Abstract

Ganoderma leucocontextum, a fungus discovered by our group, is highly valued for its immune modulation and anti-tumor polysaccharides significantly. Thus, this research aims to select a substrate formulation to enhance its polysaccharides and reveal the underlying mechanism. Seven distinct substrate formulations, incorporating combinations of fruit-tree wood, bagasse, oak wood, and cottonseed hulls, were explored. Interesting, the fruiting bodies grown on GMTZ fruit-tree wood–bagasse formulation showed the highest polysaccharide content at 3.19 ± 0.56% (p < 0.01 or 0.05). Moreover, GMTZ efficiently channeled resources toward diterpenoids synthesis at the expense of flavonoid and most triterpenoid production. It also dramatically enhanced androgen synthesis, while showing no corresponding accumulation of storage lipids or certain hormone signals, reinforcing a specific metabolic commitment. Furthermore, PCA analysis of the metabolomics confirmed the profound impact of substrate formulations. Correlation analysis revealed that GMTZ promoted a growth-and-synthesis metabolic phenotype, which was characterized by metabolic signatures of supporting anabolism and cellular homeostasis. In contrast, formulations that induced the defense-and-stress phenotype were often rich in lignin, which diverted resources toward detoxification and stress responses and suppressed growth-oriented metabolite synthesis. Moreover, prostaglandin A1, deoxycholic acid, cucurbitacin E, and 1-hydroxy-2-naphthoic acid were found to be positively correlated with polysaccharide synthesis. In addition, networks for polysaccharide biosynthesis were mapped and it was proposed, accordingly, that prostaglandin A1-phosphoglucomutase may be a mechanism by which GMTZ enhances polysaccharides. This research provided a substrate formulation for elevating polysaccharides in G. leucocontextum.

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