Karakterisasi Rizobakteria Pemacu Tumbuh Tanaman dan Toleran Kekeringan

Abstract

Plant Growth Promoting Rhizobacteria (PGPR) are a group of bacteria that have some ability to support plant growth. Two of those rhizobacteria are Bacillus and Pseudomonas. This study aimed to isolate and characterize indigenous rhizobacteria Bacillus and Pseudomonas isolated from soybean (Glycine max) rhizosphere from Nusa Tenggara Barat. Characterization included the ability to stimulate soybean sprouts growth, indole acetic acid (IAA) production, the ability to face drought stress, phosphate solubilizing ability, and chitinase enzyme production. There were 22 isolates of Pseudomonas and 29 of Bacillus were isolated using selective media King's B and NB. Sixteen isolates consisting seven Pseudomonas and nine Bacillus isolates could significantly stimulate soybean sprouts growth. With the addition of 0.2 mM tryptophan in liquid media, bacteria are able to produce IAA in the concentration range of 1.02 to 21.06 ppm for genus Pseudomonas and 4.59 to 5.44 ppm for genus Bacillus. The sixteen isolates were tested for their ability in facing drought stress, phosphate solubilizing, and chitinase enzymes production. Isolates pntb80 and bntb20 can survive up to -2.5 MPa osmotic pressure on the media with PEG 6000 added as osmotic pressure controller. The highest phosphate solubilizing index were shown by pntb18 on Pikovskaya agar with tricalcium phosphate. The highest chitinolytic index were shown by bntb22 on 1% chitin media.