Oil Palm Soil Microbial Diversity Study Using Molecular and Biochemical Techniques and Detection of Potential Biocontrol Agents against Ganoderma Boninense

Tan, Pauline Xiao Phing (2022) Oil Palm Soil Microbial Diversity Study Using Molecular and Biochemical Techniques and Detection of Potential Biocontrol Agents against Ganoderma Boninense. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Oil palm (Elaeis guineensis) has been widely cultivated throughout Malaysia due to its beneficial properties in various industries and the huge revenue brought to the country. However, a white-rot fungus known as G. boninense has been a serious pathogen causing huge losses to the palm oil industries every year. With such devastating losses, there’s still no effective methods to conquer this basal stem rot (BSR) disease caused by G. boninense. As such, the soil which is one of the largest biologically active reservoirs is targeted for the discovery of new microorganisms to function as biocontrol agents against G. boninense. Having a thorough understanding of the soil microbial communities might provide insight into relationships between oil palm, soil microflora, and the causal agent of BSR disease. In this study, both molecular and biochemical methods were conducted to profile the soil microbial diversity under oil palms aged 5 (JJ soil) and 20 (JK soil) years old followed by the detection of potential biocontrol agents. For molecular technique, three DNA extraction methods were conducted with the modified conventional extraction giving a better result in terms of quality, purity, and PCR steps. Next, the V3-V4 region of 16s rRNA was targeted in next-generation sequencing followed by discussion of the potential biocontrol agent. For the biochemical method, a total of 124 Bacillus spp. and 165 Pseudomonas spp. were successfully recovered from the soil with their biocontrol properties discussed. Six Bacillus sp. and four Pseudomonas sp. were identified to show antagonistic properties towards G. boninense. Finally, TSA plate was performed to discover the soil microbial diversity and JK soil appears to have a higher Shannon and Simpson index. Factors such as stability, structure, and physicochemical properties of JK soil are likely to affect the microbial population and diversity. In summary, the soil is a rich substance with great potential for the discovery of different microbial strains that might be useful in suppressing pathogens in oil palm