Antifungal Activity of Phyllosphere Actinobacteria against Pyricularia oryzae

Abstract

Secondary metabolites produced by microbes provide many pharmaceutical agents such as antibacterial, antifungal, antiviral and immunosuppressant. Antifungal plays important role in inhibit the fungus which detrimental to agriculture and human health. The excess usage of antifungal inducing many fungus species to became resistant so that development of new antifungal is quite important. Actinobacteria are Gram positive bacteria which known to have produced 45% of the total metabolites produced by microbe and 70% of total metabolites produced by bacteria. As many as 33% of the metabolites produced by Streptomyces sp., including metabolites which have antifungal activity. Some phyllosphere actinobacteria are known to have potential antifungal activity. The purposes of this study were to screen rice phyllosphere actinobacteria that has antifungal activity against Pyricularia oryzae (Po) causes rice blast disease and to observe the responses of the hyphae of actinobacteria isolates in vitro. A total of eight isolates had antifungal activity against Po. STG 11 had identified as Streptomyces has the highest inhibitory activity that was 72.5%. The response of Po hyphae towards STG 11 indicate a disruption of growth direction of the hyphae which tend to form a curve. Two isolates had chitinolytic activity and six isolates had no hemolytic avtivity.