Isolation, identification and chemical characterization of antifungal compounds isolated from rhizosphere microorganisms antagonizing the fungal pathogen: Rhizoctonia solani.

Four species of actinomycetes, 4 species of bacteria, 3 species of yeasts and 3 species of fungi were selected for their highest inhibitory and antagonistic activity and it was found that Streptomyces aurantiacus and Hansenula arabitolgenes were the most inhibitory followed by S. purpureus. It was also found that actinomycetes represent the most inhibitory group of the tested groups of microorganisms. One of the tested species produces 6 active components, 8 species, each produce 5 active components and the remaining other, each produce 4 active components. One of these active components was separated from the culture filtrates of 7 species. Two active components were separated from the culture filtrates of 6 species. One active component was separated from the culture filtrate of 5 species. The active components were purified and chemically analyzed to determine their chemical names, chemical formulae and molecular weight. New Egyptian Journal of Microbiology Vol. 17 (2) 2007: pp. 129-14