Genetic and Physiological Characterization of Soybean-Nodule-Derived Isolates from Bangladeshi Soils Revealed Diverse Array of Bacteria with Potential Bradyrhizobia for Biofertilizers.

Genetic and physiological characterization of bacteria derived from nodules of leguminous plants in the exploration of biofertilizer is of paramount importance from agricultural and environmental perspectives. Phylogenetic analysis of the 16S rRNA gene of 84 isolates derived from Bangladeshi soils revealed an unpredictably diverse array of nodule-forming and endosymbiotic bacteria-mostly belonging to the genus . A sequence analysis of the symbiotic genes ( and ) revealed similarities with the 16S rRNA gene tree, with few discrepancies. A phylogenetic analysis of the partial operon (16S-ITS-23S) and multi-locus sequence analysis of , , and identified that the isolates belonged to , , and species. In the pot experiment, several isolates showed better activity than USDA110, and the Bho-P2-B2-S1-51 isolate of showed significantly higher acetylene reduction activity in both cv. Enrei and Binasoybean-3 varieties and biomass production increased by 9% in the Binasoybean-3 variety. Tha-P2-B1-S1-68 isolate of significantly enhanced shoot length and induced 10% biomass production in Binasoybean-3. These isolates grew at 1-4% NaCl concentration and pH 4.5-10 and survived at 45 °C, making the isolates potential candidates for eco-friendly soybean biofertilizers in salty and tropical regions.