ISOLATION AND CHARACTERIZATION OF PLANT GROWTH-PROMOTING RHIZOBACTERIA FROM ORGANIC COMPOST AND BENEFICIAL EFFECT ON ORYZA SATIVA

Plant-growth-promoting rhizobacteria (PGPR) are beneficial bacteria in the rhizosphere that enhance plant growth. This study aimed to isolate and characterize PGPR for biofertilizer development. Sixteen bacterial strains were isolated from organic compost at the On Nut organic composting plant in Bangkok, Thailand. These isolates were evaluated for plant-growth-promoting (PGP) properties, such as phosphate solubilization and the production of indole-3-acetic acid (IAA), ammonia, and chitinase. Isolates 10, 12, 15, and 18 exhibited PGP properties, with the highest phosphate solubilization. In particular, isolate 12 demonstrated the production of IAA at 0.0478 μg/mL and of gibberellin (GA3) at 0.3193 μg/mL, solubility of phosphate at 11.0119 μg/mL, and the highest percent inhibition of radial growth (PIRG) against Colletotrichum gloeosporioides C1060. In pot experiments, rice (Oryza sativa L. cv. RD47) grown with isolate 12 for 10 days showed statistically significantly increased root dry weight (p ≤ 0.05) compared to the other treatments. 16S rRNA sequence analysis in EzBioCloud revealed that isolate 12 was closely related to Bacillus licheniformis. Therefore, this bacterium exhibits the potential for us as a biofertilizer for early-stage Oryza sativa L. cv. RD47.