Microbacterium rhizosphaerae sp. nov., isolated from a Ginseng field, South Korea

A novel Gram-stain positive, aerobic, short rod-shaped, non-motile bacterium, designated strain CHO1T, was isolated from rhizosphere soil from a ginseng agriculture field. Strain CHO1T was observed to form yellow colonies on R2A agar medium. The cell wall peptidoglycan was found to contain alanine, glycine, glutamic acid, d-ornithine and serine. The cell wall sugars were identified as galactose, mannose, rhamnose and ribose. Strain CHO1T was found to contain MK-11, MK-12, MK-13 as the predominant menaquinones and anteiso-C15:0, iso-C16:0, and anteiso-C17:0 as the major fatty acids. Diphosphatidylglycerol, phosphatidylglycerol, phosphoglycolipid, an unidentified phospholipid and three unidentified glycolipids were found to be present in strain CHO1T. Based on 16S rRNA gene sequence analysis, strain CHO1T was found to be closely related to Microbacterium mangrovi DSM 28240T (97.81 % similarity), Microbacterium immunditiarum JCM 14034T (97.45 %), Microbacterium oryzae JCM 16837T (97.33 %) and Microbacterium ulmi KCTC 19363T (97.10 %) and to other species of the genus Microbacterium. The DNA G+C content of CHO1T was determined to be 70.1 mol %. The DNA–DNA hybridization values of CHO1T with M. mangrovi DSM 28240T, M. immunditiarum JCM 14034T, M. oryzae JCM 16837T and M. ulmi KCTC 19363T were 46.7 ± 2, 32.4 ± 2, 32.0 ± 2 and 29.2 ± 2 %, respectively. On the basis of genotypic, phenotypic and phylogenetic properties, it is concluded that strain CHO1T represents a novel species within the genus Microbacterium, for which the name Microbacterium rhizosphaerae sp. nov. is proposed. The type strain of M. rhizosphaerae is CHO1T (= KEMB 7306-513T = JCM 31396T).