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

A Gram-stain negative, aerobic, non-motile, short-rod-shaped bacterium, designated KBL-4-9T, was isolated from the storage liquid in the stems of Populus euphratica trees in Xinjiang, PR China. Strain KBL-4-9T 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-4-9T belonged to the genus Pseudomonas and showed the highest 16S rRNA gene sequence similarity of 97.36 % to Pseudomonas pelagia CL-AP6T, followed by Pseudomonas xinjiangensis S3-3T (97.16 %), Pseudomonas sabulinigri J64T (97.15 %) and Pseudomonas xiamenensis C10-2T (96.47 %). Analysis of strain KBL-4-9T 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-AP6T, P. xinjiangensis S3-3T and P. sabulinigri J64T revealed 49.3 % (sd = 3.04), 41.2 % and 52.5 % (sd = 4.45) relatedness, respectively. The major cellular fatty acids of strain KBL-4-9T were C16 : 0, C12 : 0, summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C17 : 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-4-9T 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-4-9T ( = JCM 19138T = CCTCC AB 2013069T = NRRL B-59988T).

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

An endophytic bacterium, designated K-38(T), was isolated from the storage liquid in the stems of Populus euphratica trees at the ancient Ugan River in Xinjiang, PR China. Strain K-38(T) was found to be rod-shaped, Gram-stain-negative, aerobic, non-motile and non-spore-forming. Strain K-38(T) grew at temperatures of 25-37 °C (optimum, 28 °C), at pH 6.0-9.0 (optimum, pH 7.5) and in the presence of 0-3 % (w/v) NaCl with 1 % as the optimum concentration for growth. According to phylogenetic analysis based on 16S rRNA gene sequences, strain K-38(T) was assigned to the genus Rhizobium with highest 16S rRNA gene sequence similarity of 97.2 % to Rhizobium rosettiformans W3(T), followed by Rhizobium nepotum 39/7(T) (96.5 %) and Rhizobium borbori DN316(T) (96.2 %). Phylogenetic analysis of strain K-38(T) based on the protein coding genes recA, atpD and nifH confirmed (similarities were less than 90 %) it to be a representative of a distinctly delineated species of the genus Rhizobium. The DNA G+C content was determined to be 63.5 mol%. DNA-DNA relatedness between K-38(T) and R. rosettiformans W3(T) was 48.4 %, indicating genetic separation of strain K-38(T) from the latter strain. The major components of the cellular fatty acids in strain K-38(T) were revealed to be summed feature 8 (comprising C18 : 1ω7c and/or C18 : 1ω6c; 57.2 %), C16 : 0 (13.6 %) and summed feature 2 (comprising C12 : 0 aldehyde, C14 : 0 3-OH/iso-C16 : 1 I and/or unknown ECL 10.928; 11.0 %). Polar lipids of strain K-38(T) include phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol, two unidentified aminophospholipids and two unidentified phospholipids. Q-10 was the major quinone in strain K-38(T). Based on phenotypic, chemotaxonomic and phylogenetic properties, strain K-38(T) represents a novel species of the genus Rhizobium, for which the name Rhizobium populi sp. nov. is proposed. The type strain is K-38(T) ( = CCTCC AB 2013068(T) = NRRL B-59990(T) = JCM 19159(T)).