Identification and Nutrient Composition of a Wild Pleurotus pulmonarius Strain from Tibet, and the Antioxidant and Cytotoxic Activities of Polysaccharides from This Fungus

The selection and breeding of high-quality wild edible fungal strains can bring significant economic and social benefits. A wild fungal strain (X21185) from the Tibetan Plateau was isolated and identified as a novel <i>Pleurotus pulmonarius</i> (<i>P. pulmonarius</i>) based on its morphological and molecular characteristics. The appropriate culture conditions for <i>P. pulmonarius</i> were determined. The nutrient contents of <i>P. pulmonarius</i> fruiting bodies were analyzed. Compared with the conventional nutritional contents of the representative edible fungi (<i>Pleurotus ostreatu</i> and <i>Pleurotus eryngii</i>) and egg, the protein, ash, and dietary fiber contents of <i>P. pulmonarius</i> were higher. Four types of essential amino acids, seven types of nonessential amino acids, the total essential and nonessential amino acids of <i>P. pulmonarius</i> were present in considerably higher quantities than those of representative edible fungi (<i>Pleurotus ostreatus</i> and <i>Pleurotus citrinopileatus</i>) and egg, respectively. <i>P. pulmonarius</i> polysaccharides (PPPs) had strong ABTS⁺, DPPH, and hydroxyl free radical scavenging activities (EC₅₀: 0.051, 3.322, and 2.87 mg/mL, respectively), and the cytotoxicity was higher against HepG2 hepatocellular carcinoma cells (IC₅₀: 1.501 mg/mL) than against MDA-MB-468 triple-negative breast cancer cells (IC₅₀: 2.183 mg/mL). This study provides a foundation for the development of the novel wild <i>P. pulmonarius</i> strain.