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

A Gram-negative, non-motile, pale-yellow, rod-shaped bacterial strain, PL-41(T), 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-41(T) 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-41(T) were summed feature 8 (comprising C18 : 1ω7c and C18 : 1ω6c), C16 : 0 and C19 : 0 cyclo ω8c. Polar lipids of strain PL-41(T) include two unidentified aminophospholipids (APL1, 2), two unidentified phospholipids (PL1, 2), phosphatidylcholine and three unidentified lipids (L1-3). Strain PL-41(T) 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-41(T) 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-41(T) and the type strains of Rhizobium huautlense S02(T), Rhizobium alkalisoli CCBAU 01393(T), Rhizobium vignae CCBAU 05176(T) and Rhizobium loessense CCBAU 7190B(T) were 33.4, 22.6, 25.5 and 45.1 %, respectively, indicating that strain PL-41(T) was distinct from them genetically. Strain PL-41(T) 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-41(T) 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-41(T) ( = CCTCC AB 2011011(T) = NRRL B-59556(T)).

[Phylogenetic diversity of culturable endophytic bacteria isolated from the Populus euphratica at the disused ancient Ugan river].

OBJECTIVE: The aim of this study was to identify the culturable endophytic bacteria recovered from the Populus euphratica at the disused (122 years ago) ancient Ugan river of middle reachs of Tarim river, and to understand their Phylogenetic diversity and community structure. METHODS: Bacteria were isolated from the storage liquid in the stem of 2 Populus euphratica stands by using 3 types of different cultural medium (Luria-Bertani, Trypticase Soy Agar and Nutrient Agar), followed carry out 16S rDNA identifications and analysis of their biodiversity. RESULTS: A total of 62 phenotypically different isolates were sequenced and according to their 16S rDNA sequence similarities to type strains of described organisms, they have been placed into four phylogenetic groups (1, Firmicutes; 2, Actinobacteria; 3, Alpha Proteobacteria and 4, Gamma Proteobacteria), 18 genera and 32 species. Among them, Bacillus and pseudomonas were the most widely distributed and predominant, occupied the majority of isolates 40.32% and 16.13%, respectively. Isolate KTH-63 (HM371419) formed a distinct clade with Macrococcus brunensis in phylogenetic tree based on 16S rDNA sequence among the family Staphylococcaceae, so it was demonstrated that the KTH-63 represents a potential novel genus and novel species within the family Staphylococcaceae with 92.491% sequence similarity with the described species Macrococcus brunensis of this family. Isolates KLH-1, KLH-21, KLH-18, KLH-25, KNA-3, KTH-8, KTH-14, KTH-20 and KNA-26 with 96.089% - 97.769% sequence similarities to their closely related members were presumed to be potential novel species, and the discovery rate of potential novel species in the endophytic bacterial community of Populus euphratica was reach up to 16.13%. Furthermore, 10 genera and 18 species have been added to the plant endophytic bacterial categoria by the data obtained in this work. CONCLUSION: The result showed that the cultivable endophytic bacterial diversity in Populus euphratica at Ugan river was very abundant and have high percentage of potential novel species, and it have greatly refreshed the plant endophytic bacterial records. The community structure obtained in this study also may be presumed as a miniature of the endophytic bacterial flora in the Populus euphratica during the recent ages before the affect of modern civilization prossessing to Tarim river valley, which deserve further study and exploitation.