Resumo

Several strategies have been used to eliminate toxigenic fungi FBs producer in grains. Fusarium verticillioides can be controlled by synthetic fungicides application in the field or storage. However, that treatment can be problematic due to high toxicity to mammals and due to residuals, which may remain in the foods. On the other hand, inorganic compounds as zinc (Zn) are of low cost, stable and present strong antibacterial activity. In addition, of them are utilized as dietary supplements and authorized for the food fortification. Considering the Zn-compounds advantages regarding (a)effectiveness, safety & stability on antibacterial activity at low Zn concentrations; (b) lack of information of those compounds (including at nanoparticles-NPs sizes) antifungal properties; (c) need of effective control & prevention methods against toxigenic F. verticillioides for field crops application; this work reports an evaluation of Zn-compounds (ZnSO₄, Zn(ClO₄)₂, ZnO, ZnO-NPs) treatments on toxigenic F. verticillioides behavior regarding: antifungal (colony growth inhibition) & possible antitoxin (FBs reduction) properties. Apart from conidia production and hyphae alterations (cell mortality and reactive oxygen species-ROS-cell formation) by scanning electron, light and confocal optical microscopies were evaluated. From the data obtained on the Zn anti-fungal/FBs properties, F. verticillioides conidia production and hyphae alterations of all treatments depending on the concentration applied inhibited fungus growth and FBs formation of same extent. All treatment significantly reduced the fungi growth (Group Control: 45-49.5) in the highest concentration (100 mM: no growth/18.3/19 and 14.5 mm for Zn(ClO₄)₂/ZnSO₄/ZnO and ZnO-NPs, furthermore 100% FBs production reduction with Zn(ClO₄)₂/ZnSO₄ and ZnO-NPs treatments(Control: 554 µg/kg). They also caused hyphae morphological alterations (deformed and/or broken) leading to mortality and ROS production, in different proportions though. The action of Zn-compounds treatment can be due to morphological and metabolic changes during the fungi structure formation. Data suggest that Zn-compounds could be further utilized as an effective fungicide in agricultural crops and for food safety applications against field fungi (F. verticillioides) - especially ZnSO₄ that presented the highest antifungal activity and has already been authorized for foods fortification application: thus safe and non toxic for humans and animals, in adequate amounts.