Agriculture & Food, Volume 9, 2021

Abstract: Enniatins are emerging mycotoxins produced by Fusarium species. They are frequently found as contaminants in cereal grains in recent years. The synthesis of these secondary metabolites is often a response to biotic and abiotic stresses. Therefore, the introduction of fungicides into the environment of toxigenic fungi can lead to an increase in mycotoxin accumulation. The search for molecules with both antifungal and antimycotoxigenic activities is a challenge to preserve food safety. Essential oils (EOs) have a promising potential as natural fungicides and should be used both to control fungi and/or their mycotoxin production. In the present work, we extracted the essential oil of Tunisian Thymus capitatus and tested its effect in vitro on two enniatin-producing Fusarium strains when placed in contact with the mycelium in solid medium or used as a fumigant. In agar medium, contact tests measured with two different sets of EOs for a strain of Fusarium avenaceum provided an IC5O of 0.05 μL EO mL-1. For another strain of Fusarium sp. it was found an IC50 of 0.08 μL EO mL-1. Fungistatic activity induced no overproduction of enniatins and in contrast, decreases of 55% were found in some samples. Volatile components diffusing in a sealed container also had fungistatic activity that was both dose (5 to 25 μL 1.5 L-1) and time (6 to 24 days) dependent. No fungal acclimation to the EOs and no persistent effect of the EOs were observed, but the decrease in protective effect with increasing incubation time was probably due to EOs alterations.