Flavobacterium Pokkalii sp. nov., a Novel Plant Growth Promoting Native Rhizobacteria Isolated from Pokkali Rice Grown in Coastal Saline Affected Agricultural Regions of Southern India, Kerala

Abstract

Nine plant-associated bacterial strains designated as L1I52T , NRK F1, NRK F15, NRK F16, NRK F41, NRK F42, NRK F47, NRK F49, and NRK F50 originating from the roots and rhizosphere region of a coastal saline tolerant pokkali rice were taxonomically characterized in this study. Genomic fingerprinting using Enterobacterial Repetitive Intergenic Consensus (ERIC) primers discriminated the nine strains based on the DNA fingerprint patterns indicating that they were not clonal in origin. Phylogenetic analysis using 16S rRNA and other five housekeeping genes (gyrB, glyA, atpA, dnaK and murG) revealed that the novel strains constituted a single novel species within the genus Flavobacterium. In all tree construction methods, the novel strains formed a distinct phylogenetic branch, with Flavobacterium daejeonense GH1-10T , F. sufflavum BBQ-12T , and F. glycines Gm-149T as their nearest phylogenetic neighbours. However, average nucleotide identity (ANI), average amino acid identity (AAI) and digital DNA-DNA hybridization (dDDH) comparison between the draft genomes of L1I52T (representative isolate) and it’s nearest phylogenetic neighbours were well below the proposed threshold values (< 95 % and < 70 %) used for species discrimination. Thus, based on the phenotypic, genotypic and chemotaxonomic data obtained in this study, we describe a novel Flavobacterium species for which we propose the name Flavobacterium pokkalii sp.nov., with strain L1I52T (=MTCC 12454T =KCTC 42429T ) as the type strain. In addition, L1I52T is a potential plant growth promoting rhizobacteria as they can promote pokkali rice growth and we identified several plant associated gene features in the genome of L1I52T that are potentially involved in plant microbe interactions.