Ganoderma lucidum phosphoglucomutase is required for hyphal growth, polysaccharide production, and cell wall integrity.

Phosphoglucomutase (pgm) is an important enzyme in carbohydrate metabolism that is located at the branching point between glycolysis and the Leloir pathway. pgm catalyzes the reversible conversion reaction between glucose-6-phosphate (Glc-6-P) and glucose-1-phosphate (Glc-1-P). The glpgm gene was cloned in Escherichia coli, and the recombinant pgm protein from Ganoderma lucidum was purified in this study. The activity of native pgm was also detected to demonstrate that this predicted gene was functional in G. lucidum. Interestingly, silencing the glpgm gene in the fungus reduced hyphal growth. Moreover, glpgm silencing was associated with declining extracellular polysaccharide (EPS) production (approximately 20-40% of that in the WT strain) and increasing intracellular polysaccharide (IPS) production (approximately 1.7-fold that in the WT strain). Additionally, in our research, cell wall components were also shown to differ according to the glpgmi strain. Compared with WT, chitin significantly increased by 1.5-fold; however, the content of ß-1,3-glucan was observably reduced to 60-70% that of the WT. Further research showed that the cell wall component changes were associated with the transcription of related genes. These findings provide references for further study on the potential physiological function of pgm in G. lucidum.

Isolation and analysis of differentially expressed genes during asexual sporulation in liquid static culture of Ganoderma lucidum by suppression subtractive hybridization.

Ganoderma lucidum differentiates in liquid static culture by forming aerial mycelia and asexual spores, and this differentiation process is accompanied by higher production of anti-tumor compounds ganoderic acids. To gain an insight into the molecular events during asexual sporulation of G. lucidum, comparative transcriptome analysis using suppression subtractive hybridization (SSH) technique was performed to identify preferentially expressed genes in liquid static culture vs. in traditional shaking culture. After macroarray analysis of 1920 cDNAs from SSH library, 147 unigenes which exhibited high expression in static culture were identified. Among these sequences, putative translations of 88 unigenes possessed much similarity to known proteins involved in cell organization, signal transduction, cell metabolism, protein biosynthesis and transcription regulation; 13 had significant similarity to hypothetical proteins; the remaining 46 showed little or no similarity to GenBank sequences. RT-qPCR analysis confirmed increases in transcripts of selected genes under liquid static culture condition. The results of this study present the useful application of EST analysis on G. lucidum and provide preliminary indication of gene expression putatively involved in asexual sporulation process.

Development of a simple and efficient transformation system for the basidiomycetous medicinal fungus Ganoderma lucidum.

In this study, we report the development of a simple and efficient system for genetic transformation of the medicinal fungus Ganoderma lucidum. Various parameters were optimized to obtain successful Agrobacterium tumefaciens-mediated transformation. Co-cultivation of bacteria and protoplast at a ratio of 1,000:1 at 25°C in medium containing 0.2 mM acetosyringone was found to be the optimum condition for high efficiency transformation. Four plasmids, each carrying a different promoter driving the expression of an antibiotic resistance marker, were tested. The construct carrying the Ganoderma lucidum glyceraldehyde-3-phosphate dehydrogenase (GPD) promoter showed good transformation efficiency, whereas constructs with the GPD promoter from ascomycetes were ineffective. Our analysis showed that over 70% of the transformants tested remained mitotically stable even after five successive rounds of subculturing. We were able to detect the expression of EGFP and GUS reporter genes in the Ganoderma lucidum transformants by fluorescence imaging and histochemical staining assays respectively. Our results demonstrate a new transgenic approach that will facilitate Ganoderma lucidum research.

Functions of reactive oxygen species in apoptosis and ganoderic acid biosynthesis in Ganoderma lucidum.

Ganoderma lucidum is a medicinal fungus that is widely used in traditional medicine. Fungal PacC is recognized as an important transcription factor that functions during adaptation to environmental pH, fungal development and secondary metabolism. Previous studies have revealed that GlPacC plays important roles in mycelial growth, fruiting body development and ganoderic acid (GA) biosynthesis. In this study, using a terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) assay, we found that the apoptosis level was increased when PacC was silenced. The transcript and activity levels of caspase-like proteins were significantly increased in the PacC-silenced (PacCi) strains compared with the control strains. Silencing PacC also resulted in an increased reactive oxygen species (ROS) levels (∼2-fold) and decreased activity levels of enzymes involved in the antioxidant system. Further, we found that the intracellular ROS levels contributed to apoptosis and GA biosynthesis. Adding N-acetyl-cysteine and vitamin C decreased intracellular ROS and resulted in the inhibition of apoptosis in the PacCi strains. Additionally, the GA biosynthesis was different between the control strains and the PacCi strains after intracellular ROS was eliminated. Taken together, the findings showed that silencing PacC can result in an intracellular ROS burst, which increases cell apoptosis and GA biosynthesis levels. Our study provides novel insight into the functions of PacC in filamentous fungi.

Spore powder of Ganoderma lucidum for the treatment of Alzheimer disease: A pilot study.

BACKGROUND: This study explored the feasible efficacy and safety of the Spore Powder of Ganoderma Lucidum (SPGL) for treating patients with Alzheimer disease (AD). METHODS: Forty-two eligible patients with AD were recruited. These patients were randomly allocated to an intervention group and a control group equally. The patients in the intervention group underwent SPGL, whereas the subjects in the control received placebo. All patients were treated for a total of 6 weeks. The primary outcome was measured by Alzheimer's disease Assessment Scale-Cognitive (ADAS-cog). The secondary outcomes were measured by the World Health Organization Quality of Life questionnaire (WHOQOL-BREF) and Neuropsychiatric Index (NPI). The adverse events were also recorded during the treatment period. RESULTS: At the end of the treatment, GLSP did not show more encouraging outcomes in symptoms improvement, measured by the ADAS-cog (P = .31), and NPI (P = .79); and quality of life enhancement, measured by the WHOQOL-BREF (physical, P = .62; psychological, P = .69; social relationships, P = .75; environment, P = .82; overall quality of life, P = .74), compared with the control group. In addition, all adverse events were mild, and no significant differences were found between 2 groups. CONCLUSION: The results of this study did not find the promising efficacy of SPGL for the treatment of AD after 6-week treatment. It may be because of the relative short-term of intervention. Future clinical trials with larger sample size and longer treatment period are urgently needed.

Hypoglycemic mechanism of a novel proteoglycan, extracted from Ganoderma lucidum, in hepatocytes.

Protein tyrosine phosphatase 1 B (PTP1B) is one of main causes involved in type 2 diabetes, it dephosphorylates insulin receptor substrate (IRS) and dysregulates insulin signaling pathway, thus inducing insulin resistance. Our previous work first reported that FYGL, a neutral hyperbranched proteoglycan ingredient extracted from Ganoderma lucidum, has hypoglycemic activity in vivo and inhibitory potency on PTP1B in vitro, but the underlying mechanism was still unclear. In this study, we sought to investigate effects of FYGL on insulin signaling pathway involved with PTP1B as the targeting point in hepatocytes. We found that FYGL inhibited overexpression of PTP1B in liver tissues of ob/ob mice and HepG2 cells, significantly improved the phosphorylation of IRS1 on tyrosine residues, activated phosphatidylinositol-3 kinase (PI3K)/protein kinase B (Akt) cascades and increased phosphorylation of glycogen synthesis kinase-3ß (GSK3ß), finally enhanced insulin-stimulated glycogen synthesis in HepG2 cells and decreased blood glucose in insulin resistance model mice. Our study clearly illustrated the hypoglycemic mechanism of a novel proteoglycan possibly used in type 2 diabetes management in vivo.

Induction of apoptosis and ganoderic acid biosynthesis by cAMP signaling in Ganoderma lucidum.

Apoptosis is an essential physiological process that controls many important biological functions. However, apoptosis signaling in relation to secondary metabolite biosynthesis in plants and fungi remains a mystery. The fungus Ganoderma lucidum is a popular herbal medicine worldwide, but the biosynthetic regulation of its active ingredients (ganoderic acids, GAs) is poorly understood. We investigated the role of 3',5'-cyclic adenosine monophosphate (cAMP) signaling in fungal apoptosis and GA biosynthesis in G. lucidum. Two phosphodiesterase inhibitors (caffeine and 3-isobutyl-1-methylxanthine, IBMX) and an adenylate cyclase activator (sodium fluoride, NaF) were used to increase intracellular cAMP levels. Fungal apoptosis was identified by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assay and a condensed nuclear morphology. Our results showed that GA production and fungal apoptosis were induced when the mycelium was treated with NaF, caffeine, or cAMP/IBMX. Downregulation of squalene synthase and lanosterol synthase gene expression by cAMP was detected in the presence of these chemicals, which indicates that these two genes are not critical for GA induction. Transcriptome analysis indicated that mitochondria might play an important role in cAMP-induced apoptosis and GA biosynthesis. To the best of our knowledge, this is the first report to reveal that cAMP signaling induces apoptosis and secondary metabolite production in fungi.

Culture pH affects exopolysaccharide production in submerged mycelial culture of Ganoderma lucidum.

In submerged culture of Ganoderma lucidum, the pH optimum for cell growth has been shown to be lower than that for exopolysaccharides (EPS) formation. Therefore, in the present study, a two-stage pH-control strategy was employed to maximize the productions of mycelial biomass and EPS. When compared, a batch culture without pH control had a maximum concentration of EPS and endopolysaccharides, which was much lower than those with pH control. Maximum mycelial growth (12.5 g/L) and EPS production (4.7 g/L) were achieved by shifting the controlled pH from 3.0 to 6.0 after day 4. The contrast between the controlled-pH process and uncontrolled pH was marked. By using various two-stage culture processes, it was also observed that culture pH has a significant affect on the yield of product, mycelial morphology, chemical composition, and molecular weight of EPS. A detailed observation of mycelial morphology revealed that the productive morphological form for EPS production was a dispersed pellet (controlled pH shifting from 3.0 to 6.0) rather than a compact pellet with a dense core area (controlled pH 4.5) or a feather-like pellet (controlled pH shifting from 6.0 to 3.0). Three different polysaccharides were obtained from each pH conditions, and their molecular weights and chemical compositions were significantly different.

Links between morphology and physiology of Ganoderma lucidum in submerged culture for the production of exopolysaccharide.

Ganoderma lucidum was grown in submerged culture in shake flasks on a medium containing peptone, yeast extract and glucose. In pre-cultures, inoculated from an agar-grown culture, morphological and metabolic events were linked: the pellets originally produced protuberances when glucose was present in the medium, although glucose was not consumed. The protuberances were then liberated into the medium as second-generation pellets, at which time glucose consumption began and the rate of exopolysaccharide (EPS) production increased. The synchrony between events was repeated in cultures fed with either glucose or peptone and yeast extract. In main cultures, inoculated from a 16-day-old pre-culture, the biomass concentration increased linearly, while glucose consumption and EPS production were initially slow but then accelerated. Protuberances were produced and liberated similarly to the pre-culture, but there was less synchrony amongst the pellets. When glucose was added to such a culture on day 10, an EPS concentration of 5.7 g L(-1) was achieved on day 13, this being the highest reliable EPS concentration yet reported for submerged culture of G. lucidum. We conclude that a greater understanding of the morphological and physiological events during the culture of G. lucidum will allow the proposal of culture strategies to improve EPS production.

Two-stage culture process for improved production of ganoderic acid by liquid fermentation of higher fungus Ganoderma lucidum.

Investigations on the impact of pellet size on the cellular oxygen uptake and accumulation of ganoderic acid (GA) suggested the favorable effect of oxygen limitation on GA formation by the higher fungus Ganoderma lucidum. A two-stage fermentation process was thus proposed for enhanced GA production by combining conventional shake-flask fermentation with static culture. A high cell density of 20.9 g of DW/L (DW = dry cell weight) was achieved through a 4-day shake-flask fermentation followed by a 12-day static culture. A change in the cell morphology and a decrease in the sugar consumption rate were observed during the static culture. The GA production in the new two-stage process was considerably enhanced with its content increased from 1.36 (control) to 3.19 mg/100 mg of DW, which was much higher than previously observed.

Prevention of development of N,N'-dimethylhydrazine-induced colon tumors by a water-soluble extract from cultured medium of Ganoderma lucidum (Rei-shi) mycelia in male ICR mice.

The protective effects of a dietary water-soluble extract from cultured medium of Ganoderma lucidum (Rei-shi or Mannentake) mycelia (designated as MAK) against development of colon tumors were investigated in male ICR mice. The animals were given weekly injections of N,N'-dimethylhydrazine (DMH, 10 mg/kg body weight) for the initial 10 weeks to induce colon carcinogenesis, and then fed on diet with or without 5% MAK for 10 weeks. There were no significant differences in incidence and the total number of colon tumors between the groups. However, the MAK diet group demonstrated significantly reduced sizes of tumors in comparison with the MF diet group. Moreover, this was linked to a lowered PCNA positive index and shortening of the germinal region in the colon. beta-catenin positive tumor cell nuclei were also significantly decreased in the MAK group. The present results thus indicate that dietary MAK could act as a potent chemopreventive agent for colon carcinogenesis.

A novel approach to enhancing ganoderic acid production by Ganoderma lucidum using apoptosis induction.

Ganoderma lucidum is one of most widely used herbal medicine and functional food in Asia, and ganoderic acids (GAs) are its active ingredients. Regulation of GA biosynthesis and enhancing GA production are critical to using G. lucidum as a medicine. However, regulation of GA biosynthesis by various signaling remains poorly understood. This study investigated the role of apoptosis signaling on GA biosynthesis and presented a novel approach, namely apoptosis induction, to increasing GA production. Aspirin was able to induce cell apoptosis in G. lucidum, which was identified by terminal deoxynucleotidyl transferase mediated dUPT nick end labeling assay positive staining and a condensed nuclear morphology. The maximum induction of lanosta-7,9(11), 24-trien-3α-01-26-oic acid (ganoderic acid 24, GA24) production and total GA production by aspirin were 2.7-fold and 2.8-fold, respectively, after 1 day. Significantly lower levels of GA 24 and total GAs were obtained after regular fungal culture for 1.5 months. ROS accumulation and phosphorylation of Hog-1 kinase, a putative homolog of MAPK p38 in mammals, occurred after aspirin treatment indicating that both factors may be involved in GA biosynthetic regulation. However, aspirin also reduced expression of the squalene synthase and lanosterol synthase coding genes, suggesting that these genes are not critical for GA induction. To the best of our knowledge, this is the first report showing that GA biosynthesis is linked to fungal apoptosis and provides a new approach to enhancing secondary metabolite production in fungi.

Distinction of broken cellular wall Ganoderma lucidum spores and G. lucidum spores using FTIR microspectroscopy.

In this paper, FTIR microspectroscopy was used to identify broken cellular wall Ganoderma lucidum spores and G. lucidum spores. For IR spectra, broken cellular wall G. lucidum spores and G. lucidum spores were mainly different in the regions of 3000-2800, 1660-1600, 1400-1200 and 1100-1000 cm(-1). For curve fitting, the results showed the differences in the protein secondary structures and the polysaccharide structures/content between broken cellular wall G. lucidum spores and G. lucidum spores. Moreover, the value of A1078/A1741 might be a potentially useful factor to distinguish broken cellular wall G. lucidum spores from G. lucidum spores. Additionally, FTIR microspectroscopy could identify broken cellular wall G. lucidum spores and G. lucidum spores accurately when it was combined with hierarchical cluster analysis. The result suggests FTIR microspectroscopy is very simple and efficient for distinction of broken cellular wall G. lucidum spores and G. lucidum spores. The result also indicates FTIR microspectroscopy may be useful for TCM identification.

A new class of natural glycopeptides with sugar moiety-dependent antioxidant activities derived from Ganoderma lucidum fruiting bodies.

A water-soluble glycopeptide (PGY), fractionated and purified from the aqueous extract of the fruiting bodies of Ganoderma lucidum via two-step dialysis, anion exchange, and gel permeation chromatography, was constituted of two moieties of carbohydrate and peptide. Carbohydrate characterization with component analysis, methylation analysis, periodate oxidation, Smith degradation, enzymic hydrolysis, and IR and NMR experiments demonstrated that the carbohydrate moiety possessed a backbone of approximately 33 (1-->3)-linked beta-d-glucopyranosyl residues and side chains, at positions 6, of single alpha-l-arabinofuranosyl residues for every three Glcp residues in the main chain. On the basis of the results of amino acid composition and trypsin digestion, the peptide moiety, shown to consist of Arg, Ser, Ala, and Gly in a ratio of 1:1:2:2, exhibited the sequence of Ser-Arg-[(Ala)2(Gly)2] and was O-attached to the carbohydrate moiety via Ser. To contribute toward our understanding of the structure-activity relationship, a series of expected derivatives generated from PGY by trypsin digestion, debranching, and NaIO4 oxidation following reduction experiments, including PTC, DB-PGY, and PPP, were obtained. All of them, as well as PGY and a reference compound (butylated hydroxytoluene, BHT), were evaluated with two conventional antioxidant testing systems of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide radical scavenging and found to have their respective antioxidant activities in a concentration-dependent manner. Comparable radical-scavenging activities observed between PTC and PGY demonstrated that the removal of Ala and Gly in a peptide moiety did not result in the variation of biological functions of PGY. However, it was very interesting to note that the scavenging activity of PPP was higher for DPPH radicals, with an SC(50) value of 116.4 +/- 5.1 microg/mL, and lower for superoxide radicals, with an SC(50) value of 205.2 +/- 14.4 microg/mL, than that of PGY with corresponding SC(50) values of 133.5 +/- 5.5 and 140.5 +/- 7.7 microg/mL, and, moreover, DB-PGY displayed the weakest scavenging potency in the tested samples, indicating that the carbohydrate moiety, in particular the side chain of nonreducing end units of Araf residues as the functional region, played a vital role in the structure and antioxidant activity. In addition, compared with the SC(50) value of BHT, PGY showed lower DPPH radical-scavenging activity but possessed higher superoxide radical-quenching potency, suggesting that it could be presented as a possible new source of natural antioxidants.

[Optimization of nutrient medium for submerged cultivation of Ganoderma lucidum (Curt.: Fr.) P. Karst].

The dependence of the amount of the grown vegetative mycelium of Ganoderma lucidum on the composition of the nutrient medium has been studied under conditions of submerged cultivation. The medium was optimized using full factorial and steepest ascent experimental designs. The addition of two carbon sources to the medium considerably improved the submerged growth of the fungus. An optimized medium provided for a high yield (20-20.95 g/l) of the morphologically homogeneous mycelium and shortened the cultivation period to 3-4 days.