Isolation and Screening of Rhizosphere Bacteria from Sugarcane Roots for Plant Growth Promoting Traits: IAA Production and Phosphate Solubilization

This study aimed to isolate, characterize, and identify indole-3-acetic acid (IAA)-producing bacteria from the sugarcane (Saccharum officinarum) rhizosphere, as bacterial IAA is a key trait that facilitates plant growth promotion. The level of auxin production was characterized by calorimetric estimation of IAA and the ability to solubilized calcium phosphate was evaluated by a qualitative analysis of phosphate solubilization in NBRIP Agar assay. Bacterial strains designated A, B, C, D, E, H, J, L, M, N, O, R, and S were isolated from the rhizosphere soil of sugarcane and were pure cultured. These strains produced IAA at detectable levels and out of these strain "C" produced the maximum amount of IAA per gram of the bacterial cell pellet, i.e. 2.72 mg of IAA per gram of dry cell pellet. Bacterial strains A, D, M, E, J, R, O and N had the capacity of solubilize the insoluble calcium phosphate in NBRIP agar. 3 strains - M, N, and R were capable producing both plant growth promoting traits. This study concludes that bacterial strains capable of IAA production, phosphate solubilization, or—most promisingly—both functions, show significant potential as effective bio- inoculants and optimal components for plant growth-promoting biofertilizer consortia."