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

Strain XMGL2, 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 was related to members of the genus Sphingomonas and had the highest 16S rRNA gene sequence identity to Sphingomonas oleivorans FW-11 (96.4%). The average nucleotide identity and digital DNA-DNA hybridization values between strain XMGL2 and the closely related taxa Sphingomonas oleivorans FW-11 and Sphingomonas fennica K101 were 75.3/19.8% and 75.8/20.2%, respectively. The major cellular fatty acids were C ω7c, C 2-OH, and C. 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 represents a novel species of the genus Sphingomonas, for which the name Sphingomonas quercus sp. nov. is proposed. The type strain is XMGL2 (= JCM 34441 = GDMCC 1.2153).