Composition analysis and prebiotics properties of polysaccharides extracted from Lepista sordida submerged cultivation mycelium

Abstract

In this paper, Lepista sordida polysaccharides (LSP) were separated from Lepista sordida (L. sordida) mainly using the Ultrasonic-Micro Wave Synergy Extraction (UMSE) method and purified by graded alcohol precipitation. Three polysaccharide components: 40%-LSP-UMSE, 60%-LSP-UMSE, and 80%-LSP-UMSE were obtained and further analyzed the physicochemical properties, structural characteristics, and antioxidant activity. And the effects on the proliferation of Lactobacillus casei of three polysaccharide components were studied. The characteristic absorption peaks and the β-glycosidic bond of three polysaccharide components were the direct expression at UV 200 nm using UV and FT-IR spectroscopy. The three polysaccharide components were mainly composed of glucose, mannose, galactose, and ribose using high-performance liquid chromatography (HPLC) analysis. The antioxidant activity study revealed that the polysaccharides obtained by the UMSE method had better antioxidant activity compared to the traditional "Hot Water Extraction (HWE)" method. In addition, the polysaccharide components promoted the proliferation of L. casei to some extent. 40%-LSP-UMSE, 80%-LSP-UMSE as the carbon source had better acid production than the control inulin. Three LSP-UMSE used as a carbon source compared with glucose for culturing L. casei could significantly improve its tolerance to bile salts. Results are helpful to develop the bioactive polysaccharides from Lepista sordida and beneficial to develop a unique health and functional product in the future.

Keywords: Lepista sordida polysaccharides; antioxidant; monosaccharide composition; prebiotics; ultrasonic-micro wave synergy extraction method.

Figure 1

Molecular weight analysis of LPS. (A) 40%-LSP-UMSE, (B) 60%-LSP-UMSE, (C) 80%-LSP-UMSE.

Figure 2

HPLC chromatogram of standard monosaccharide and LSP-UMSE (A) standard monosaccharide, (B) 40%-LSP-UMSE, (C) 60%-LSP-UMSE, (D) 80%-LSP-UMSE.

Figure 3

Spectral analysis of 40%-LSP-UMSE, 60%-LSP-UMSE and 80%-LSP-UMSE. (A) UV scanning spectra of 40%-LSP-UMSE, 60%-LSP-UMSE and 80%-LSP-UMSE; (B) FT-IR spectra of 40%-LSP-UMSE, 60%-LSP-UMSE and 80%-LSP-UMSE.

Figure 4

Scavenging ability of LSP-UMSE and LSP-HWE against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. Each value is expressed as mean ± SEM (n = 3).

Figure 5

Scavenging ability of LSP-UMSE and LSP-HWE on OH scavenging ability. Each value is expressed as mean ± SEM (n = 3).

Figure 6

Scavenging ability of LSP-UMSE and LSP-HWE against ABTS radicals scavenging ability. Each value is expressed as mean ± SEM (n = 3).

Figure 7

LSP-UMSE and LSP-HWE for ferric ion chelating activity. Each value is expressed as mean ± SEM (n = 3).

Figure 8

Optimal concentration for 24 h incubation (Note: 0% was used as control, * was significantly p < 0.05, ** was extremely significantly p < 0.01).

Figure 9

Growth curves of L. casei cultured at different carbon source concentrations and acidity values after 24 h incubation at different carbon source concentrations. (A) Glucose carbon source; (B) inulin carbon source; (C) 40%-LSP-UMSE carbon source; (D) 60%-LSP-UMSE carbon source; (E) 80%-LSP-UMSE carbon source; (F) acidity comparison of different carbon source concentrations at 24 h (Note: 0 mg/ml was used as control, * was significantly p < 0.05, ** was extremely significantly p < 0.01).

Figure 10

(A) Growth promotion curve of 0.5% complex polysaccharide (monosaccharide: polysaccharides = 9:1) MRS; (B) OD₆₀₀ of 0.5% complex polysaccharide (monosaccharide: polysaccharide = 9:1) MRS culture. (Note: inulin was used as control, * was significantly p < 0.05; when glucose was used as control, # was significantly p < 0.05.)

Figure 11

(A) Comparison of acidity of 0.5% polysaccharides (glucose: polysaccharide =9:1) MRS medium at 24 h. (B) Bile salt tolerance of L. casei cultured with different carbon sources. (Note: inulin was used as control, *** was extremely significantly p < 0.005; when glucose was used as control, # was significantly p < 0.05; ### is extremely significant, p < 0.005).