We thus focused our attention on yeast extracellular glycolipid biosurfactants, mannosylerythritol lipids (MEL), which are abundantly produced from vegetable oils by Pseudozyma yeasts. As MEL exhibit not only excellent interfacial properties but also various antimicrobial actions, they are expected to show inhibitory effect on the infection of phytopathogenic fungi, through the modification of plant surface and the antifungal activity.
In this study, we investigated the effect of MEL against the wheat powdery mildew fungus Blumeria graminis. The conidia of the fungus was spread over on a water agar or plastic plate, where the surface was treated with MEL aqueous solution (0.1 wt%), and then the conidial germination was observed. As the result, the conidial germination was significantly suppressed by the addition of MEL. Interestingly, the suppression of the conidial germination was also observed on the leaves of wheat treated with MEL. Accordingly, MEL should have potential as a new biocontrol agent for phytopathogenic microorganisms, and thus lead new suppression technique that make the use of pesticides reduced.