Rhizobium Pakistanensis Sp. Nov., Isolated from Groundnut ( Arachis Hypogaea ) Nodules Grown in Rainfed Pothwar, Pakistan

A Gram-negative, white, non-motile, rod shaped bacterial strain BN-19T was isolated from a root nodule of groundnut (Arachis hypogaea) in Pakistan. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain BN-19T formed a subclade in the genus Rhizobium together with Rhizobium alkalisoli CCBAU 01393T, Rhizobium vignae CCBAU 05176T, Rhizobium huautlense SO2T and Rhizobium tarimense PL-41T with sequence similarities of 97.5, 97.3, 97.2 and 97.1 % respectively. Sequence analysis of housekeeping genes atpD, glnII and recA (with sequence similarities of ≤92 %) confirmed the unique position of BN-19T in the genus Rhizobium. DNA–DNA relatedness between the strain BN-19T and R. alkalisoli CCBAU 01393T, R. vignae CCBAU 05176T, R. huautlense SO2T and R. tarimense PL-41T were 20.6, 22.5, 15.9 and 20.5 % respectively, further confirming that BN-19T represents a novel species in the genus Rhizobium. The DNA G + C content was 60.1 mol%. The dominant fatty acids of strain BN-19T were C19:0 cyclo ω8c, summed feature 2 (C14:0 3OH and/or C16:1 iso I) and summed feature 8 (C18:1 ω7c). Some phenotypic features also differentiate the strain BN-19T from the related species. On the basis of these results, strain BN-19T is considered to represent a novel species in the genus Rhizobium, for which the name Rhizobium pakistanensis sp. nov. is proposed. The type strain is BN-19T (=LMG 27895T = CCBAU 101086T).