Effect of alkali-treated birch sawdust on the lignocellulase secretion and exo-polysaccharide production by Inonotus obliquus under submerged fermentation and its lignocellulose degradation patterns

Necessity of Different Lignocellulose on Exopolysaccharide Synthesis and Its Hypoglycemic Activity In Vitro of Inonotus obliquus

Current work proposes elm sawdust, poplar sawdust, pine sawdust, and cotton straw with different lignocellulose compositions and structures as the research objects to investigate the relationship between the hypoglycemic activity of mycelium polysaccharides from Inonotus obliquus and lignocellulose biodegradation. Four kinds of lignocellulosic materials could significantly increase the exopolysaccharide content and α-glucosidase inhibition rate and advance the occurrence time of α-glucosidase inhibition activity. Among all groups, the polysaccharide synthesis promotion effect of the cotton straw group was the best, which exopolysaccharide yield was 92.05% higher than that of the control group after 11-day fermentation. Meanwhile, the highest α-glucosidase inhibitory activity was found in the elm sawdust group on the 11th day (30.99%, which was 137.47% higher than control), and the exopolysaccharide in the elm sawdust group showed its effectiveness on glucose consumption of insulin resistant HepG2 cells at the concentration of 20 µg/mL, significantly higher than that of the metformin group (P < 0.05). The cellulose in the non-crystalline region of elm and pine and the hemicellulose of poplar were mainly used in the fermentation of I. obliquus, while the cellulose in the crystalline zone and amorphous zone of cotton straw was degraded to improve the exopolysaccharide content of I. obliquus. This paper revealed the necessity of different kinds of lignocellulose for the synthesis of active polysaccharide from I. obliquus and provided a new idea for the regulation of polysaccharide synthesis pathway.

Improved production and antioxidant activity of exopolysaccharides by submerged culture of Lentinula edodes by the addition of lignocellulose

The objective of this study was to investigate the effect of addition of four different lignocellulose (water-treated corn straw, water-treated xylosma sawdust, alkali-treated corn straw and alkali-treated xylosma sawdust) on the production and antioxidant activity of exopolysaccharides by Lentinula edodes. To evaluate the antioxidant activity of polysaccharides, the analyses of 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging activity, lipid peroxidation inhibition rate and erythrocyte hemolysis inhibition rate were carried out. The result clearly indicated that the exo-polysaccharide production and antioxidant activity by L. edodes mycelium was enhanced in varying degrees via the decomposition of lignocellulose. The yield of exo-polysaccharide in alkali-treated corn straw group was the highest (0.351 g/L), which was 31.06% higher than that in control group after 5 days of submerged fermentation. High DPPH radical scavenging activity was observed in water-treated xylosma sawdust group, which decreased with the extension of fermentation time (23.15%-44.06%). Alkali-treated groups performed better than water-treated groups in terms of lipid peroxidation inhibitory activity. As for hemolysis inhibition activity toward erythrocytes, xylosma sawdust groups showed stronger oxidation resistance than corn straw groups.