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

Abstract

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 <i>Populus euphratica</i> 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 <i>Pseudomonas</i> and showed the highest 16S rRNA gene sequence similarity of 97.36 % to <i>Pseudomonas pelagia</i> CL-AP6^T, followed by <i>Pseudomonas xinjiangensis</i> S3-3^T (97.16 %), <i>Pseudomonas sabulinigri</i> J64^T (97.15 %) and <i>Pseudomonas xiamenensis</i> C10-2^T (96.47 %). Analysis of strain KBL-4-9^T based on the three housekeeping genes, <i>rpoB</i>, <i>rpoD</i> and <i>gyrB</i>, further confirmed the phylogenetic assignment of the isolates. The DNA G+C content was 61.6 mol% (sd = 2.19). DNA-DNA hybridization with <i>P. pelagia</i> CL-AP6^T, <i>P. xinjiangensis</i> S3-3^T and <i>P. sabulinigri</i> 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}ω7<i>c</i> and/or C_{18 : 1}ω6<i>c</i>) 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 <i>Pseudomonas</i>, for which the name <i>Pseudomonas populi</i> sp. nov. is proposed. The type strain is KBL-4-9^T ( = JCM 19138^T = CCTCC AB 2013069^T = NRRL B-59988^T).