**2.2 Assay of antagonism of bacterial spp. to** *X. oryzae* **pv.** *oryzae* **by dual culture method**

Antimicrobial activity of antagonistic strains of *Pseudomonas* spp./*Bacillus* spp. were determined by agar diffusion technique method [55] with some modifications. Antagonistic bacterial suspension was spot inoculated (5 μl of 10<sup>8</sup> CFU/ml) at three places on the NBY plates that were prior inoculated with *X. oryzae* pv. *oryzae* cell suspension (10<sup>8</sup> CFU/ml � optical density: 0.3). The plates were incubated for 7 days post inoculation at 28°C. Then *X. oryzae* pv. *oryzae* growth inhibition by the antagonistic bacterial isolates indicated by clear halo zones were measured with a ruler in mm. The percent growth inhibition of *X. oryzae* pv. *oryzae* by bacterial isolates was calculated as follows:

Growth inhibition %ð Þ¼ Total diameter Colony diameter <sup>þ</sup> clear halo zones �Colony diameter x 100*=*Total diameter

(1)
