Characterization of plant growth-promoting rhizobacteria associated with Sesbania cannabina (Retz.) Pers.in long An Province, Vietnam

This study investigated characteristics of plant growth-promotion (PGP) of rhizobacteria associated with Sesbania cannabina (Retz.) Pers. in the Tan Hung district of Long An province, Vietnam. The rhizobacteria were studied colony, cell morphology and assessed capabilities of nitrogen fixation, phosphate solubilization, indole-3-acetic acid (IAA) production and siderophore synthesis. Colorimetric assays were employed to quantify nitrogen fixation, phosphate solubilization, and IAA synthesis. The Chrome Azurol Sulfonate (CAS) assay was used to detect bacterial siderophore production. A total of twenty-four rhizobacteria were isolated, exhibiting predominantly opaque white, flat colonies with diverse shapes, margins, and diameters ranging from 1 to 4 mm, a balanced distribution of Gram-positive and Gram-negative bacteria with rod and coccus shapes, demonstrated significant plant growth-promoting capabilities. Notably, isolates DDS24 and DDS21 displayed the highest nitrogen fixation, DDS23 exhibited the highest phosphate solubilization and DDS07, DDS05, and DDS06 exhibited superior IAA production. Fifty percent isolates demonstrated siderophore production abilities. The identified Sesbania cannabina (Retz.) Pers. rhizobacteria show significant promise as biofertilizers, and require further studies on their application to sustainable agricultural practices.