Comparative metabolomics of three Ganoderma species reveals species-specific bitter compounds for quality evaluation and flavor characterization

Bitterness is a major sensory barrier limiting the application of Ganoderma species, yet the metabolic basis underlying interspecific bitterness differences remains poorly understood. This study integrated sensory evaluation, untargeted LC-MS-based metabolomics, weighted gene co-expression network analysis (WGCNA), and quantitative compositional analysis to systematically compare Ganoderma lucidum ( GL ), Ganoderma sinense ( GS ), and Ganoderma leucocontextum ( GLE ). Sensory evaluation revealed that bitterness serves as a key distinguishing attribute among the three species, with GS exhibiting significantly lower bitterness intensity. A total of 27 core bitter-related metabolites were identified, including ganoderic acids, bitter dipeptides, flavonoids, and alkaloids. WGCNA further confirmed the close association of these metabolites with bitterness. Quantitative analysis demonstrated that bitterness intensity was strongly correlated with the selective accumulation of specific ganoderic acid monomers rather than total triterpenoid content. KEGG pathway enrichment indicated that these bitter metabolites were primarily involved in amino acid metabolism, terpenoid backbone biosynthesis, and secondary metabolite biosynthesis pathways. Notably, the identified bitter-related ganoderic acids are also known to possess anti-inflammatory, immunomodulatory, and antitumor activities. These findings provide a metabolic framework for understanding bitterness differences among Ganoderma species and offer potential targets for quality control and flavor-oriented breeding strategies.