Evaluation of antifungal activity of some natural essential oils against fungal pathogens associated with maize grains

Abstract

Mycotoxin-producing moulds which considered as common maize grains contaminants are presented in the genera Fusarium, Aspergillus and Penicillium. One of the natural and safe ways to protect grains from mould contamination is the use of essential oils. The antifungal activity of thyme, citral, methyl anthranilate, rosemary and clove, essential oils (EOs) against Fusarium. moniliforme, Aspergillus niger, Penicillium sp., Aspergillus flavus and Aspergillus terreus was evaluated in direct contact assay. All EOs showed significant impact on mycelial growth and spore germination inhibition. Thyme showed the best inhibitory effect while, methyl anthranilate and rosemary were the most effective EOs for spore germination inhibition. The effect of EOs added to grains in different application methods (volatile and carrier contact assays) were evaluated. In volatile assay, frequency of F. moniliforme and A. niger isolated from maize grains was greatly inhibited by rosemary, P. sp. was most affected by methyl anthranilate, and A. flavus growth reduced by thyme. On the other hand, frequency of F. moniliforme and Penicillium. sp. were greatly inhibited by the clove at EC50 =4.5009 and EC90 =6.9351mg/mL, while A. niger was most affected by citral as well as rosemary and methyl anthranilate leaded to the major frequency reduction of A. flavus. Our results cleared that vapor contact assay had stronger antifungal activity as a post-harvest treatment than carrier contact assay. These results suggested that fungi can be controlled by EOs, especially clove and thyme oils.