Isoptericola rhizophila sp. nov., a novel actinobacterium isolated from rhizosphere soil

A Gram-positive, yellow pigmented strain, BKS 3-46(T) was isolated from a soil sample collected from the rhizosphere of Ficus benghalensis (banyan tree) in Bhitarkanika mangrove forest, in the Indian state of Odisha, and subjected to polyphasic taxonomic study. The 16S rRNA gene sequence of the strain was determined and the sequence analysis showed that strain BKS 3-46(T) should be assigned to the genus Isoptericola. The chemotaxonomic data supported this taxonomic placement i.e. presence of menaquinone MK-9(H4); major fatty acids anteiso C15:0 and iso-C15:0; and phosphatidylglycerol, diphosphatidylglycerol and phosphatidylinositol (PI) as major polar lipids. Further phylogenetic analysis of the 16S rRNA gene sequence confirmed that the strain BKS 3-46(T) belongs to the genus Isoptericola and is closely related to Isoptericola halotolerans MTCC 11265(T) (98.6 %) followed by Isoptericola nanjingensis MTCC 11633(T) (98.4 %) and Isoptericola chiayiensis MTCC 11634(T) (98.1 %). However, the DNA-DNA hybridization values obtained between strain BKS 3-46(T) and other related strains were well below the threshold that is required for the proposal of a novel species. The G+C content of the genomic DNA was determined to be 70.4 mol%. The phenotypic and genotypic data showed that the strain BKS 3-46(T) merits the recognition as a representative of a novel species of the genus Isoptericola. It is proposed that the isolate should be classified in the genus Isoptericola as a novel species, Isoptericola rhizophila sp. nov. The type strain is BKS 3-46(T) (=MTCC 11080(T)=JCM 19252(T)).