ANTIFUNGAL ACTIVITY OF EXTRACELLULAR METABOLITES PRODUCED BY SPOROTHRIX-FLOCCULOSA

The antifungal properties of extracellular compounds produced by the e piphytic fungus Sporothrix flocculosa were bioassayed against phytopat hogenic fungi on the basis of inhibition of spore germination, and myc elial growth and induction of cellular leakage. Following incubation i n stationary culture, S. flocculosa released antifungal metabolites in to the culture medium which were extractable with methylene chloride. When separated by thin layer chromatography, extracted metabolites yie lded a compound(s) at R(f) 0.65 which inhibited development of Cladosp orium cucumerinum and several other phytopathogenic fungi. Treatment o f Botrytis cinerea and Fusarium oxysporum f. sp. radicis-lycopersici ( FORL) with the same compound(s) greatly reduced spore germination and biomass growth of both fungi. Additionally, both B. cinerea and FORL l eaked electrolytes and proteins when grown in presence of the metaboli tes. Observations under electron microscopy revealed that FORL reacted to the presence of S. flocculosa metabolites by retraction of the pla smalemma and rapid disintegration of the cytoplasm. These reactions we re similar to the ones induced by conidia of S. flocculosa when applie d on powdery mildew fungi. These results provide strong evidence of th e production of antifungal compounds in vivo and of their role in the antagonistic properties of S. flocculosa.