Barium borate is a bactericide and fungicide. The copper is the primary bactericide and fungicide agent. It is also used in agriculture as a soil fungicide, plant bactericide, and acaricide. A bactericide or bacteriocide, sometimes abbreviated Bcidal, is a substance that kills bacteria. Soon after the discovery of ionizing radiation, therapeutic use and bactericide treatments were proposed. Glycyrrhizin compounds with bactericide effects in vitro were isolated from flowers. In industrial use, 2-furoic acid is a preservative, acting as a bactericide and fungicide. Sulfites are a source of sulfur dioxide (SO), a bactericide. Its action is mainly bacteriostatic, on highly sensitive strains it exerts a bactericide action. Lactic acid is a strong natural bactericide, with well-known antimicrobial properties. Hydramacin is a bactericide recently discovered in "Hydra"; it protects the outer layer against infection.