Characterisation and Identification of Actinomycetes with Potential to Suppress Fungal Pathogen of Durian

Foong, Ker Shin (2019) Characterisation and Identification of Actinomycetes with Potential to Suppress Fungal Pathogen of Durian. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Durian is one of representative produces of Malaysia. Increasing demands and market price have pushed the durian production to a new height. However, pests and diseases of durian have high potentials to affect the production. Instead of relying on chemical pesticides to control the pests, a more environmental friendly ways such as biological control targeting underutilized microorganisms were sought. This will be the main aim of my study besides isolating fungal pathogens of durian and characterizing metabolites produced by Actinomycetes that are responsible in suppressing the fungal pathogens. Four soil samples were collected from durian plantation located at Gambang, Pahang for fungal pathogens and actinomycetes isolation purposes. Two suspected fungal pathogens, Unknown fungus B (UB) and Unknown fungus W (UW) were successfully isolated using baiting technique. Soil samples A, B and D have higher population of actinomycetes (ranging from 3.67-6.67 x 105 cfu/g) as compare to sample C. A total of 37/42 actinomycetes were isolated and subjected to dual culture challenge test to determine the antagonist effect towards the two suspected fungal pathogens. Results were recorded by calculating percent inhibition of radial growth (PIRG). UB fungus was observed to be inhibited by 16 actinomycete isolates with A2 and D6 have the lowest PIRG (11.25%) and highest PIRG (43.87%) respectively. As for UW fungus, 6 isolates shows antagonist effect. B16 has the highest PIRG (45.42%) while C3 has the lowest PIRG (17%). 16srRNA extraction was performed for actinomycete isolates that shows antagonist effect. The DNA extracts were then sent out for sequencing followed by identification via Basic Local Alignment Search Tool (BLAST) from National Center for Biotechnology Information (NCBI). Suspected fungal pathogens were identified in the similar manner. 37.5% of the isolated actinomycetes were Streptomyces sp. and another 37.5% are Bacillus sp. Meanwhile, suspected fungal pathogens were identified as Mortierella sp. and Diaporthe sp.