Antimicrobial activity of zinc, copper and silver nanoparticles against fungal pathogens

BAIGORRIA, C; DEBES, MA; CERIONI, L; TIRADO, M; LEDESMA, A; RAPISARDA, VA; VOLENTINI, SI

Congreso; LVIII Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research; 2022

SAIB

The main economic losses for the lemon fruit production in Tucumán are due to postharvest fungal diseases. In order to control them, chemical fungicides are used, carrying a high risk to environmental health and increasing the appearance of resistant isolates. For this reason, the need to investigate and develop alternative methods for the control of resistant pathogens becomes evident. A promising option is represented by metal ion nanoparticles, with recognized antimicrobial action. In the present work nanoparticles of zinc oxide, silver or copper oxide (ZnO-Np, Ag-Np, CuO-Np) were synthesized and evaluated to control local isolates of fungicide resistant phytopathogens. The nanoparticles were obtained by chemical or green synthesis and were characterized in respect to their morphology and size. The antifungal activity was tested in vitro using conidial suspensions adjusted to 106 UFC/ml of Penicillium digitatum, Penicillium italicum, sensitive or resistant to fungicides. The obtained results show that ZnONp did not significantly inhibit the development of pathogens up to a concentration of 40 mg/ml. The CuO-NP were effective against P. digitatum with a MFC (minimum fungicidal concentration) of 50 mg/ml, while for P. Italicum the MFC was 100 mg/ml. The Ag-Np showed the highest antifungal activity with a MFC 10 μg/ml for all pathogens. At lower concentration, 1µg/ml Ag-Np was able to inhibit conidial germination. Additionally, as a first step to characterize the mechanism of action, it was observed that Ag-Np increase in the conidial membrane permeability for all the pathogens tested by fluorescent probe SYTOX Green. The resistant isolates exhibited similar behaviors to their wild type. Ours results represent the first findings in the evaluation of metallic nanoparticles as alternative antifungals for the control of relevant phytopathoges that affect the lemon production in our region.