK-7 as the respiratory quinone, and C-16:1 omega 5c, iso-C-15:0 and summed feature 4 (composed of iso-C-17:1 I/anteiso-C-17:1 B) as the major fatty acids. The polar lipid profile consisted of phosphatidylethanolamine, one unidentified aminophosphoglycolipid, one unidentified phospholipid, two unidentified aminolipids and five unidentified polar lipids. The genomic DNA G+C content based on the draft genome sequence was 43.4 mol%. The results of physiological and biochemical tests and 16S rRNA gene sequence analysis clearly revealed that strain DK36(T) represents a novel species of the genus Adhaeribacter, for which the name Adhaeribacter rhizoryzae sp. nov. is proposed. The type strain is DK36(T) (=KACC 19902(T)=NBRC 113689(T)).