ZnO-Nanoparticles as antifungal agent limiting growth and mycotoxins production by Aspergillus flavus and Fusarium proliferatum on a maize based-medium

GABRIELA PENA; MATIAS CARDENAS; GABRIEL PLANES; CESAR BARBERO; LILIA CAVAGLIERI; SOFIA CHULZE

San Juan

Congreso; ICM 11 International Mycological Congress; 2018

ZnO-Nanoparticles as antifungal agent limiting growth and mycotoxins production by Aspergillus flavus and Fusarium proliferatum on a maize based-mediumGabriela A. Pena1, Matias Cárdenas1, Gabriel A. Planes2, César A. Barbero2, Lilia R. Cavaglieri1, Sofía N. Chulze1.1Mycology. Department of Microbiology and Immunology, Faculty of Physical-Chemical and Natural Sciences, National University of Rio Cuarto, Cordoba, Argentina. 2 Group of advanced materials. Department of Chemistry, Faculty of Physical-Chemical and Natural Sciences, National University of Rio Cuarto, Cordoba, Argentina.Emails: 1gpena@exa.unrc.edu.ar, maty.c316@gmail.com, 2gplanes@exa.unrc.edu.ar, 2cbarbero@exa.unrc.edu.ar, 1lcavaglieri@exa.unrc.edu.ar, 1schulze@exa.unrc.edu.ar.In Argentina, around 60% of maize is exported and the remaining is used as feedstuff. Aspergillus flavus and Fusarium proliferatum are two mycotoxigenic species frequently isolated from maize that produce aflatoxins and fumonisins, respectively. ZnO-Nanoparticles (ZnO-NPs) have been used as efficient antimicrobial agents. ZnO is a non toxic compound and a strategy of low cost and low environmental impact to reduce mycotoxin accumulation in stored maize. The aims of this study were: (i) to synthesize and characterize ZnO-NPs; (ii) to evaluate their effect under presence/absence of white light during fungal incubation on growth rates and aflatoxin B1 (AFB1) and fumonisin B1 (FB1) accumulation by A. flavus and F. proliferatum, respectively, and (iii) to determine fungal morphological alterations by SEM. ZnO-NPs were synthesized according to the drop by drop mixing method and characterized by SEM. Aspergillus flavus RCAF016 and F. proliferatum ITEM 15699 strains were grown on a 2% maize based medium (0.995 aW) containing 0, 10, 50 and 100 mM ZnO-NPs. The inoculated plates (by triplicate) were incubated at 25°C, 21 days in darkness or under 12/12 h photoperiod cold white and black fluorescent lamps. SEM analysis of ZnO-NPs showed thin flakes of 200 × 200 nm and thickness of ~30 nm. Aspergillus flavus and F. proliferatum strains were able to grow in presence of 0, 10, 50 and 100 mM ZnO-NPs. However, growth rates were reduced (in relation to the control) at the three concentrations evaluated under photoperiod or darkness incubation conditions. Hypha and conidia morphological alterations were observed in both A. flavus and F. proliferatum treated with ZnO-NPs by SEM analysis (2000-5000 X). The alterations were: hyphal deformations, less conidiation and unusual bulges. Mycotoxin accumulation was also affected by the ZnO-NP treatments. After 3 days of incubation in darkness and 10 mM ZnO-NPs, Aspergillus flavus RCAF016 showed AFB1 production higher than the control, but at 50 and 100 mM the toxin production was inhibited at not detectable (ND) levels. After 7 and 14 days, AFB1 was reduced at ND levels at 10, 50 and 100 mM ZnO-NPs, whereas, at 21 days the toxin was reduced by 85% and at ND levels at 50 mM and 100 mM, respectively. Under the photoperiod incubation condition AFB1 was not detected in both controls and treatments. Fumonisin B1 accumulation by F. proliferatum ITEM 15699 was also reduced by ZnO-NP treatments. Both incubations conditions showed reduction in FB1, in general, at the three ZnO-NPs concentrations evaluated. The reduction was between 73 and 99% after 14 and 21 days of incubation. This study showed that ZnO-NPs could be used for limiting growth and AFB1 and FB1 accumulation by A. flavus and F. proliferatum, respectively in a maize based medium. This environmental friendly strategy of low cost could be applied during maize storage.