Contamination of Wheat, Barley, and Maize Seeds with Toxigenic Fusarium Species and Their Mycotoxins in Tunisia

Background: Fusarium is a worldwide distributed fungal genus. It includes different species pathogenic to cereals among others crops. Some of these species can also produce toxic compounds toward animals and humans. Objective: In this work, occurrence of fumonisins B-1+B-2, zearalenone, type A trichothecenes (T-2 and HT-2 toxins), and type B trichothecenes (deoxynivalenol[DON] and nivalenol[NIV]) was studied in 65 samples of stored and freshly harvested wheat, barley, and maize collected in Tunisia. Methods: Mycotoxins analyses were performed by using gas chromatography for type B trichothecenes and HPLC for other mycotoxins. Obtained results were compared with the presence of mycotoxigenic species considered responsible for their synthesis by using species-specific polymerase chain reaction (PCR). Results: Fumonisins occurred in 20.83% of wheat, 40% of barley, and 57.14% of maize samples, at levels exceeding European limits and suggesting a risk in Tunisian cereals, especially maize. Zearalenone, DON, NIV, and T-2+HT-2 toxins were detected at lower values in only wheat and barley samples. PCR protocols showed the predominance of F. uerticillioides especially in maize, and occurrence of F. equiseti and F. graminearum in wheat and barley, and F. proliferatum in only two maize samples. A very consistent correlation was found between the detection of F. uerticillioides and the contamination by fumonisins, as well as between the presence of F. graminearum and the contamination by zearalenone, DON, and NIV in the analyzed cereals. Conclusions: Consequently, the detection of Fusarium species with the current PCR assays strategy in wheat, barley, and maize grains may be considered predictive of their potential mycotoxin risk in these matrices. Highlights: This work is the first to report information on the occurrence of fumonisins, trichothecene, and ZEN, together with their potentially producing Fusarium species in wheat, barley, and maize in Tunisia. The high level of fumonisins in cereals, especially maize, stresses the importance of the control and the regularization of these mycotoxins for food safety.