ABSTRACT
A novel bacterial strain, designated NRCPB10(T), was isolated from rhizosphere soil of chickpea (Cicer arietinum L.) in Pusa, New Delhi, India. The 16S rRNA gene sequence of strain NRCPB10(T) showed highest similarity (98.9 %) to that of Rhizobium radiobacter NCPPB 2437(T), followed by Rhizobium larrymoorei AF3-10(T) (97.7 %) and Rhizobium rubi IFO 13261(T) (97.4 %). Phylogenetic analysis of strain NRCPB10(T) based on the housekeeping genes recA and atpD confirmed its position as distinct from recognized Rhizobium species. Levels of DNA-DNA relatedness between strain NRCPB10(T) and R. radiobacter ICMP 5785(T), R. larrymoorei LMG 21410(T) and R. rubi ICMP 6428(T) were 51.0, 32.6 and 27.3 %, respectively. Cellular fatty acids of strain NRCPB10(T) were C(18 : 1)ω7c (58.9 %), C(16 : 0) (15.5 %), C(19 : 0) cyclo ω8c (11.5 %), iso-C(16 : 1) (5.8 %), C(16 : 0) 3-OH (4.5 %), C(16 : 1)ω7c (2.1 %) and C(18 : 0) (1.3 %). The G+C content of the genomic DNA of strain NRCPB10(T) was 59.0 mol%. Strain NRCPB10(T) 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 NRCPB10(T) from its closest phylogenetic neighbours. On the basis of data from the present polyphasic taxonomic study, strain NRCPB10(T) 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 NRCPB10(T) ( = LMG 25623(T) = JCM 16209(T) = NCIMB 14639(T)).
Subject(s)
Cicer/microbiology , Rhizobium/classification , Rhizobium/isolation & purification , Rhizosphere , Soil Microbiology , Base Composition , DNA, Bacterial/genetics , Fatty Acids/metabolism , India , Molecular Sequence Data , Phylogeny , RNA, Ribosomal, 16S/genetics , Rhizobium/genetics , Rhizobium/metabolismABSTRACT
A moderately thermophilic bacterial strain (HT4(T)) isolated from a hot spring sediment was characterized phenotypically and phylogenetically. Cells were Gram-negative, aerobic, non-sporulating, rod-shaped and motile by means of a single polar flagellum. Both oxidase and catalase activities were positive. Heterotrophic growth was observed at pH 6.0-8.5 and at 20-50 degrees C; optimum growth occurred at pH 7.5-8.0 and 37-42 degrees C. The major cellular fatty acids were C( 14 : 0) 3-OH, C(18 : 0) 3-OH, C( 18 : 1) 2-OH, C(18 : 1)omega 7c and C(19 : 0) cyclo omega8 c. The DNA G+C content of strain HT4(T) was 67.8 mol%. 16S rRNA gene sequence analysis indicated that strain HT4(T) clustered within the radiation of the genus Chelatococcus and showed 99.0 % similarity with Chelatococcus daeguensis CCUG 54519(T) and 96 % similarity with Chelatococcus asaccharovorans DSM 6462(T). However, levels of DNA-DNA relatedness between strain HT4(T) and Chelatococcus daeguensis CCUG 54519(T) and Chelatococcus asaccharovorans DSM 6462(T) were 52 and 20%, respectively. On the basis of the phenotypic, physiological and chemotaxonomic data, 16S rRNA gene sequence analysis and DNA-DNA hybridization results, strain HT4(T) is considered to represent a novel species of the genus Chelatococcus, for which the name Chelatococcus sambhunathii sp. nov. is proposed. The type strain is HT4(T) (=DSM 18167(T)=JCM 14988(T)).
