Avaliação da atividade antifúngica do extrato de Aspergillus nomiae frente ao fitopatógeno do melão amarelo Fusarium jinanense

Abstract

Brazil has a climate that is highly favorable for fruit cultivation, with melon (Cucumis melo L.) standing out as the Brazilian fruit with the largest share of production aimed at export. However, the occurrence of post-harvest diseases has caused significant economic losses, as it compromises the fruit's quality and commercial viability. Among these issues, the main phytopathology affecting melons is "stem-end rot" or "fusarium rot," caused by fungi of the genus Fusarium. Currently, the most widely used control method is the application of synthetic fungicides. However, there has been a growing interest in less environmentally harmful alternatives, such as natural products. In this regard, secondary metabolites produced by endophytic microorganisms have emerged as a promising alternative. Thus, the objective of this study was to evaluate the antifungal activity of the endophytic fungus Aspergillus nomiae (bM-03), cultivated in Czapek Agar (CZA) medium, against the phytopathogen Fusarium jinanense (UFCM-0611), using the co-culture technique. In addition, the chemical profile of the ethyl acetate extract of A. nomiae was analyzed using proton nuclear magnetic resonance (NMR) spectroscopy. Fungi bM-03 and UFCM-0611 were inoculated in a co-culture system for periods of 14 and 21 days, in quadruplicate, using Czapek Agar medium. Ethyl acetate extracts of bM-03 were subjected to antifungal testing, employing five treatment concentrations (0.050, 0.100, 0.150, 0.250, and 0.350 mg/mL). After a 24- hour incubation period at 25 °C, the percentage of mycelial growth inhibition (%MGI) was calculated. The 21-day extract of bM-03, at a concentration of 0.350 mg/mL, was able to reduce the mycelial growth of UFCM-0611 by 50.16% (±4.10). The present work is one of the first records of the antifungal activity of A. nomiae and the first with anti F. jinanense activity. ¹H NMR analyses indicated an increase in the concentration of some secondary metabolites when comparing the monoculture profile with that of the co-culture. Thus, this study demonstrates that the co-culture technique in Czapek Agar can be a viable alternative for the production of metabolites with antifungal activity against Fusarium jinanense.