Sphingomonas quercus sp. nov., Isolated from Rhizosphere Soil of Quercus mongolica

Strain XMGL2 T , isolated from rhizosphere soil of Quercus mongolica in China, was characterized using a polyphasic taxonomic approach. Cells were Gram-negative, aerobic, non-spore-forming, and rod-shaped. Growth occurred at 20–37 °C (optimum, 28 °C), pH 5.0–10.0 (optimum, pH 6.0), and with 0–1% NaCl (optimum, 1%). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain XMGL2 T was related to members of the genus Sphingomonas and had the highest 16S rRNA gene sequence identity to Sphingomonas oleivorans FW-11 T (96.4%). The average nucleotide identity and digital DNA–DNA hybridization values between strain XMGL2 T and the closely related taxa Sphingomonas oleivorans FW-11 T and Sphingomonas fennica K101 T were 75.3/19.8% and 75.8/20.2%, respectively. The major cellular fatty acids were C 18:1 ω 7 c , C 14:0 2-OH, and C 16:0 . The major isoprenoid quinone was Q-10 and the polar lipid profile contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidyldimethylethanolamine, phosphatidylmonomethylethanolamine, an unidentified glycophospholipid and an unidentified phospholipid. The genomic DNA G + C content was 67.9%. Based on the phenotypic and genotypic properties and phylogenetic inference, strain XMGL2 T represents a novel species of the genus Sphingomonas , for which the name Sphingomonas quercus sp. nov. is proposed. The type strain is XMGL2 T (= JCM 34441 T = GDMCC 1.2153 T ).