Effect of different colloidal gold nanomaterials on Ganoderma lingzhi fermentation for production of ganoderma polysaccharide and triterpenoid through macroscopic and microscopic investigation.

Ganoderma lingzhi (G. lingzhi) is a Basidiomycete macrofungus valued for its secondary metabolites with pharmacological activity. To enhance the biosynthesis of secondary metabolites, various exogenous additives have been introduced to fungal fermentation processes. Metal nanomaterials, while known to influence cellular metabolism in mammalian systems, exhibit unclear effects when applied to macrofungal cultivation systems. The study systematically evaluates the impact of three distinct gold nanostructures-nanoparticles (AuNPs), nanorods (AuNRs), and nanoclusters (AuNCs)-on bioactive metabolite production during G. lingzhi submerged fermentation, employing integrated macroscopic process analytics and microscopic characterization. The results demonstrate that their impact on mycelial growth and bioactive metabolite production varied with the type, concentration, and addition timing of gold nanomaterials. Microscopic survey on cell surface morphology and nanoparticle distribution also reveals the different patterns of nanomaterial-mycelia cell interaction. Under the optimized addition conditions, AuNPs increased total polysaccharide content by 50.37% compared to the control group, while AuNRs increased triterpenoid content by 42.78%. The work confirms the potential of colloidal gold nanomaterials to facilitate the submerged fermentation of G. lingzhi, which is expected to encourage the development of nanomaterial additives-based approach for efficient microbial bioactive substances production.