Characterisation of Endophytic Bacteria that Inhibit the Growth of Ganoderma Boninense, a Fungus That Causes Basal Stem Rot Disease in Oil Palm Trees

Kuan, Jo Ann (2020) Characterisation of Endophytic Bacteria that Inhibit the Growth of Ganoderma Boninense, a Fungus That Causes Basal Stem Rot Disease in Oil Palm Trees. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Ganoderma boninense, a pathogenic fungi, is the causal agent of the deadly basal stem rot disease in oil palm trees. The symptoms of the disease are not detectable in the early stages, making it difficult to eliminate the disease. The objective of this study is to characterise four endophytic bacteria, namely SL14 (1), SL14 (2), SL22 (YC), and SL22 (LLT), that were isolated as promising biological control agents against the fungus. Through dual culture assay, all the bacteria were shown to be capable of inhibiting the growth of the fungi. SL14 (2), SL22 (YC), and SL22 (LLT) were demonstrated to be chitinolytic bacteria as purple hydrolysing zones were formed on colloidal chitin bromocresol purple agar after inoculation of bacteria. Dinitrosalicylic acid (DNS) assay was used to evaluate the inhibitory potential of each bacterial strain. G. boninense released high concentrations of N-acetylglucosamine (GlcNAc) monomer when the fungi were cultured with SL14 (2), SL22 (YC), and SL22 (LLT). These results suggest that these three bacterial strains suppress the growth of G. boninense using chitinase enzyme. SL14 (1) was a non-chitinolytic bacteria and low concentration of GlcNAc was measured after DNS assay. This suggests that the bacteria inhibited G. boninense through another mechanism. Through 16S rRNA gene amplification and gene sequencing, SL14 (1), SL14 (2), SL22 (YC), and SL22 (LLT) were identified as A. faecalis strain MUB14, A. faecalis strain FDAARGOS_491, Providencia sp. strain SMKBRT_TS9, and Providencia vermicola strain Gol12, respectively. In conclusion, A. faecalis strain FDAARGOS_491, Providencia sp. strain SMKBRT_TS9, and Providencia vermicola strain Gol12 exhibited greater inhibitory against G. boninense.