Effect of Volatile Oils on Fungal Growth and Their Toxins Production

Ten volatile oils of some plants were tested as antifungal agents against twelve fungal strains. Most fungal strains affected by volatile oils and the highest effect was found in case of Clove oil followed by Cinnamon oil and Basil oil according to the diameter of inhibition zone. The highest value of inhibition zone by Clove oil were found in case of Penicillium sp. followed by Aspergillus glaucus, A. niger, A. nidulans and E. nidulans to be 45.00, 34.52, 33.01,32.69 and 31.85 mm, respectively. Rose mary oil had no effect in all tested fungi except Penicillium sp. being 1.86 mm. Clove oil decreased the mycelium dry weight in all tested fungi. All fungi which not produced O-methylsterigmatocystin (OMST) did not produce any aflatoxins (B1, B2, G1 or G2). The presence of Ras cheese in the cultivation media stimulated A. nidulans and A. oryzae to produce aflatoxins. A. glaucus and A. ochraceus produced OMST and G2 in all cultivation media but did not produce aflatoxins B1, B2 or G1 in all cultivation media. The presence of clove oil in RCMCO medium of A. alliaceus, A. nidulans, A. niger, A. oryzae and Penicillium sp. prevented the production of aflatoxins. A. oryzae did not produce any of aflatoxins in all cultivation media. G. candidum produced all mycotoins in all cultural media except aflatoxin B2.