Mesorhizoblum shangrilense sp nov., isolated from root nodules of Caragana species

Five strains of bacteria isolated from nodules of Caragana bicolor and Caragana erinacea in Yunnan Province of China were classified within the genus Mesorhizobium in the class Alphaproteobacteria. The highest degree of 16S rRNA gene sequence similarity was determined to be to Mesorhizobium loti LMG 6125(T) (99.7%) and Mesorhizobium ciceri UPM-Ca7(T) (99.7%). Polyphasic taxonomic methods including SDS-PAGE of whole-cell soluble proteins, comparative housekeeping sequence analysis of atpD, glnII and recA, fatty acid profiles and a series of phenotypic and physiological tests allowed us to cluster the five strains into a coherent group while differentiating them from all previously established Mesorhizobium species. The DNA-DNA relatedness between the representative strain CCBAU 65327(T) and the type strains of M. loti and M. ciceri was 26.5 and 23.4%, respectively, clearly indicating that strain CCBAU 65327(T) represents a novel species for which we propose the name Mesorhizobium shangrilense sp. nov. Strain CCBAU 65327(T) (=LMG 24762(T) =HAMBI 3050(T)) is designated as the type strain, and could nodulate Caragana microphylla, Caragana intermedia, Glycyrrhiza uralensis, Astragalus adsurgens, Vigna unguiculata, Vigna radiata and Phaseolus vulgaris in cross-nodulation tests.