CONTROL OF Pythopthora palmivora THE CAUSAL AGENT OF BLACK POD DISEASE ON CACAO WITH ENDOPYTHIC BACTERIA

• Main Author: Fitriyanti, Ersalina
• Format: Theses
• Language: Indonesia
• Subjects: Ilmu hayati ; Biologi
• Online Access: https://digilib.itb.ac.id/gdl/view/36131
• Institution: Institut Teknologi Bandung

Indonesia's cacao production decreases from year to year. One contributing factor is the frequency of black pod disease caused by Pythopthora palmivora. The purpose of this study was to obtain endophytic bacterial isolates from cacao plant which have the ability to antagonize P. palmivora and to evaluate the mechanisms. This research was initiated from isolation of endophytic bacteria, followed by in vitro screening of their ability to antagonize P. palmivora in a dual culture, evaluating the inhibition mechanisms (enzyme and secondary metabolites activity), and identification of selected isolates based on ribosomal DNA (16sRNA) analysis. The samples were collected from healthy garden plant in Jatinangor area and cacao plantations in Rajamandala. Endophyte isolation was carried out by using a standard procedure after surface sterilization of the samples. Overall, there 70 isolates were obtained from leaves, branches, pod and root samples. Among them, 9 isolates showed the positive antagonism effect against P. palmivora. Bacterial isolates RMk2 gave the highest activity (69.56%) and was selected for further study. The bacterial isolate was identified as Bacillus megaterium based on molecular identification using forward primer 16S (5’– AGAGTTTGATCCTGGCTCAG-3’), reverse primer 16S (5’–GGTTACCTTGTTACGACTT – 3’).The capability of B. megaterium to inhibit the growth of P.palmivora was supported by the activity of crude enzyme in degrading cell component of the pathogen as well as by crude metabolite extracts from the bacteria. The optimum activity of crude enzyme extracts from isolates RMk2 was obtained at temperatures of 45°C (0,126 activity unit U/ml) and pH 7.5 (activity unit of 0,124 U/ml). The positive antifungal activity of crude metabolic compounds was obtained from n-Butanol extract with a Rf value of 0.5 showed inhibiting activity.