Rhizobium puerariae sp. nov., an endophytic bacterium from the root nodules of the medicinal plant Pueraria candollei var. candollei

A Gram-stain-negative, rod-shaped, motile bacterium, PC004 T , was isolated from root nodules of the Thai medicinal plan Pueraria candollei var. candollei . 16S rRNA gene sequence analysis indicated that the strain is phylogenetically related to species in the genus Rhizobium, showing highest similarity (96.6 %) with Rhizobium mesosinicum HAMBI 3194 T . The phylogenetic tree reconstructed based on 16S rRNA gene sequences showed that strain PC004 T forms a cluster with Rhizobium petrolearium KCTC 23288 T . Based on atpD , gyrB and recA gene sequences, strain PC004 T also showed low similarity ( < 90 %) to reference strains. These phylogenetic data indicate that PC004 T may represent a novel species. Strain PC004 T also exhibited low DNA-DNA relatedness with R. mesosinicum HAMBI 3194 T (8.2 %) and R. petrolearium KCTC 23288 T (26.3 %). The DNA G+C content of strain PC004 T was 64 mol%, which is within the range reported for the genus Rhizobium . The major fatty acid of PC004 T was C 18 : 1 ω7 c with minor amounts of C 16 : 0 , C 16 : 0 3-OH, C 18 : 0 3-OH, C 18 : 1 2-OH, C 19 : 0 cyclo ω8 c and summed feature 2. The strain was able to grow at pH 12 and with up to 2 % (w/v) NaCl. Strain PC004 T did not nodulate five tested legumes and the nifH and nodC genes were not detected by PCR. Based on the physiological, chemotaxonomic and phenotypic data from this study, strain PC004 T represents a novel species of the genus Rhizobium , for which the name Rhizobium puerariae sp. nov. is proposed; the type strain is PC004 T ( = BCC 73740 T  = NBRC 110722 T ).