Screening Of Free-Living Indole Acetic Acid Producing Rhizobacteria From Shallot Rhizospheres In The Island Of Sulawesi

Auxin producing bacteria can be isolated from plant rhizospheres and used as inoculants for improving the growth and yield of agricultural crops. The present study focuses on the screening of indole-3-acetic acid producing rhizobacterial isolated from the rhizosphere soil of shallot plants \ngrown at five provinces in Sulawesi. A total of 125 bacterial isolates were screened and characterized for the production of bioauxin, Indole-3- Acetic Acid (IAA) by colorimeter method. The IAA activity was induced when the isolates were grown in the presence of L-Tryptophan, a physiological precursor of auxins. 51 out of 125 rhizobacterial isolates were found to produce IAA in the culture filtrates with amount ranged from 0.76 to 2.33 ppm, of these, five isolates (MG9, LB3, MK6-1-1, MK11, and GR25) were able to produce 2.05, 2.14, 2.20, 2.33, and 2.33 ppm of IAA respectively. Therefore, these five isolates are needed to be further studied due to their potential to be developed as plant growth promoting rhizobacteria in the field application.