Improved Polysaccharide Production in Submerged Culture of Ganoderma lucidum by the Addition of Coixenolide

Abstract

Polysaccharides from Ganoderma lucidum have various bioactivities and have been widely used as nutraceuticals and functional foods. Coixenolide was added into the media to enhance the production of mycelia biomass and polysaccharides in the submerged culture of G. lucidum in this work. The results showed that when a level of 0.2% coixenolide was added at day 1, the biomass, exopolysaccharide, and intracellular polysaccharide reached 5.224, 0.222, and 0.399 g l(-1), respectively, which were 1.39-fold, 2.58-fold, and 2.24-fold compared to that of control. Analysis of the fermentation kinetics of G. lucidum suggested that glucose concentration in the coixenolide-added group decreased more quickly as compared to the control group from days 3 to 9 of the fermentation process, and the polysaccharides biosynthesis were promoted at the same culture period. However, the culture pH profile was not affected by the addition of coixenolide. Enzyme activities analysis indicated that coixenolide affected the synthesis level of phosphoglucose isomerase and α-phosphoglucomutase.

Bioactive Mushroom Polysaccharides: A Review on Monosaccharide Composition, Biosynthesis and Regulation

“…α-phosphoglucomutase (PGM; EC 5.4.2.2), a key enzyme in carbohydrate metabolism, catalyzes the reversible transfer of a phosphate group between C-1 and C-6. PGM converts Glc-6-P and Glc-1-P; Glc-6-phosphate enters a glycolysis pathway to yield energy, and Glc-1-phosphate is the precursor of sugar nucleotides (e.g., UDP-Glc, dTDP-Rha, UDP-Gal) in PSs [ 10 , 16 ]. In the study by Tang and Zhong, PGM activity was correlated with the amount of EPS produced by G. lucidum [ 71 ].…”

“…PGM gene overexpression in submerged culture resulted in increased PS production and upregulation of downstream genes encoding the enzymes involved in PS biosynthesis, including PGM, UDP-Glc pyrophosphorylase (UGP), and β-1,3-glucan synthase (GLS) [ 14 ]. PGM activity was also affected by the addition of coixenolide during PS production in G. lucidum [ 10 ]. In a submerged culture of C. militaris , PGM was the key enzyme for regulation of IPS biosynthesis [ 11 ].…”

“…Zhu et al found that higher UGP activity was correlated with higher IPS biosynthesis rate in Cordyceps militaris [ 11 ], suggesting an important role of UGP in PS biosynthesis. However, a controversial conclusion was found by Zhou et al, Wei et al, and Yang et al: that there was no significant association of UGP activity with PS biosynthesis [ 10 , 12 , 70 ], which may be attributed to the different strains and methods. Therefore, the exact reason still requires further research.…”

“…Enzyme activities of glucokinase (GK) [ 16 ], UDPG-dehydrogenase (UGDG) [ 11 ], and dTDP-Glc pyrophosphorylase (dTDP-GPP) [ 10 , 70 ] have also been investigated. However, these studies showed no notable association between PS biosynthesis and activities of these enzymes.…”

“…The biosynthetic pathways of PS involve synthesis of nucleotide sugar precursors, assembly of repeating monosaccharide units, and the polymerization process. In PS biosynthetic pathways, enzymes involved in the biosynthetic pathways of nucleotide sugar precursors are closely related with production of mushroom PSs [ 9 , 10 , 11 , 12 ]. In submerged culture of Ganoderma lucidum (lingzhi mushroom), overexpression of homologous α-phosphoglucomutase and uridine diphosphate glucose pyrophosphorylase (UDP-glucose pyrophosphorylase) genes enhanced PS production [ 13 , 14 ].…”