Okibacterium endophyticum sp. nov., a novel endophytic actinobacterium isolated from roots of Salsola affinis C. A. Mey.

A white bacterial strain, designated EGI 650022(T), was isolated from the roots of Salsola affinis C. A. Mey, collected from Urumqi City, Xinjiang, north-western China. The strain was found to be aerobic, Gram-stain positive, oxidase-positive and catalase-positive. Cells were non-motile and irregular rods. Growth occurred at NaCl concentrations between 0 and 7 % (w/v), temperatures between 5 and 45 °C, and pH 6.0-9.0. Phylogenetic analysis based on 16S rRNA gene sequence indicated that strain EGI 650022(T) belongs to a clade with the genera Okibacterium and Plantibacter in the family Microbacteriaceae. The novel strain EGI 650022(T) showed highest levels of 16S rRNA gene sequence similarity with members of the genera Okibacterium and Plantibacter (97.2-98.0 %). The cell-wall peptidoglycan contained glutamate, homoserine, glycine, alanine and lysine. The predominant menaquinones (MKs) were MK-11, MK-12 and MK-12 (H4). The polar lipid pattern comprised phosphatidylglycerol, diphosphatidylglycerol, two unknown glycolipids and two unknown phospholipids. The major fatty acids were anteiso-C15:0 and anteiso-C17:0. The DNA G+C content was 66.0 mol%. The DNA-DNA relatedness values of strain EGI 650022(T) with Okibacterium fritillariae DSM 12584(T), Plantibacter flavus DSM 14012(T) and Plantibacter auratus DSM 19586(T) were 39.7, 19.7 and 22.0 %. Based on phylogenetic, phenotypic, chemotaxonomic and DNA-DNA hybridization data, strain EGI 650022(T) is considered to represent a novel species of the genus Okibacterium, for which the name Okibacterium endophyticum sp. nov. is proposed; the type strain is EGI 650022(T) (=JCM 30086(T) = KCTC 29492(T)).