Antimicrobial potential of endophytic bacteria against bacterial leaf blight, Xanthomonas oryzae pv. oryzae

Rice is perhaps the most widely cultivated food crop world over, whose production is constrained by diseases of fungal, bacterial and viral origin. The bacterium Xanthomonas oryzae pv. oryzae (Xoo) or previously known as Xanthomonas campestris pv. oryzae for example, is the causal pathogen of the bacterial leaf blight disease (BLB) of rice in Asia (Swings et al. 1990). Endophytic bacteria may have several potential applications in various sectors of biotechnology including agriculture. Bacterial endophytes need to be explored for their potential applications in agricultural biotechnology. Hence, this study was undertaken to explore the antagonistic antimicrobial potential of endophytes isolated from rice against the pathogenic bacteria, Xanthomonas oryzae pv. oryzae. In this study, plant samples were collected from rice field of Integrate Agriculture Development Area (IADA) Barat Laut in Sawah Sempadan, Kuala Selangor, Malaysia. Pathogenic bacteria, Xoo were isolated using Peptone Sucrose Agar (PSA) media. Endophytic bacteria were isolated using Nutrient Agar (NA) media via serial dilution method from different parts of rice such as root, sheath, leaves, and root rhizosphere. Potential endophytic bacteria screened by dual culture test were conducted using agar well diffusion method (Azoro et al., 2002) in Mueller Hinton Agar (MHA) media. Endophytic bacterium B3 and D1 showed positive inhibition against Xoo. The two bacteria showed activity against tested bacterial pathogen but in a weak state. The isolates are not susceptible to be chosen as one of the effective biological control against Xoo