Innovative approaches to the management of mycotoxin-producing fungi

Fusarium and Aspergillus pose significant challenges for agriculture and medicine due to their increasing resistance to synthetic fungicides. These fungi reduce crop yields and quality, in addition to producing dangerous mycotoxins. Furthermore, they may infect immunocompromised humans and exhibit invasive growth patterns. Therefore, it is critical to seek innovative and long-term solutions to limit the resistance of these fungi. The current study focused on the identification of natural fungicides and inhibitors of mycotoxin biosynthesis in Aspergillus and Fusarium fungi. Various approaches were tested, including the use of phenolic compounds, plant extracts, and microorganisms. Bioprospecting phenols and their potential for sustainable trichothecene and Fusarium growth control in wheat were documented by reviewing scientific literature. However, since phenol derivatization can enhance antifungal activity, we also investigated the changes in cinnamic acid structure via esterification and etherification, and thereby obtained derivatives with enhanced antifungal activity against Fusarium spp. of clinical and agricultural interest. Since plants contain phenolic compounds with the potential to inhibit mycotoxins, five Mediterranean aqueous plant extracts (i.e., chestnut flower, cistus, eucalyptus, orange peel) were tested for inhibition of Aspergillus carbonarius (Bainier) Thom. rot and ochratoxin A (OTA) biosynthesis in grape berries. This study also tested four Bacillus strains (AngB1, BV, F33 and 54) for their inhibitory effects on Fusarium culmorum (Wm.G. Smith) Sacc. in wheat. When applied as seed coating, all strains reduced foot and root rot symptoms in wheat (by 77 to 97%). Bacillus sp. BV proved to be the most efficient strain, and was further tested. It was sprayed onto wheat spikes in order to evaluate its inhibitory effect on Fusarium head blight and deoxynivalenol, and demonstrated an equally marked antifungal effect on F. culmorum and deoxynivalenol. Future research can build on the findings of this thesis, toward reconsideration of the use of synthetic fungicides, since the focus is now on controlling economically important pests via an integrated pest management approach.