Optimization of Triterpene Yield from Ganoderma atrum HBSD Z19 (Agaricomycetes) by Optimization of Medium Components and Evaluation of Bioactivity Under Simulated Gastrointestinal Digestion In Vitro.

The intracellular triterpene yield from Ganoderma atrum was enhanced by optimization based on single-factor experiments, Plackett-Burman experimental design (PBED) and response surface methodology (RSM) under liquid fermentation conditions. The optimal medium composition (g·L-1) was glucose (46.0), bean cake powder (30.2), KH2PO4 (2.0), CaCl2 (3.0), MgSO4 (1.5), FeSO4 (0.2), and pH 6.0. Under the optimal conditions, the highest triterpene yield of 0.527 g·L-1 was obtained, which was 4.705-fold higher than before optimization. The fermented powder that was collected from the optimal medium was subjected to simulated gastrointestinal digestion, with differences resulting from extraction in different digestive juices (purified water, simulated gastric digestive juice, simulated gastrointestinal digestive juice). The content of triterpenes and polysaccharides increased, except for total phenol content. In terms of the antioxidant activity, the 1,1-diphenyl-2-picrylhydrazyl radical 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl (DPPH+⋅) scavenging activity gradually decreased whereas the 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+⋅) scavenging activity first decreased and then increased. In terms of enzyme viability, the activity of α-amylase (α-AL) and α-glucosidase (α-GC) in the digestive juices decreased dramatically. The main bioactive components of G. atrum and their bioactivity in digestive juices were evaluated, providing a reference for the effective use of fermented power from G. atrum.

Optimisation of the production of a selenium-enriched polysaccharide from Cordyceps cicadae S1 and its structure and antioxidant activity.

The fermentation medium of a newly identified Cordyceps cicadae S1 was optimized by response surface methodology, with the optimal medium containing sucrose (80 g/L), yeast powder (60 g/L), KH2PO4 (5 g/L), MgSO4·7H2O (1 g/L) and Na2SeO3 (0. 1 g/L). Under these conditions, the extracellular polysaccharide yield was 8.09 g/L. A novel selenium-enriched polysaccharide (PACI-1) was isolated from Cordyceps cicadae, purified and identified as a homofructose polysaccharide with a low average molecular weight of 9.95 × 103 Da. The fine structure of PACI-1 was analyzed using NMR, CD, and AFM. Additionally, the in vitro antioxidant results showed that the PACI-1 had stronger antioxidant capacity than natural polysaccharides. These results provided a candidate strain for producing selenium polysaccharide and a new polysaccharide from C. cicadae, which showed good antioxidant activity.