against food spoilage and bovine mastitis. Thymol demonstrates in vitro post-antibacterial effect against the test strains E. coli and P. aeruginosa (gram negative), and Staphylococcus aureus and B. cereus (gram positive). This antibacterial activity is caused by inhibiting growth and lactate production, and by decreasing cellular glucose uptake. Thyme essential oil is useful in preservation of food. The antibacterial properties of thymol, a major part of thyme essential oil, as well as other constituents, are in part associated with their lipophilic character, leading to accumulation in bacterial membranes and subsequent membrane-associated events, such as energy depletion. The antifungal nature of thymol against some fungi that are pathogenic to plants is due to its ability to alter the hyphal morphology and cause hyphal aggregates, resulting in reduced hyphal diameters and lyses of the hyphal wall. Uses Thymol during the 1910s was the treatment of choice for hookworm infection in the United States. People of the Middle East continue to use za'atar, a delicacy made with large amounts of thyme, to reduce and eliminate internal parasites. It is also used as a preservative in halothane, an anaesthetic, and as an antiseptic in mouthwash. When used to reduce plaque and gingivitis, thymol has been found to be more effective when used in combination with chlorhexidine than when used purely by itself. Thymol is also the active antiseptic ingredient in some toothpastes, such as Johnson & Johnson's Euthymol. Thymol has been used to successfully control varroa mites and prevent fermentation and the growth of mold in bee colonies. Thymol is also used as a rapidly degrading, non-persisting pesticide. Thymol can also be used as a medical disinfectant and general purpose disinfectant. List of plants that contain thymol Illicium verum Euphrasia rostkoviana Lagoecia cuminoides Monarda didyma Monarda fistulosa Mosla chinensis, Xiang Ru (香薷) Origanum compactum Origanum dictamnus Origanum onites Origanum vulgare Satureja thymbra Thymus glandulosus Thymus hyemalis Thymus vulgaris Thymus zygis Trachyspermum ammi Toxicology and environmental impacts In 2009, the U.S. Environmental Protection Agency (EPA) reviewed the research literature on the toxicology and environmental impact of thymol and concluded that "thymol has minimal potential toxicity and poses minimal risk". Environmental breakdown and use as a pesticide Studies have shown that hydrocarbon monoterpenes and thymol in particular degrade rapidly (DT50 16 days in water, 5 days in soil) in the environment and are, thus, low risks because of rapid dissipation and low bound residues, supporting the