Streptomyces sp. as Potential Biocontrol for Fungal Phytopathogen, Ganoderma boninense
Muhammad Asyraff Abd Samad, Abdul Munir Abdul Murad, and Izwan Bharudin*
Department of Biological Sciences and Biotechnology, Faculty of Science and Technology,
Universiti Kebangsaan Malaysia, UKM Bangi, 43650 Malaysia
Malaysia and Indonesia contribute more than 80% to the global palm oil market. However, the sustainability of the oil palm plantations is threatened by a disease known as Basal Stem Rot (BSR) caused by fungal pathogen, Ganoderma boninense. Nearly 60% of plantation areas were reported with the disease, causing huge economic losses to both countries (up to USD500 million/year). To date, there are no effective methods to halt the continuing spread of the fungus. Thus, we aim to identify the potential microorganisms and determine their specific compounds (volatiles and non-volatiles) with antifungal properties that can inhibit the growth of the fungal pathogen. The dual-culture assay method was used to determine the ability of Streptomyces sp. to secrete the non-volatile compounds whereas the dual-chamber assay was used to identify the non-volatile compounds. Gas chromatography-mass spectrometry (GC-MS) analysis was used to identify the volatile organic compounds (VOCs) whereas liquid chromatography-mass spectrometry (LC-MS) analysis was used to identify the non-volatile compounds produced by the microorganism. Several known antifungal VOCs produced such as dimethyl disulfide (DMDS) and 2-heptanone, 6-methyl were identified from the GC-MS analysis. Moreover, LC-MS analysis also identified a few known antifungal compounds such as aureothin and 3-amino-2-nitrophenol. Furthermore, the introduction of Streptomyces sp. to the co-culture (oil palm-G. boninense) has reduced the BSR symptoms drastically in the artificial infection assay. Thus, it shows that Streptomyces sp. is a promising candidate to be used as a biocontrol agent against G. boninense and will be applicable for BSR disease management and prevention.