Isolation, Characterization and Phylogenetic Analysis of Nodule-Associated Bacteria from Mimosa Pudica L.

Abstract

The interaction between rhizobia and other nodule-associated bacteria assists to mitigate nutrient stress in leguminous plants by fixing atmospheric nitrogen and synthesizing plant growth regulators. The beneficial effects of microbial inoculants emphasize the need for further research and their use in modern agriculture. The present study describes the isolation, molecular identification, characterization, and phylogenetic analysis of noduleassociated bacteria from Mimosa pudica Linnaeus. Isolation and phenotypic characterization of nodule-associated bacteria were carried out according to standard procedures. Molecular characterization of the isolates was performed using 16S ribosomal RNA. Plant growth promoting the ability of selected isolates was analyzed by assessing indole acetic acid production, nitrogenfixing ability and organic acid production. Evolutionary distance and relatedness were analyzed using the neighbor-joining method. Thirteen nodule-associated bacteria were isolated and identified using 16S rRNA gene sequencing. The selected isolates such as Rhizobium sp. CU8 and three other co-resident non-rhizobial nodule-associated bacteria (Bacillus cereus MY5, Ralstonia pickettii MY1 and Lactococcus lactis MY3) exhibited plant growth promotion and other potential microbial activities. Phylogenetic analysis revealed the genetic relatedness and evolutionary significance of all the thirteen isolates reside in the root nodule of M. pudica. The present study identified four isolates with plant growth promoting properties. L. lactis MY3 is the first report as a co-resident plant growth promoter from the root nodules of M. pudica.