Arthrobacter endophyticus sp. nov., an endophytic actinobacterium isolated from root of Salsola affinis C. A. Mey.

A Gram-staining-positive, white-coloured, aerobic, non-motile, catalase-positive and oxidase-negative, endophytic actinobacterium, designated strain EGI 6500322T, was isolated from the surface-sterilized root of the halophyte Salsola affinis C. A. Mey collected from Urumqi, Xinjiang province, north-west China. Growth occurred at 5–35 °C (optimum 25–30 °C), at pH 5–10 (optimum pH 7–8) and with 0–13 % NaCl (w/v) (optimum 0–5 %). The predominant menaquinone was MK-9 (93.1 %). The major cellular fatty acids were anteiso-C15:0 (49.5 %) and iso-C15:0 (15.1 %). The cell-wall peptidoglycan contained lysine, alanine and glutamic acid. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, two unknown phospholipids and one unknown glycolipid. The DNA G+C content of strain EGI 6500322T was 62.0 mol%. Based on 16S rRNA gene sequence analysis, the nearest phylogenetic neighbours of strain EGI 6500322T were identified as Arthrobacter ardleyensis DSM 17432T (98.38 %) and Arthrobacter bergerei DSM 16367T (98.37 %). The DNA–DNA relatedness between strain EGI 6500322T and Arthrobacter ardleyensis DSM 17432T and Arthrobacter bergerei DSM 16367T was 53.4 ± 4.1 % and 30.5 ± 1.7 %, respectively. On the basis of the phylogenetic analysis, chemotaxonomic data, physiological characteristics and DNA–DNA hybridization data, strain EGI 6500322T should represent a novel species of the genus Arthrobacter, for which the name Arthrobacter endophyticus sp. nov. is proposed. The type strain is EGI 6500322T ( = KCTC 29490T = JCM 30091T).