BIOAUTOGRAPHY SHOWS ANTIBIOTic PRODUCTION BY SOIL BACTERIAL ISOLATES ANTAGONISTIC TO FUNGAL DRY ROT OF POTATOES

Twenty bacterial antagonists of postharvest dry rot of potatoes (caused by Fusarium sambucinum) were screened for the production of antibiotics by bioautography. Samples of liquid cultures of bacterial strains harvested at three growth times and extracted with three solvents at three pHs were used to directly detect antibiotics inhibitory to F. sambucinum grown on the surface of thin-layer chromatography plates. All of the bacterial isolates tested produced one or more antifungal compounds. Knowledge of the role of the antibiotics in biological control mechanisms is expected to influence the design of successful methods of mass production and formulation of these bacterial strains as biocontrol agents. .