Rhizobium tarimense sp. nov., isolated from soil in the ancient Khiyik River

Abstract

A Gram-negative, non-motile, pale-yellow, rod-shaped bacterial strain, PL-41T, was isolated from Populus euphratica forest soil at the ancient Khiyik River valley in Xinjiang Uyghur Autonomous Region, People's Republic of China. Strain PL-41T grew optimally at 30 °C and pH 7.0–8.0. The major quinone was Q-10. The predominant cellular fatty acids of strain PL-41T were summed feature 8 (comprising C18 : 1ω7c and C18 : 1ω6c), C16 : 0 and C19 : 0 cyclo ω8c. Polar lipids of strain PL-41T include two unidentified aminophospholipids (APL1, 2), two unidentified phospholipids (PL1, 2), phosphatidylcholine and three unidentified lipids (L1–3). Strain PL-41T showed 16S rRNA gene sequence similarity of 97.0–97.5 % to the type strains of recognized species of the genus Rhizobium . Phylogenetic analysis of strain PL-41T based on the sequences of housekeeping genes recA and atpD confirmed (similarities are less than 90 %) its position as a distinct species of the genus Rhizobium . The DNA G+C content was 57.8 mol%. DNA–DNA relatedness between strain PL-41T and the type strains of Rhizobium huautlense S02T, Rhizobium alkalisoli CCBAU 01393T, Rhizobium vignae CCBAU 05176T and Rhizobium loessense CCBAU 7190BT were 33.4, 22.6, 25.5 and 45.1 %, respectively, indicating that strain PL-41T was distinct from them genetically. Strain PL-41T also can be differentiated from these four phylogenetically related species of the genus Rhizobium by various phenotypic properties. On the basis of phenotypic properties, phylogenetic distinctiveness and genetic data, strain PL-41T is considered to represent a novel species of the genus Rhizobium , for which the name Rhizobium tarimense sp. nov. is proposed. The type strain is PL-41T ( = CCTCC AB 2011011T = NRRL B-59556T).