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 degrees C (optimum 37 degrees 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% (SD52.19). DNA-DNA hybridization with P. pelagia CL-AP6T, P. xinjiangensis S3-3T 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 : 1 omega 7c and/or C18 : (1)omega 6c) 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) (5JCM 19138(T) 5CCTCC AB 2013069(T) 5NRRL B-59988(T)).