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.