Avaliação da potencial atividade antifúngica de extratos de substratos gastos de cogumelo Pleurotus spp. sobre Aspergillus flavus.

Abstract

The cultivation of edible mushrooms has gained prominence due to their nutritional and medicinal properties. The genus Pleurotus stands out because it has the ability to degrade lignocellulosic residues that are very common in agricultural waste. The material resulting from mushroom cultivation is known as spent post-mushroom cultivation substrate or Spent Mushroom Substrate (SMS), which can be useful from a biotechnological point of view. The search for antifungal products to control Aspergillus flavus and the reuse of SMS represents a biotechnological association that has not yet been properly explored. Thus, the objective was to produce, chemically characterize and evaluate the antifungal potential of extracts from the substrate spent on 100% banana leaves resulting from the cultivation of P. djamor (SGPd) and P. ostreatus (SGPo) mushrooms. The hydroalcoholic extracts of SGPd and SGPo were produced with 2g of substrate with 50 mL of ethanol/water solution (70:30 v/v). Natural product composition of the extracts was performed to detect total phenolics and flavonoids. The antifungal activity was carried out against mycotoxin-producing strains from the mycotheque “Colección de Cultivos de Microorganismos de la Universidad Nacional de Asunción” – Paraguay. The lowest MIC, CFM, MIC/CFM ratio, inhibition of conidial germination in broth and mycelial growth on solid media (radial growth) were determined. Carboxin (CBX) was used as a positive control. Total phenolic values in the extracts ranged from 12.04 μg EAG/mL to 24.60 μg EAG/mL, respectively in SGPd and SGPo. As for total flavonoids, the SGPd and SGPo results obtained ranged from 5.67 μg EQ/mL to 6.55 μg EQ/mL, respectively. The drugs under study showed antifungal activity against A. flavus, showing effects from 1024 μg/mL. The SGPo proved to be more promising, since, of the 6 strains tested, 5 were inhibited at 1024 μg/mL. SGPd, SGPo and CBX inhibited the germination of AS35 conidia (p<0.05). Considering the time and differences in efficacy of the test drugs, SGPd, SGPo and CBX were able to reduce the mycelial growth of strains AS35 and AS118. Therefore, the use of SGPd and SGPo to control fungal growth and food preservation is a promising sustainable alternative. In the present work, SGPd and SGPo revealed their antifungal potential against the A. flavus strains tested.