STUDY OF METABOLITES FROM CULTURE FILTRATES OF SOME ANTAGONISTIC YEASTS ON SPORE GERMINATION OF P. digitatum

Three antagonistic yeasts i.e. Candida famata, Debaryomyces hensenii and Rhodotorula mucilaginosa were cultured and their culture filtrates (non –volatile) were harvested. Half of the culture filtrate was filter sterilized (FS) and remaining half was autoclave sterilized (AS) and the effects of both FS and AS culture filtrates of all three yeasts on spore germination of Penicillum digitatum, dangerous pathogen of citrus were recorded. This experiment showed that filter sterilized culture filtrate (FS) of all yeast antagonists inhibited spore germination of P. digitatum. FS of C. famata gave maximum percentage (87.00±4.56a) of inhibition of spores of P. digitatum followed by D. hansenii (79.75±5.00a) and R. mucilaginosa (69.05±3.45b). On the other hand, AS of all three yeasts were non effective to inhibit the spore germination indicating that chemicals present in the culture filtrates were heat labile. It may be concluded that all antagonistic yeasts may produce and secrete heat labile antibiotics or toxic substances or enzymes in their culture filtrates in vitro that inhibited spore germination of P. digitatum.