A Novel Antagonistic Strain of Sepedonium chrysospermum

Fungi of the genus Sepedonium have been studied for their properties as antagonist agents of various plant pathogens, as well as antibiotic and pigment producers. We investigated the antimicrobial ability of S. chrysospermum strain 704 isolated from fruit bodies of wild basidiomycetes and found to be not pathogenic on cultivated mushrooms. A strong antagonistic activity versus different pathogenic fungi and a high level of production of enzymes and antibiotic compounds were observed. The best growth conditions for the production of specific hydrolytic enzymes were determined. From fungal culture filtrate we purified and characterised a metabolite that strongly inhibit spore germination and hyphal growth of the necrotrophic pathogen Botrytis cinerea. The metabolite was identified as a 3,6-dimethyl--resorcylaldehyde, and showed a strong inhibition of the pathogen at concentrations starting from 0.05 ppm. Furthermore, a low level of phytotoxicity of the purified antibiotic, analysed by infiltration in bean leaves, was observed.