Antifungal Activity of Methanol-Extracted Secondary Metabolites of Rhizobacteria Isolated from Rhizosphere of Oil Palm Trees Against Ganoderma Boninense Pat.

Abstract

Several rhizobacteria were isolated from the rhizosphere of healthy oil palm trees showed prospective ability as biocontrol agent against pathogenic fungi Ganoderma boninense Pat. The fungus is the causal agent of basal stem rot (BSR) disease can cause yield reduction up to 80%. Therefore, searching for effective compound to control the disease is a continuous process. Rhizosphere bacteria isolates were grown on ISP2 agar media and incubated for 14 days at room temperature. The media with fully grown cultures were cut into cubes and added with methanol. It was shaken and the bacterial cells were then removed through centrifugation and series of filtration. The final filtration was conducted using 0.2 μm to sterilize the filtrate. The filtrates were subjected for antifungal activity against G. boninense using agar well diffusion. The result showed that the crude metabolites produced by the rhizosphere bacteria demonstrated the ability to inhibit the growth of G. boninense in the agar diffusion method. The highest inhibition reached 51.63%. Furthermore, G. boninense mycelia were also experienced malformation by the presence of the secondary metabolites. The isolated rhizosphere bacteria showed promising ability to produce antifungal compounds which were able to inhibit the growth of G. boninense as well as causing the morphological changes of its mycelia.