Involvement of Irreversible Vacuolar Membrane Fragmentation in the Lethality of Food Emulsifier Diglycerol Monolaurate against Budding Yeast.

Diglycerol monolaurate (DGL) has been manufactured as a novel type of food emulsifier and is being considered for further application as a food preservative. DGL lethality was thus examined against Saccharomyces cerevisiae as a model of a yeast that causes food spoilage. In spite of its molecular structure as a nonionic surfactant, DGL could exhibit lethality at a concentration lower than that which caused disruptive damage to the yeast plasma membrane. DGL lethality was rather accompanied by a dynamic intracellular event such as a marked vacuolar membrane fragmentation. In DGL-treated cells, the tiny dots or particles of fragmented vacuolar membranes failed to fuse into the original large rounded architecture after its removal from medium, which were distinguished from those generated as a result of vacuolar fission normally accelerated under hyperosmotic conditions. Such an irreversible structural damage of the organelle membrane was considered a cause of DGL lethality.