Antioxidant and antibacterial activity of extracts obtained from Pleurotus ostreatus mycelium cultivated with agro-industrial residues

Abstract

Background and Aims: Pleurotus ostreatus (PO) is an edible mushroom whose consumption has increased due to its important nutrient content. It is a saprophytic fungus that can acquire nutrients depending on the substrate in which it is grown, and it is well-known that agro-industrial residues are an important source of nutrients. This work aims to evaluate the effect of spent coffee grounds (SCG) and potato peel residues (PPR) as a substrate on the polyphenol content and antioxidant and antibacterial activity of hydroalcoholic extract from PO mycelium. Methods: PO cultivation was carried out with four substrates that included wheat straw substituted with 10, 15, and 20% of a 1:1 mixture of residues (SCG and PPR). From the mycelium obtained, hydroalcoholic extracts were generated in which the phenolic content, antioxidant (antiradical and reducing power activity), and antibacterial activity against foodborne pathogens (Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella typhimurium) were determined. Key results: The results showed that the highest antiradical activity against DPPH and the quantification of phenols occurred in the substrate with 10, 15, and 20% of SCG and PPR; the substrate containing 20% had a higher content of flavonoids and ABTS antiradical activity. However, there were no differences in the chlorogenic acid content among any substrates. All the substrates also exhibited antibacterial activity against tested pathogens, mainly against S. aureus. Conclusions: SCG and PPR enhance the polyphenol content and antioxidant and antimicrobial activity of hydroalcoholic extract from PO mycelium, making them effective substrates for cultivation.