PURPOSE: A composition for preventing rice bacterial blight is provided to suppress rice bacterial blight which causes the biggest damage to rice plants, and to minimize damage of a rice growing region. CONSTITUTION: A composition for preventing rice bacterial blight contains dunaimycin D3S of chemical formula I. Dunaimycin D3S is derived from Streptomyces bottropensis MJM3389. The rice bacterial blight is a plant disease caused by Xanthomonas genus bacteria. A method for preparing dunaimycin D3S comprises the steps of: culturing Streptomyces bottropensis MJM3389； extracting the culture with an organic solvent； performing chromatography of the extract and obtaining an active fraction； and purifying the active fraction.본 발명은 스트렙토마이세스 보트로펜시스 MJM3389(Streptomycesbottropensis MJM3389) 균주로부터 생산되는 두나이마이신 D3S(Dunaimycin D3S)를 포함하는 벼흰잎마름병 방제용 조성물에 관한 것으로, 본 발명에 따른 벼흰잎마름병 방제용 조성물은 세계 3대 식물 중 하나인 벼의 가장 큰 피해를 야기하는 벼흰잎마름병을 억제하여 벼 재배 지역의 피해를 최소화할 수 있다.
