Rhizobium vallis sp. nov., isolated from nodules of three leguminous species

Abstract

Four bacterial strains isolated from root nodules of Phaseolus vulgaris , Mimosa pudica and Indigofera spicata plants grown in the Yunnan province of China were identified as a lineage within the genus Rhizobium according to the analysis of 16S rRNA gene sequences, sharing most similarity with Rhizobium lusitanum P1-7 T (99.1 % sequence similarity) and Rhizobium rhizogenes IAM 13570 T (99.0 %). These strains also formed a distinctive group from the reference strains for defined species of the genus Rhizobium in a polyphasic approach, including the phylogenetic analyses of the 16S rRNA gene and housekeeping genes ( recA, atpD, glnII ), DNA–DNA hybridization, BOX-PCR fingerprinting, phenotypic characterization, SDS-PAGE of whole-cell proteins, and cellular fatty acid profiles. All the data obtained in this study suggested that these strains represent a novel species of the genus Rhizobium , for which the name Rhizobium vallis sp. nov. is proposed. The DNA G+C content (mol%) of this species varied between 60.9 and 61.2 ( T m ). The type strain of R. vallis sp. nov. is CCBAU 65647 T ( = LMG 25295 T = HAMBI 3073 T ), which has a DNA G+C content of 60.9 mol% and forms effective nodules on Phaseolus vulgaris .