Rhizobium alkalisoli sp. nov., isolated from Caragana intermedia growing in saline-alkaline soils in the north of China.

Three rhizobial strains (CCBAU 01393(T), CCBAU 01389 and CCBAU 03239) isolated from nodules of Caragana intermedia grown in saline-alkaline soils in the north of China had identical 16S rRNA genes that showed 99.7 and 99.5 % sequence similarities with those of Rhizobium huautlense SO2(T) and Rhizobium galegae USDA 4128(T), respectively. Phylogenies of the housekeeping genes atpD, recA and glnII confirmed their distinct position, differing from recognized Rhizobium species. SDS-PAGE of whole-cell soluble proteins and a series of phenotypic and physiological tests allowed us to differentiate the novel group from all closely related recognized Rhizobium species. The levels of DNA-DNA relatedness between strain CCBAU 01393(T) and R. huautlense SO2(T) and R. galegae USDA 4128(T) were 34.9 and 20.5 %, respectively. Therefore, we propose that strains CCBAU 01393(T), CCBAU 01389 and CCBAU 03239 represent a novel species, Rhizobium alkalisoli sp. nov., with strain CCBAU 01393(T) (=LMG 24763(T)=HAMBI 3051(T)) as the type strain. This strain could form effective nodules on Caragana microphylla, Phaseolus vulgaris and Vigna radiata.