Abstract
Chaetomium trilaterale var. diporum RC-5 was isolated from sclerotia of Sclerotinia sclerotiorum buried in soil in Okinawa Prefecture. Since the isolate inhibited mycelial growth of S. sclerotiorum on PDA medium, the purification of the antifungal substance was undertaken. The antifungal substance was produced in modified Richards medium. The substance was isolated by extraction with chloroform and thin layer chromatography. Its molecular formula was determined as C31H35O8N (mol wt 549) on the basis of elementary analysis and fast atom bombardment mass spectrometry (FAB-MS). Mycelial growth of S. sclerotiorum and Botrytis cinerea was inhibited intensively and their hyphal tips were branched abnormally by the treatment with antifungal substance. Their ED50 values on PDA medium were ca. 10ng/ml, and they were more than 20 times stronger than that of cycloheximide. While, the mycelial growth of other indicators such as Pyricularia oryzae, Sclerotium hydrophilum and some isolates of Rhizoctonia solani was not inhibited even at 100 μg/ml.
