Pseudomonas populi sp. nov., an endophytic bacterium isolated from Populus euphratica

A Gram-stain negative, aerobic, non-motile, short-rod-shaped bacterium, designated KBL-4-9^T, was isolated from the storage liquid in the stems of Populus euphratica trees in Xinjiang, PR China. Strain KBL-4-9^T grew at 4-45 °C (optimum 37 °C), 1-3 % (w/v) NaCl (optimum 1 %, w/v) and pH 5.5-9.5 (optimum pH 7.5). Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain KBL-4-9^T belonged to the genus Pseudomonas and showed the highest 16S rRNA gene sequence similarity of 97.36 % to Pseudomonas pelagia CL-AP6^T, followed by Pseudomonas xinjiangensis S3-3^T (97.16 %), Pseudomonas sabulinigri J64^T (97.15 %) and Pseudomonas xiamenensis C10-2^T (96.47 %). Analysis of strain KBL-4-9^T based on the three housekeeping genes, rpoB, rpoD and gyrB, further confirmed the phylogenetic assignment of the isolates. The DNA G+C content was 61.6 mol% (sd = 2.19). DNA-DNA hybridization with P. pelagia CL-AP6^T, P. xinjiangensis S3-3^T and P. sabulinigri J64^T revealed 49.3 % (sd = 3.04), 41.2 % and 52.5 % (sd = 4.45) relatedness, respectively. The major cellular fatty acids of strain KBL-4-9^T were C_16 : 0, C_12 : 0, summed feature 8 (C_18 : 1ω7c and/or C_18 : 1ω6c) and C_17 : 0 cyclo. The major isoprenoid quinone was Q-9. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and phosphatidylcholine. On the basis of phenotypic, chemotaxonomic and phylogenetic properties, strain KBL-4-9^T is considered to represents a novel species of the genus Pseudomonas, for which the name Pseudomonas populi sp. nov. is proposed. The type strain is KBL-4-9^T ( = JCM 19138^T = CCTCC AB 2013069^T = NRRL B-59988^T).