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 ω7c, 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).