Phyllobacterium sophorae sp. nov., a symbiotic bacterium isolated from root nodules of Sophora flavescens.

Abstract

Two novel Gram-stain-negative strains (CCBAU 03422(T) and CCBAU 03415) isolated from root nodules of Sophora flavescens were classified phylogenetically into the genus Phyllobacterium based on the comparative analysis of 16S rRNA and atpD genes. They showed 99.8 % rRNA gene sequence similarities to Phyllobacterium brassicacearum LMG 22836(T), and strain CCBAU 03422(T) showed 91.2 and 88.6 % atpD gene sequence similarities to strains Phyllobacterium endophyticum LMG 26470(T) and Phyllobacterium brassicacearum LMG 22836(T), respectively. Strain CCBAU 03422(T) contained Q-10 as its major quinone and showed a cellular fatty acid profile, carbon source utilization and other phenotypic characteristics differing from type strains of related species. DNA-DNA relatedness (lower than 48.8 %) further confirmed the differences between the novel strains and the type strains of related species. Strain CCBAU 03422(T) could nodulate and fix nitrogen effectively on its original host plant, Sophora flavescens. Based upon the results mentioned above, a novel species named Phyllobacterium sophorae is proposed and the type strain is CCBAU 03422(T) ( = A-6-3(T) = LMG 27899(T) = HAMBI 3508(T)).