Potential of actinobacteria as biocontrol agents to Xanthomonas oryzae pv. oryzae in vitro

Xanthomans oryzae pv. oryzae (Xoo) is a pathogen that causes bacterial leaf blight in rice plants.Biological control using microorganisms, one of which incorporates actinobacteria, is one of the most extensively used control techniques. This work aimed to find actinobacteria isolates from rice that can inhibit Xoo growth in vitro. A Completely Randomized Design (CRD) was employed in this experiment, with 14 treatments and three replications. There are 13 isolates used: Act-Hr 49, Act-Hr 21, Act-Hr 24, Act-Pha 4, Act-Mn2, Act-LB3, Act Pha 2.3, Act Pha 3.4, Act-Pha 3.3, Act-Hr 47, Act Pha 3.5, Act-Krj 21, Act-SK2 and control (Xoo without Actinobacteria treatment). The ability of actinobacterial isolates to reduce Xoo growth in vitro and the enzyme activity of each isolate were measured. The study revealed that three Actinobacteria isolates, Act-LB3, Act-Mn2, and Act-Pha4, could potentially suppress Xoo bacteria’s growth with inhibition indices ranging from 12 mm to 15 mm Act-LB3 isolate produced catalase enzyme, while Act-Pha4 isolate produced both catalase and protease enzyme. The results indicate that actinobacteria from the rice rhizosphere could produce antibacterial metabolites and enzyme activity.