Nutritional and Bioactive Properties of an Amazon Wild Oyster Culinary-Medicinal Mushroom, Pleurotus ostreatus (Agaricomycetes): Contributions to Functional Food and Human Health.

A wild Amazonian strain of Pleurotus ostreatus (Jacq.: Fr.) P. Kumm. was cultivated using local agroindustrial wastes-açai seeds (AS) and elephant grass straw (EGS)-as substrates and evaluated for its nutritional composition and bioactivities. Basidiomata presented higher contents of protein (27.19%) and dietary fiber (18.57%) when grown on AS, while lipids (2.26%), nonfiber carbohydrates (53.21%), and metabolizable energy (304.02 kcal/100 g) were higher on EGS substrate. Methanolic extracts of P. ostreatus grown on AS also provided a higher phenolic content (31.24 mg gallic acid equivalents/g extract) and greater antioxidant activity, scavenging 82.60% and 91.13% of DPPH· and ABTS·+ radicals, respectively, while chelating ability of Fe2+ was higher on EGS mushroom extracts (74.34%). Hemagglutinating activity of 1,997 HA U/mg protein was observed solely in the aqueous extracts of AS-grown mushrooms. Higher proteolytic activity was observed in aqueous extracts from mushrooms grown on EGS (219.10 U/mg protein), and their saline extract was the sole one with fibrinolytic activity (3.14 mm2). Both substrates and extractions yielded similar activity of protease inhibitors, with higher inhibition of serine than cysteine proteases. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis profiling showed protein bands related to lectins, proteases, fibrinolytic enzymes, and protease inhibitors. Thus, this wild Amazonian strain has great nutritional potential and produces biomolecules that can contribute to important applications in food, health, and industry.