Antifungal Activity of Basil Oil (Ocinum basilicum) on Radial Growth of Aspergillus niger

Basil is a widely used plant in the spice and various industries such as cosmetics and medicine. It has been traditionally used in medicine as a carminative, lactation enhancer, stomachic, and antispasmodic. Additionally, it has been reported that its essential oil has different biological activities such as antibacterial, antifungal, and antioxidant. Aspergillus niger is a phytopathogen commonly known as "black mould," which contaminates stored foods and causes postharvest decay of fresh fruits, grains, and produce worldwide. While this mould is valuable from a pharmacological perspective due to its production of organic acids, proteins, enzymes, and other secondary metabolites, its spores can also cause allergies and asthma in humans and animals. Therefore, the study was conducted to investigate the potential of basil oil as a preventive or therapeutic agent in the food industry, agriculture or medical applications. For this purpose, Aspergillus niger cultures that were 3–5 days old were inoculated onto petri dishes containing 1%, 2%, 5%, and 10% basil oil mixed with PDA (which included 3% dimethyl sulfoxide). After five days of incubation, the diameters of the colonies were measured. The effect of basil oil on Aspergillus niger radial growth was calculated considering the control group. The study was carried out in three replications. Surprisingly, the results showed that basil oil did not inhibit the radial growth of Aspergillus niger; instead, it increased the radial growth by 7.01% at the 5% concentration and by 27.50% at the 1%concentration. These findings suggest that the use of basil oil as an antifungal agent may not be effective in all cases and may promote the radial growth of Aspergillus niger under certain conditions. Therefore, to determine its limitations and potential risks, it is crucial to carefully assess and consider specific conditions when using basil oil preventively or therapeutically, particularly in the food industry and agriculture.