Rhizobium pusense sp. nov., isolated from the rhizosphere of chickpea (Cicer arietinum L.)

A novel bacterial strain, designated NRCPB10T, was isolated from rhizosphere soil of chickpea (Cicer arietinum L.) in Pusa, New Delhi, India. The 16S rRNA gene sequence of strain NRCPB10T showed highest similarity (98.9 %) to that of Rhizobium radiobacter NCPPB 2437T, followed by Rhizobium larrymoorei AF3-10T (97.7 %) and Rhizobium rubi IFO 13261T (97.4 %). Phylogenetic analysis of strain NRCPB10T based on the housekeeping genes recA and atpD confirmed its position as distinct from recognized Rhizobium species. Levels of DNA–DNA relatedness between strain NRCPB10T and R. radiobacter ICMP 5785T, R. larrymoorei LMG 21410T and R. rubi ICMP 6428T were 51.0, 32.6 and 27.3 %, respectively. Cellular fatty acids of strain NRCPB10T were C18 : 1ω7c (58.9 %), C16 : 0 (15.5 %), C19 : 0 cyclo ω8c (11.5 %), iso-C16 : 1 (5.8 %), C16 : 0 3-OH (4.5 %), C16 : 1ω7c (2.1 %) and C18 : 0 (1.3 %). The G+C content of the genomic DNA of strain NRCPB10T was 59.0 mol%. Strain NRCPB10T did not nodulate chickpea plants or induce tumours in tobacco plants. Phenotypic and physiological properties along with SDS-PAGE of whole-cell soluble proteins differentiated strain NRCPB10T from its closest phylogenetic neighbours. On the basis of data from the present polyphasic taxonomic study, strain NRCPB10T is considered to represent a novel species of the genus Rhizobium, for which the name Rhizobium pusense sp. nov. is proposed. The type strain is NRCPB10T ( = LMG 25623T = JCM 16209T = NCIMB 14639T).