Microbacterium hibisci sp. nov., isolated from rhizosphere of mugunghwa (Hibiscus syriacus L.)

A Gram-stain-positive, aerobic, non-motile, short-rod shaped actinobacterium, designated THG-T2.14T, was isolated from soil sampled from the rhizosphere of mugunghwa. Growth occurred at 10-40 °C (optimum 30 °C), at pH 5.0-10.0 (optimum 7.0) and at 0-7.0 % NaCl (optimum 3.0 %). Based on 16S rRNA gene sequence analysis, the nearest phylogenetic neighbours of strain THG-T2.14T were identified as Microbacterium yannicii DSM 23203T (98.8 %), Microbacterium trichothecenolyticum DSM 8608T (98.8 %), Microbacterium arthrosphaerae DSM 22421T (98.7 %) and Microbacterium jejuense KACC 17124T (98.4 %). The major fatty acids were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, one unidentified lipid, two unidentified phospholipids and two unidentified phosphoglycolipids. The menaquinones were MK-12, and MK-13. The major polyamine was spermidine. The peptidoglycan contained ornithine, alanine, glycine, homoserine and glutamic acid. The diagnostic diamino acid was ornithine. The acyl type of the muramic acid was glycolyl. The whole-cell sugars were rhamnose, ribose, galactose, arabinose, xylose and glucose. The DNA G+C content of strain THG-T2.14T was 71.2 mol%. The DNA-DNA relatedness between strain THG-T2.14T and its closest reference strains were significantly lower than the threshold value of 70 %. On the basis of the phylogenetic analysis, chemotaxonomic data, physiological characteristics and DNA-DNA hybridization data, strain THG-T2.14T represents a novel species of the genus Microbacterium, for which the name Microbacterium hibisci sp. nov. is proposed. The type strain is THG-T2.14T (=KACC 18931T=CCTCC AB 2016180T).