The antifungal and antiaflatoxigenic properties of Thymus vulgaris essential oil (TEO) were evaluated
upon Aspergillus flavus ‘‘in vitro’’. Suspension containing 106 of A. flavus were cultivated with TEO in
concentrations ranging from 50 to 500 lg/mL. TEO reached minimum inhibitory concentration (MIC)
and minimum fungicidal concentration (MFC) at 250 lg/mL. Inhibition of ergosterol biosynthesis was
detected at a concentration of 100 lg/mL of TEO. Morphological evaluation performed by both light
microscopy and scanning electron microscopy showed that antifungal activity of TEO could be detected
starting at a concentration of 50 lg/mL and the fungicide effect at a concentration of 250 lg/mL. TEO
completely inhibited production of both B1 and B2 aflatoxins (AFB1 and AFB2) at a concentration of
150 lg/mL. This way, fungal biomass development and aflatoxin production were dependent on TEO
concentration. Therefore, TEO was capable of controlling the growth of A. flavus and its production of
aflatoxins.