Enhanced Production and Profiling of Ganoderic Acids in Ganoderma lucidum Mycelia via Two-Stage Cultivation and GNPS-Guided Metabolomics

Ganoderic acids (GAs) are bioactive lanostane-type triterpenoids produced by Ganoderma lucidum that accumulate predominantly in fruiting bodies, whose long cultivation period limits their practical production. Using Global Natural Products Social Molecular Networking (GNPS), we identified G. lucidum TM701, which accumulated 99 GA derivatives in mycelia and exhibited higher triterpenoid levels and greater chemical diversity than the commercial strain BCRC 36203. Four abundant GAs (GA-Mb/Mc, GA-S/Mf, GA-T, and GA-R) were selected as marker compounds for monitoring GA production. A modified two-stage cultivation strategy, combining submerged inoculum preparation with nutrient optimization during static cultivation, increased GA production to 1396 mg L−1 GAs in potato dextrose broth supplemented with 2% glucose. Heat treatment revealed interconversion among GA-Mb/Mc, GA-Mh, and GA-P/Q, indicating a dehydration-driven stabilization of conjugated diene structures. G. lucidum TM701 mycelia not only provide a platform for triterpenoid production, but also serve as a promising model for elucidating GA biosynthesis and investigating their thermal transformation.