ISOLATION AND IDENTIFICATION OF AN ACTINOMYCETE STRAIN WITH BIOCONTROL EFFECT AGAINST Xanthomonas oryzae pv. oryzae CAUSING BACTERIAL BLIGHT DISEASE IN RICE

Abstract

     In this study, we performed experiments to screen and identify actinomycete strains that are antagonistic to Xanthomonas oryzae pv. oryzae causing rice bacterial blight disease. Among of 98 strains isolated, we obtained two strains capable of antagonizing X. oryzae pv. oryzae using agar diffusion plate method. The strain numbered 43 had a strong activity with a diameter of 22 mm clear zone of bacteria. The strain 43 showed white colonies after three days of incubation. Seven days of incubation the white colonies had grey borders, produced soluble pigments on the medium, grew well at 30°C and neutral pH, and adapted well to high salt concentration medium. The strain 43 was able toutilize different sources of carbon and nitrogen. Sequence analysis of 16S rRNA showed that strain 43 had a similarity of 100% compared to Streptomyces diastaticus subsp. ardesiacus. Based on morphology, culture, physiological and biochemical characteristics and molecular biological analyses the strain 43 was identified as S. diastaticus subsp. ardesiacus.