Arthrobacter zhaoxinii sp. nov. and Arthrobacter jinronghuae sp. nov., isolated from Marmota himalayana

Four yellow-coloured strains (zg-Y815^T/zg-Y108 and zg-Y859^T/zg-Y826) were isolated from the intestinal contents of Marmota himalayana and assigned to the ' Arthrobacter citreus group'. The four strains grew optimally on brain heart infusion agar with 5 % defibrinated sheep blood plate at 30 °C, pH 7.0 and with 0.5 % NaCl (w/v). Comparative analysis of their 16S rRNA genes indicated that the two strain pairs belong to the genus Arthrobacter , showing the highest similarity to Arthrobacter yangruifuii 785^T (99.52 %), which was further confirmed by the 16S rRNA gene and genome-based phylogenetic analysis. The comparative genomic analysis [digital DNA–DNA hybridization, (dDDH) and average nucleotide identity (ANI)] proved that the four strains are two different species (zg-Y815^T/zg-Y108, 71.7 %/96.8 %; zg-Y859^T/zg-Y826, 87.3 %/98.5 %) and differ from other known species within the genus Arthrobacter (zg-Y815^T, 19.6–32.3 %/77.2–88.0 %; zg-Y859^T, 19.5–29.3 %/77.4–86.3 %). Strain pairs zg-Y815^T/zg-Y108 and zg-Y859^T/zg-Y826 had the same major cellular fatty acids (iso-C_{16 : 0} and anteiso-C_{15 : 0}), with MK-8(H₂) as their dominant respiratory quinone (70.6 and 61.7 %, respectively). The leading polar lipids were diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylinositol. The detected amino acids and cell-wall sugars of the two new species were identical (amino acids: alanine, glutamic acid, and lysine; sugars: rhamnose, galactose, mannose, glucose, and ribose). According to the phylogenetic, phenotypic, and chemotaxonomic analyses, we concluded that the four new strains represented two different novel species in the genus Arthrobacter , for which the names Arthrobacter zhaoxinii sp. nov. (zg-Y815^T= GDMCC 1.3494^T = JCM 35821^T) and Arthrobacter jinronghuae sp. nov. (zg-Y859^T = GDMCC 1.3493^T = JCM 35822^T) are proposed.