Comparative Nutritional and Antioxidant Profiling of the <i>Ganoderma lucidum</i> Complex: From Fruiting Bodies to Oleic Acid-Supplemented Fermentation

Ganoderma lucidum (G. lucidum), a traditional medicinal and edible fungus, exhibits significant differences in nutritional composition and antioxidant activity among its fruiting bodies, spore powders, and submerged fermentation products. This study compared the contents of polysaccharides and triterpenoids, as well as DPPH and hydroxyl radical scavenging activities, in fruiting bodies (caps and stipes), spore powders from different sources, and fermentation broths of five G. lucidum strains (FXLZ-02, FXLZ-05, FXLZ-07, FXLZ-08, and FXLZ-15). The results show that traditional products, especially spore powders, were rich in polysaccharides and triterpenoids, whereas certain fermentation broths exhibited stronger antioxidant activity, suggesting that the fermentation can selectively enrich functional components. To further improve fermentation efficiency, the regulatory effect of exogenous oleic acid (OA, 1%, v/v) was investigated. OA significantly promoted mycelial biomass accumulation, with a 77.5% increase in FXLZ-07, and shifted the synthesis peaks of exopolysaccharides (EPS) and triterpenoids forward to days 6–8. In strain FXLZ-08, EPS and triterpenoid yields reached 6.83 and 2.74 mg g–1, representing 1.86- and 2.15-fold increases over the control, respectively. Antioxidant responses were strain-specific: FXLZ-02 showed enhanced DPPH scavenging activity (nearly 90%, +18.3%) and hydroxyl radical scavenging activity (50%, +12.1%), while FXLZ-05 showed no significant improvement. In conclusion, oleic acid can serve as an effective elicitor to optimize G. lucidum fermentation, shorten the production cycle, and directionally enhance metabolite synthesis and antioxidant activity, providing a theoretical basis for the development of functional Ganoderma products.