Antagonistic Potential of a Phosphate Solubilizing Bacteria (B. cereus PS1.1, B. cereus PS1.2, B. cereus PS1.4) Against the Patogent Fungus Ganoderma sp. Isolated from Basal Stem of Oil Palm (Elaeis guineensis Jacq.) with Rot Disease

Ganoderma sp. is a pathogenic fungus whose attack can cause basal stem rot disease of oil palm (Elaeis guineensis Jacq.). Disease control using phosphate solubilizing bacteria (PSB), namely Bacillus cereus can be an alternative to biological control. The purpose of this study was to determine the antagonistic ability of PSB (B. cereus PS1.1, B. cereus PS1.2, B. cereus PS1.4) in inhibiting the growth of Ganoderma sp. BP1 and changes in hyphal morphology of Ganoderma sp. BP1 after antagonistic testing. The research was conducted from January to May 2023 at the Microbiology Laboratory, Department of Biology, Faculty of Mathematics and Natural Sciences, Tanjungpura University, Pontianak. Antagonist testing used a completely randomized design (CRD) with the treatments consisted of Ganoderma sp. BP1 (negative control), 1% hexaconazole fungicide (positive control), PSB isolates PS1.1, PS1.2 and PS1.4. The test method used the dual culture on Sabouraud Dextrose Agar (SDA) media with each treatment repeated four times so that 20 experimental units were obtained. The results showed that PSB isolate PS1.4 had strong inhibition with an inhibition zone diameter of 11.01 mm, while isolates PS1.1 and PS1.2 had moderate inhibition with inhibition zone diameters of 9.43 mm and 9.45 mm, respectively, against Ganoderma sp. BP1. Hyphal morphology changes in of Ganoderma sp. BP1 that occurred after the antagonist test consist of lysed hyphae, twisted hyphae, hook-like hyphal tips, curly hyphae, bulbous hyphae, branched hyphae and bent hyphal ends.