This study was to produce highly efficient antagonists to control soil borne plant
pathogen Rhizoctonia solani in rice. Soil samples from different location in
natural ecosystem were collected and characterization for antagonistic efficiency
between isolated bacteria and R. solani were performed. Antagonistic test in dual
culture showed that isolates S3B11 and SW2B49 had the highest antagonistic
activities with the inhibition zone of 36.0 mm and 32.2 mm on potato dextrose
agar (PDA) medium respectively. These two isolates produced chitinase on M9
agar supplemented with colloidal chitin as the sole carbon source. The results
indicated that these two strains hydrolyzed colloidal chitin after 3–4 days. The
production of chitinase could be one of the factors which suppressed growth of
R. solani on the agar medium. From this study, it could be concluded that the
two antagonists identified as Pseudomonas fragi and Bacillus pumilus have the
potential to control R. solani in rice.