The Liquid-Fermentation Formulation of Sanghuangporus sanghuang Optimized by Response Surface Methodology and Evaluation of Biological Activity of Extracellular Polysaccharides

Abstract

Sanghuangporus sanghuang is a rare fungus growing on mulberry trees that has immense medicinal value. This study aimed to optimize the liquid-fermentation-media formulation and culture conditions for large-scale culturing of S. sanghuang by performing one-way testing and response surface methodology. The antioxidant and anticancer activities of the extracellular polysaccharides from S. sanghuang were also analyzed. The optimal formulation and growth conditions for S. sanghuang were as follows: glucose, 30.2 ± 0.37 g/L; yeast extract, 14.60 ± 0.05 g/L; dandelion powder, 1.24 ± 0.01 g/L; shaker speed, 150 r/min; and temperature, 25 °C. We obtained 13.99 ± 0.42 g/L of mycelium biomass by culturing S. sanghuang for 15 days with the optimized formulation. This was 2-fold higher than the mycelial mass obtained with the sub-optimal formulation. The extracellular fungal polysaccharides showed significant antioxidant activity against ABTS and DPPH free radicals, and significantly reduced the in vitro growth and survival of several cancer cell lines. The anticancer activity of the extracellular fungal polysaccharides was significantly higher in the human glioma cells than in other cancer cell lines. In summary, this study optimized the liquid media formulation and conditions for the large-scale culturing of S. sanghuang. Furthermore, the extracellular polysaccharides from S. sanghuang showed significant antioxidant and anticancer activities.

Keywords: Sanghuangporus sanghuang; biological activity; extracellular polysaccharides; response surface optimization.

Figure 1

The effects of different carbon sources on the growth of strains of S. sanghuang. (A) MS-1, (B) MS-3, and (C) MS-7. Note: ** represents p < 0.01 for comparisons with the CK group; ^## represents p < 0.01 for comparisons with the optimal carbon source.

Figure 2

The effects of different nitrogen sources on the growth of S. sanghuang. (A) MS-1; (B) MS-3; (C) MS-7. Note: * represents p < 0.05 and ** represents p < 0.01 for comparisons with the CK group; ^## represents p < 0.01 for comparisons with the optimal nitrogen source.

Figure 3

The effects of different concentrations of glucose on the growth of S. sanghuang. The mycelial biomasses of (A) MS-1; (B) MS-3; and (C) MS-7. (D) Fermentation liquid media with different glucose concentrations for growing MS-1, MS-3, and MS-7 strains of S. sanghuang. Note: * represents p < 0.05 and ** represents p < 0.01 when compared with the previous group.

Figure 4

The effects of different yeast extract concentrations on the growth of S. sanghuang. The mycelial biomasses of (A) MS-1; (B) MS-3; and (C) MS-7 strains of S. sanghuang. (D) Fermentation liquid media with different yeast extract concentrations for growing MS-1, MS-3, and MS-7 strains of S. sanghuang. Note: * represents p < 0.05 and ** represents p < 0.01 compared with the previous group.

Figure 5

The effects of dandelion powder on the growth of strains of S. sanghuang. (A) MS-1; (B) MS-3; (C) MS-7. Note: * represents p < 0.05 and ** represents p < 0.01 compared with the CK group.

Figure 6

Response surface stereograms based on the Box–Behnken design for the optimization of liquid-fermentation-media components for growing S. sanghuang. ((A1–A3)–(C1–C3)) Corresponding contour values. (D1–D3) Interactions between different concentrations of carbon and nitrogen sources. (E1–E3) Interactions between different concentrations of the carbon source and the dandelion powder. (F1–F3) Interactions between different concentrations of the nitrogen source and the dandelion powder.

Figure 7

Validation of the optimized liquid fermentation formulation for growing S. sanghuang. (A) The CK group (PDB) and optimized-fermentation-liquid-growth formulations for S. sanghuang. (B) The mycelial biomass for the MS-1, MS-3, and MS-7 strains of S. sanghuang with the control and optimized formulations. Note: ** represents p < 0.01 compared with the CK (PDB) group.

Figure 8

Antioxidant activities of the polysaccharides extracted from S. sanghuang. (A) ABTS-radical scavenging capacity of S. sanghuang. (B) DPPH radical scavenging capacity of the polysaccharides extracted from S. sanghuang. (C) FRAP assay results show the total antioxidant capacity of the polysaccharides extracted from S. sanghuang.

Figure 9

MTT assay results show the effects of the polysaccharides extracted from S. sanghuang on the growth of various cancer cells.