Chemical structural and chain conformational characterization of some bioactive polysaccharides isolated from natural sources

Ganoderma lucidum is a wood-degrading basidiomycete with numerous pharmacological effects. Since the mushroom is very rare in nature, artificial cultivation of fruiting bodies has been known on wood logs and on sawdust in plastic bags or bottles. Biotechnological cultivation of G. lucidum mycelia in bioreactors has also been established, both on solid substrates and in liquid media by submerged cultivation of fungal biomass. The most important pharmacologically active constituents of G. lucidum are triterpenoids and polysaccharides. Triterpenoids have been reported to posses hepatoprotective, anti-hypertensive, hypocholesterolemic and anti-histaminic effects, anti-tumor and anti-engiogenic activity, effects on platelet aggregation and complement inhibition. Polysaccharides, especially β-d-glucans, have been known to possess anti-tumor effects through immunomodulation and anti-angiogenesis. In addition, polysaccharides have a protective effect against free radicals and reduce cell damage caused by mutagens.

Ganoderma lucidum and its pharmaceutically active compounds

Secondary metabolites from Ganoderma

The objective of this paper is to review the natural products and the pharmacological functions of Ganodermataceae family. Presently, studies on the bioactive components of Lingzhi are focused on polysaccharides and triterpenes/triterpenoids compounds. New Ganoderma polysaccharides, including their molecular weights, glycosyl residue compositions, glycosyl linkage and branches, are summarized in this paper. Also presented are new types of triterpenes and their characteristics from Lingzhi. Taking Ganoderma lucidum as an example, we reviewed its pharmacological functions in anti-tumor and immune-modulating activities for treating hypoglycemosis, hepatoprotection, and the effect on blood vessel system. Based on the advances in Lingzhi research in the past few decades, both G. lucidum and G. sinense are considered as the representative species of medicinal mushroom Lingzhi in China. Until 2001, G. tsugae was only advised to be used as the materials of the health products. The biologically-active components related to pharmacological functions of these three species were studied more than other Ganodermataceae family species; however, which have been used in less modern folk medicine.

Ganodermataceae: natural products and their related pharmacological functions

Ganoderic acids (GAs), a kind of highly oxygenated lanostane-type triterpenoids, are important bioactive constituents of the famous medicinal mushroom Ganoderma lucidum. They have received wide attention in recent years due to extraordinarily pharmacological functions. Submerged fermentation of G. lucidum is viewed as a promising technology for production of GAs, and substantial efforts have been devoted to process development for enhancing GA production in the last decade. This article reviews recent publication about fermentative production of GAs and their potential applications, especially the progresses toward manipulation of fermentation conditions and bioprocessing strategies are summarized. The biosynthetic pathway of GAs is also outlined.

Biotechnological production and application of ganoderic acids

Improved production of mycelial biomass and ganoderic acid by submerged culture of Ganoderma lucidum SB97 using complex media

Laccase production by the white rot fungus, Ganoderma lucidum, was investigated using submerged fermentation, and the laccase was purified and characterized. The effects of variations in the media nutrient composition or culture conditions and characteristics of purified laccase were provided for large scale production or industrial uses of the laccase. Low concentrations of glucose and yeast extract stimulated G. lucidum laccase production. The addition of lignocellulosic substrates to the media stimulated laccase production: pomelo peel induced the highest laccase activity of 11842.13 U/L and banana peel reduced laccase production, compared to control media containing wheat bran. Native PAGE and SDS PAGE demonstrated the presence of a single isoform with a molecular weight of 68 kDa. The optimum pH and temperature were 3.0 and 60°C, respectively. G. lucidum laccase is thermostable, with a residual activity of 46% after 80 min at 60°C. The Michaelis-Menten constant (Km) and catalytic constant (Kcat) values forG. lucidum laccase using ABTS (2,2'-azino-di-[3-ethyl-benzothiazolin-sulphonate]) as a substrate were 0.114 mM and 74.63 S-1, respectively, with a specificity constant (Kcat /Km) of 654.65 S-1 mM-1. The thermostable properties of the laccase produced by fermentation of G. lucidum in submerged culture had potential for industrial and biotechnology applications.

	 

	Key words: Laccase, Ganoderma lucidum, submerged fermentation, pomelo peel.

Production and characterization of thermostable laccase from the mushroom, Ganoderma lucidum, using submerged fermentation

Improvement of exopolysaccharide production by macro-fungus Auricularia auricula in submerged culture

Three strains, Bacillus subtilis B1, B. subtilis B18 and Bacillus thuringiensis B12, were screened from wheat bran to produce milk-clotting enzyme. Among them, B. subtilis B1 exhibited considerable milkclotting activity with low proteolytic activity. After response surface methodology optimization, milkclotting activity was improved from 782 SU ml -1 to 1129.05 ± 74.55 SU mL -1 with a small inoculum size (0.130%, v/v). The optimized medium contained glucose (16.2 gL -1 ), wheat bran (30 gL -1 ), NaCl (5 gL -1 ), MgSO 4 .7H 2 O (5 gL -1 ), KH 2 PO 4 (2 gL -1 ) and CaCO 3 (3 gL -1 ). The milk-clotting enzyme from B. subtilis B1 has the optimum pH 5.5 and CaCl 2 concentration 50 mmol L -1 . It is completely inactivated after 5 min at 70°C. The result showed that B. subtilis B1 was a promising strain for industrial milk-clotting enzyme production. Key words : Milk-clotting enzyme, Bacillus subtilis, submerged fermentation, wheat bran.

/pdf/production-of-milk-clotting-enzyme-by-bacillus-subtilis-b1-5fxjrr3fo0.pdf

Production of milk-clotting enzyme by Bacillus subtilis B1 from wheat bran

Pleurotus ferulae is a mushroom typically found in arid steppe that is distributed widely in the Junggar Basin of Xinjiang, China. In this work, laccase production by P. ferulae JM30X was optimized in terms of medium composition and culture conditions. After optimization, the highest laccase activity obtained was 6,832.86 U/L. A single isozyme with a molecular weight of 66 kDa was observed by SDS-PAGE and native-PAGE. Optimum pH and temperature were 3.0 and 50–70 °C, respectively. The best laccase substrate was ABTS, for which the Michaelis-Menten constant (K
 m) and catalytic efficiency (K
 cat/K
 m) value for P. ferulae laccase were 0.193 mM and 2.73 × 106 (mM s)−1, respectively. The activity of purified laccase was increased by more than four-fold by Cu2+, Mn2+ and Mg2+, while it was completely inhibited by Fe2+ and Fe3+. The production of laccase was influenced by the initial pH and K+ concentration, and the activity of purified laccase was enhanced by Cu2+, Mn2+ and Mg2+. This Pleurotus genus laccase from P. ferulae JM30X was analyzed by MS spectrum and the results are conducive to furthering our understanding of Pleurotus genus laccases.

Kechang Zhang

Papers

Improved production of mycelial biomass and ganoderic acid by submerged culture of Ganoderma lucidum SB97 using complex media

Production and characterization of thermostable laccase from the mushroom, Ganoderma lucidum, using submerged fermentation

Improvement of exopolysaccharide production by macro-fungus Auricularia auricula in submerged culture

Production of milk-clotting enzyme by Bacillus subtilis B1 from wheat bran

Production and characterization of laccase from Pleurotus ferulae in submerged fermentation