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

BAIGORRIA CARINA G; DEBES, MARIO ; CERIONI LUCIANA; TIRADO MONICA ; LEDESMA ANA; RAPISARDA VIVIANA A; VOLENTINI SABRINA I

Mendoza

Congreso; Congreso SAIB 2022; 2022

The main economic losses for the citrus fruit production in Tucumán are due to postharvest fungal diseases. Chemical fungicides are used to control them, but they carry a high risk to environmental health and increase 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. For this reason, in the present work we synthesized and evaluated nanoparticles of zinc oxide, silver or copper oxide (Np-ZnO, Np-Ag, Np-CuO) to control local phytopathogens isolates resistant to fungicides. The nanoparticles were obtained by chemical synthesis or green synthesis and were characterized in respect to morphology and size. The antifungal activity was tested in vitro using conidial suspensions adjusted to 106 UFC/ml of Penicillium digitatum, P. Italicum, sensitive or resistant to fungicides, and Geotrichum citri-aurantii. The results obtained showed that Np-ZnO did not significantly inhibit the development of pathogens up to a concentration of 40 mg/ml. The NP-CuO 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. G. citri-aurantii was the most sensitive, with a MFC of 1 mg/ml. The Np-Ag showed the highest antifungal activity with a MFC 10 μg/ml for all pathogens. At lower concentration,1µg/ml Np-Ag were able to inhibit conidial germination. On the other hand, using the fluorescent probe sytox-green, we demonstrated that Np-Ag mechanism of action would be mediated by an increase in the conidial membrane permeability for all the pathogens tested. The resistant isolates showed behaviors similar to their wild type isolates. These results represent the first findings in the study of metallic nanoparticles as alternative antifungals for the control of relevant phytopathogenic fungi in the citrus production in our region.