Printed in Great Britain Characterization of bacteria isolated from wild legumes in the north-western regions of China

Nodule isolates from 11 species of wild legumes in north-western China were characterized by numerical taxonomy, PCR-based 165 rRNA gene RFLP and sequence analyses, DNA-DNA hybridization, restriction patterns of nodDA5 and nifH genes, and symbiotic propetties. Based on the results of numerical taxonomy, most of the 35 new isolates were grouped into five clusters (clusters 7, 9, 12, 14 and 15). Clusters 7 and 12 were identified as Mesorhizobium amorphae and Agrobacterium tumefaciens, respectively, based on their high DNA homologies with the reference strains for these species, their 165 rRNA gene analysis and their phenotypic features. Results of 16s rDNA PCR-RFLP analysis showed that cluster 9 belonged to Rhizobium. Clusters 14 and 15 were identified as Mesorhizobium based on their moderately slow-growing, acid-producing characters and the high similarity of their 165 rDNA PCR-RFLP patterns to those of Mesorhizobium species. These two clusters were genomic species distinct from all described species based on analysis of DNA relatedness within this genus. The isolates in cluster 12 (Agrobacteriu