The objective of the research “Examination of antibacterial activity of actinomycetes isolates on Colletotrichum sp. causing rot fruit disease on Jackfruit” was to screen actinomycetes isolates able to control rot fruit disease on Jackfruit fruit caused by Colletotrichum sp. fungus. The results of antagonistic ability found that 5 actinomycetes isolates CL-TG1, CL-TG 15, CL-TG 24, TP-TG 12 and TP-TG24 showed higher stabler antagonistic ability and have radiuses of inhibition zones reaches 15.00mm; 10.60mm; 16.40 mm; 15.00mm and 15.00mm, respectively and antagonistic efficacy reaches 66.65%; 69.28%; 76.29%; 66.42% and 67.61%, respectively at 7 days after co- inoculation. The results of inhibiting appressorium formation of Colletotrichum sp. found that 5 actinomycetes isolates (CL-TG1, CL-TG 15, CL-TG 24, TP-TG 12 and TP-TG24) have ability of inhibiting appressorium formation and CL-TG 24 isolate has the lowest of appressorium formation reaches 13.75 (appressorium) and the highest inhibition effecicacy reaches 90.93% at 7 days after testing. Beside, chitin degradation potential of 5 actinomycetes isolated (CL-TG1, CL-TG 15, CL-TG 24, TP-TG 12 and TP-TG24) were examined with 5 replications under laboratory condition. The results indicated that, actinomycetes isolates CL-TG 24 has expressed the chitinlytic activity, with the chitin lyses halo radius of 20.0mm at 7 days after treatment.

Keywords: Actinomycetes, rot fruit disease on Jackfruit, appressorium, Colletotrichum sp.,chitin.