Pararhizobium qamdonense sp. nov., Isolated from an Alpine Soil in Tibet and the Reclassification of Rhizobium gei Shi et al. 2016 as Pararhizobium gei comb. nov.

A novel Gram-stain-negative, aerobic, rod-shaped bacterium named T808 was isolated from an alpine soil in Qamdo, Tibet, PR China. Strain T808 grew at 5-30℃, pH 5.0-9.0 (optimum, 25℃ and pH 7.0-8.0) with 0-2% (w/v) NaCl (optimum, 0%). The 16S rRNA gene sequences of strain T808 showed the highest similarity with Pararhizobium herbae CCBAU83011 (98.8%), followed by Pararhizobium polonicum F5.1 (98.7%), Pararhizobium giardinii H152 (98.5%), Rhizobium gei ZFJT-2 (98.4%), and Pararhizobium antarcticum NAQVI59 (97.5%). The highest digital DNA-DNA hybridization (dDDH), core-proteome average amino acid identity (cpAAI) and average nucleotide identity (ANI) values between strain T808 and related strains were estimated as 28.0%, 92.1% and 84.4%, respectively. Phylogenetic analysis based on 16S rRNA, core-proteome and whole-genome indicated that strain T808 belonged to the genus Pararhizobium. The genome size was 6.24 Mbp with genomic DNA G + C content of 60.1%. The major cellular fatty acids were Summed feature 8 (C ω7c or C ω6c), C and C cyclo ω8c. The polar lipids were diphosphatidyl glycerol, phosphatidyl glycerol, phosphatidyl ethanolamine, phosphatidyl choline and unidentified aminophospholipid. The isoprenoid quinone were ubiquinone-10 and ubiquinone-9. Based on phenotypic, phylogenetic, and genotypic data, strain T808 is considered to represent a novel species of the genus Pararhizobium, for which the name Pararhizobium qamdonense sp. nov. is proposed. The type strain is T808 (= JCM 36247 = CICC 25216). According to phylogenetic coherence based on 16S rRNA, core-proteome and whole-genome, it is also proposed that the type strain Rhizobium gei Shi et al. 2016 should be reclassified as Pararhizobium gei comb. nov., the type strain is ZFJT-2 (= CCTCC AB 2013015 = KCTC 32301 = LMG 27603).