A NEW MICROBIAL SECONDARY METABOLITE INHIBITORY TO THE GROWTH AND SPORULATION OF Ceratocystis paradoxa (DADE) MOREAU

• Main Author: Made Sudana, I
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/8199
• Institution: Institut Teknologi Bandung

Abstract: <br /> <br /> <br /> <br /> <br /> <br /> Ceratocystis paradoxa is a destructive pathogen of coconut palm (Cocos nucifera L.) and snake fruit (Salacca edulis Reinw.) in Indonesia. Owing to the general ineffectiveness of commercial fungicides and other control measures currently employed in combating this pathogen, a systematic search for indigenous biological control agents was undertaken. <br /> <br /> <br /> <br /> <br /> This survey yielded three candidates, Fusarium acuminatum Ell. et Everhart, Fusarium xysporum Schlech., and Pseudomonas stutzeri (Lehmann) Sijderius, that produced extracellular metabolites inhibitory to growth and sporulation of C. paradoxa. Extracellular protein and non-protein compounds were separated by ultrafiltration using polysulfone membranes. Subsequent bioassays revealed that only the non-protein compound had any inhibitory effect on C. paradoxa. <br /> <br /> <br /> <br /> <br /> The non-protein compound produced by a strain of P. stutzeri, isolated from soil on Tangkuban Perahu in West Java, exhibited the highest degree of inhibition and was singled-out for subsequent study. <br /> <br /> <br /> <br /> <br /> Extraction of the spent culture medium with ethyl acetate yielded a crude extract that was inhibitory to spore formation and mycelial growth of the pathogen at 500 ppm concentration due to the extract inhibit the synthesis of nucleic acid and protein, and the activity of glucose-6-phosphate dehydrogenase, succinate dehydrogenase, pectinase, and cellulase. <br /> <br /> <br /> <br /> <br /> Active compounds were separated from the crude extract by thin-layer and silica gel column chromatography. Pure compounds were obtained by HPLC using a methanol/water (40:60) solvent, and a 4.6 X 200 mm Wakosil column, then bioassayed individually against C. paradoxa for activity. Pure active compounds were determined by scanner TLC and analytical HPLC. Structure of the compounds was determined using ultraviolet, infrared, mass and HNMR spectroscopy. From the crude extract, three pure compounds were obtained. The fact that it was possible to isolate only very small amounts of the pure compounds, spore germination was used as the criterion for measuring bioactivity. The compounds, designated 1, 2 and 3 were found to inhibit spore germination at 250 ppm, 500 ppm, and 62.5 ppm, respectively. The most active compound (3) was subsequently identified as 4-methoxyphenethyl acetate. The structure of compounds 1 and 2 could not be determined due to the production of haystack-peak spectra of HNMR, however their molecular weights were 414 and 260, respectively, and both possessed a phenolic and a ketone group. <br />