Novosphingobium pokkalii sp nov, a novel rhizosphere-associated bacterium with plant beneficial properties isolated from saline-tolerant pokkali rice.

Pokkali rice varieties are known for their saline tolerance when specifically grown in coastal saline affected agri-fields of southern Kerala. These fields are prone to seawater intrusion. During characterization of phytobeneficial rhizobacteria from this pokkali rice, L3E4T was isolated. This strain showed some plant growth-promoting functions (production of indole acetic acid (IAA), acetoin, and siderophore), biofilm formation and capacity to use a wide range of plant-derived organic compounds. In planta assay under axenic conditions showed a positive effect of L3E4T on pokkali rice growth; importantly, it was able to attach and colonize pokkali rice roots in the presence of natural seawater, a key adaptation required for survival in pokkali rice fields. Phylogenetic analysis using 16S rRNA, recA, and gyrB gene sequences showed that strain L3E4T belongs to the genus Novosphingobium, with Novosphingobium capsulatum GIFU 11526T and Novosphingobium rhizosphaerae JM.1T being the nearest phylogenetic relatives. In addition, DNA-DNA hybridization analysis and phenotypic traits established that this strain belongs to a novel Novosphingobium species, for which we propose the name Novosphingobium pokkalii sp. nov. The type strain is represented by strain L3E4T (=MTCC 12357T = KCTC 42224T).