Pontibacter rhizosphera sp. nov., isolated from rhizosphere soil of an Indian medicinal plant Nerium indicum.

A gram-negative, motile, straight to curved rod shaped, pink pigmented bacterium was isolated from a soil sample collected from the rhizosphere of an Indian medicinal plant, Nerium indicum (Chuvanna arali) and subjected to a detailed polyphasic taxonomic study. The strain, designated as IMTB-1969(T), matched with most of the phenotypic and chemotaxonomic properties of the genus Pontibacter and represents a novel species. The major fatty acids of the strain were monounsaturated iso/anteiso branched C17 fatty acids (45.1%) and iso-C15:0 (16.5%). MK-7 was the predominant isoprenoid quinone. According to 16S rRNA gene sequence analysis, strain IMTB-1969(T) was indicated to belonged to the phylum Bacteroidetes and further phylogenetic analysis revealed that the strain IMTB-1969(T) belongs to the family Cytophagaceae and genus Pontibacter. The highest 16S rRNA gene sequence similarity was with Pontibacter korlensis CCTCC AB 206081(T) (97.2%) and lower sequence similarity was observed with other species in the genus Pontibacter (95.9-94.0%). DNA-DNA relatedness study of the strain IMTB-1969(T) confirmed that it represents a novel species. The G+C content of the genomic DNA was 52.2 (±0.5) mol%. The results of physiological and biochemical tests allowed the genotypic and phenotypic distinction of strain IMTB-1969(T) from its closest phylogenetic relatives. The strain IMTB-1969(T) should be classified as novel species of the genus Pontibacter, for which the name Pontibacter rhizosphera sp. nov. is proposed. The type strain is IMTB-1969(T) (=MTCC 10673(T) = DSM 24399(T)).