Glycosyltransferase; part of the gene cluster that mediates the biosynthesis of mannosylerythritol lipids (MELs), surface-active substances that enhance the availability of water-insoluble substrates (Probable) (PubMed:31923270). MMF1 is directly involved in the secretiopn of MALs (Probable). Expression is induced when cells are grown in cultures containing vegetable oil as the carbon source. MELs not only have high potential as eco-friendly biosurfactants due to their excellent surface activity, but also have attracted considerable recent interest because of thei runique properties, including self-assembly, anti-tumor and cell differentiation induction activities, and moisturizing and hair-repairing properties. Belongs to the major facilitator superfamily.