Biotechnological production and application of ganoderic acids

Mushroom-Mediated Redox Reactions

The application of biocatalysts in organic synthesis has grown significantly in recent years, and both academia and industry are continuously searching for novel biocatalysts capable of performing challenging chemical reactions. Mushrooms are a rich source of ligninolytic and secondary metabolite biosynthetic enzymes, and therefore were considered promising biocatalysts for organic synthesis. This review focuses on the broad utilization potential of mushroom-based biocatalysts and highlights key advances in mushroom-mediated redox reactions. It mainly includes the reduction of ketones and carboxylic acids, hydroxylation of aromatic and aliphatic compounds, epoxidation of olefins, oxidative cleavage of alkenes, and other uncommon reactions catalyzed by the whole cells or purified enzymes of mushroom origin. Overall, a comprehensive overview of the applications of mushrooms as biocatalysts in organic synthesis is provided, which puts this versatile microorganism in the spotlight of further research.

Optimization of Submerged Fermentation Conditions for Polysaccharide Production in Species of the Genus Ganoderma (Agaricomycetes) and Comparative Analysis of the Antioxidant Activities of Different Strains

Species of the genus Ganoderma are important medicinal and edible mushrooms, with polysaccharides being its main active ingredient. The submerged fermentation of Ganoderma is an important source of polysaccharides in the mycelia. In this study, a single factor test and an orthogonal test were employed to optimize the medium and fermentation conditions with the objective of obtaining a high content of polysaccharide in the liquid submerged fermentation culture mycelia of Ganoderma species. The results demonstrated that the optimal culture medium formula for polysaccharide accumulation in mycelia was: soluble starch, 25 g/L; wheat bran, 3 g/L; and KH2PO4, 4.5 g/L, with a pH of 4.0, and the optimal culture conditions were a temperature of 27°C, a rotational speed of 90 r/min, and an incubation period of 11 d. Furthermore, the mycelia of 20 strains from nine species of Ganoderma were cultured under optimal fermentation conditions, and the content of polysaccharide in mycelia and its antioxidant activity were analyzed. The findings revealed that the polysaccharide content in the mycelia of strains GD and Du996 was notably elevated, at 56.97 and 53.22 mg/g, respectively. The polysaccharide content was found to be high in the mycelia of G. sichuanense and G. lucidum, with an average of 35 mg/g. Nevertheless, no notable discrepancy was observed in the polysaccharide content of the mycelia of the cultivated and wild strains. Moreover, the antioxidant activity analysis revealed that the DPPH clearance rate of strains Du1320, Du280, and GD was 92.85%, 90.86%, and 89.06%, respectively. The ABTS clearance rate of strain GSD was the highest (75.39%), and the hydroxyl radical clearance rate of strain GD was the highest (81.98%). In conclusion, this study optimized the medium and conditions for high polysaccharide yield in the liquid submerged fermentation culture of Ganoderma and identified the strains with the highest yield and antioxidant activity. The present results may provide a theoretical basis for the future production of polysaccharides in mycelia by liquid fermentation of Ganoderma as well as for the development and utilization of strains with high polysaccharide yield and antioxidant activity.

Exploring Ganoderma lucidum: morphology, cultivation and market potential

Ganoderma lucidum, known as the "mushroom of immortality," is a white rot fungus renowned for its medicinal properties, attributed to its bioactive compounds. Although species with similar morphological traits to G. lucidum are found across the globe, precise identification is made possible through DNA barcoding and molecular phylogenetic analysis. Global cultivation and wild harvesting of G. lucidum are both done in response to the growing market needs. Artificial cultivation is typically performed on sawdust, but other woody substrates and the wood log method are also employed. This cultivation leverages the fungus's ecological role in converting industrial and agricultural solid wastes into biomass, thereby producing functional food and potential pharmaceutical sources. The review consolidates research on various aspects of, including cultivation methods (sawdust, agricultural waste, wood logs, and submerged fermentation), and the current global market conditions.

Breeding a new Ganoderma lucidum strain with increased contents of individual ganoderic acids by mono-mono crossing of genetically modified monokaryons

Ganoderic acids (GAs) are major functional components of Ganoderma lucidum. The study aimed to breed a new G. lucidum strain with increased contents of individual GAs. Two mating-compatible monokaryotic strains, G. 260125 and G. 260124, were successfully isolated from the dikaryotic G. lucidum CGMCC 5.0026 via protoplast formation and regeneration. The Vitreoscilla hemoglobin gene (vgb) and squalene synthase gene (sqs) were overexpressed in the monokaryotic G. 260124 and G. 260125 strain, respectively. Mating between the G. 260124 strain overexpressing vgb and the G. 260125 strain overexpressing sqs resulted in the formation of the new hybrid dikaryotic G. lucidum strain sqs-vgb. The maximum contents of ganoderic acid (GA)-T, GA-Me, and GA-P in the fruiting body of the mated sqs-vgb strain were 23.1, 15.3, and 39.8 μg/g dry weight (DW), respectively, 2.23-, 1.75-, and 2.69-fold greater than those in G. lucidum 5.0026. The squalene and lanosterol contents increased 2.35- and 1.75-fold, respectively, in the fruiting body of the mated sqs-vgb strain compared with those in the G. lucidum 5.0026. In addition, the maximum expression levels of the sqs and lanosterol synthase gene (ls) were increased 3.23- and 2.13-fold, respectively, in the mated sqs-vgb strain. In summary, we developed a new G. lucidum strain with higher contents of individual GAs in the fruiting body by integrating genetic engineering and mono-mono crossing.

Chemodiversity, pharmacological activity, and biosynthesis of specialized metabolites from medicinal model fungi Ganoderma lucidum

Ganoderma lucidum is a precious fungus, particularly valued for its dual use as both medicine and food. Ganoderic acids (GAs), the distinctive triterpenoids found in the Ganoderma genus, exhibit a wide range of pharmacological activities. However, the limited resources of GAs restrict their clinic usage and drug discovery. In this review, we presented a comprehensive summary focusing on the diverse structures and pharmacological activity of GAs in G. lucidum. Additionally, we discussed the latest advancements in the elucidation of GA biosynthesis, as well as the progress in heterosynthesis and liquid fermentation methods aimed at further increasing GA production. Furthermore, we summarized the omics data, genetic transformation system, and cultivation techniques of G. lucidum, described as medicinal model fungi. The understanding of Ganoderic acids chemodiversity and biosynthesis in medicinal model fungi Ganoderma lucidum will provide important insights into the exploration and utilization of natural products in medicinal fungi.

Influence of cultivation substrate on antioxidant activities and triterpenoid profiles of the fruiting body of Ganoderma lucidum

Introduction

The fruiting body of Ganoderma lucidum has been believed to possess a wide range of therapeutic effects. There are two main methods for artificial cultivation of G. lucidum to produce the fruiting body, namely wood log cultivation and substitute cultivation. The impact of cultivation substrates on the composition of bioactive compounds remains largely unexplored. This study aims to compare the antioxidant activities and triterpenoid profiles of the fruiting bodies of G. lucidum that cultivated through wood log cultivation (WGL) and substitute cultivation (SGL) methods.

Methods

The antioxidant activities, including the DPPH radical scavenging, hydroxyl radical scavenging, superoxide radical scavenging, and total antioxidant activities, were assessed in both WGL and SGL samples. Furthermore, the UHPLC-Q-Orbitrap-MS technique was employed to compare their phytochemical profiles, with a specific emphasis on triterpenoid constituents.

Results and discussion

It was found that WGL samples exhibited significantly higher total triterpenoid content, DPPH radical scavenging activity, and total antioxidant activity. Furthermore, an untargeted metabolomics approach employing UHPLC-Q-Orbitrap-MS tentatively identified a total of 96 triterpenoids. Distinguishingly different triterpenoid profiles between the two types of G. lucidum samples were revealed via the utilization of principal component analysis (PCA) and hierarchical cluster analysis (HCA). Specifically, 17 triterpenoids showed significant differences. Of these triterpenoids, 6 compounds, such as ganosporelactone B, ganoderol A, ganoderic acid A, ganoderic acid alpha, were significantly higher in SGL samples; 11 compounds, such as lucidenic acid A, lucidenic acid D1, lucidenic acid F, lucidenic acid G, lucidenic acid J, ganoderic acid E, and ganoderic acid O, were significantly higher in WGL samples. These findings expand our knowledge regarding the impact of cultivation substrate on the antioxidant activities and triterpenoid profiles of G. lucidum, and offer practical implications for its cultivation.

The putatively high-altitude adaptation of macaque monkeys: Evidence from the fecal metabolome and gut microbiome

Animals living in high-altitude environments, such as the Tibetan Plateau, must face harsh environmental conditions (e.g., hypoxia, cold, and strong UV radiation). These animals' physiological adaptations (e.g., increased red cell production and turnover rate) might also be associated with the gut microbial response. Bilirubin is a component of red blood cell turnover or destruction and is excreted into the intestine and reduced to urobilinoids and/or urobilinogen by gut bacteria. Here, we found that the feces of macaques living in high-altitude regions look significantly browner (with a high concentration of stercobilin, a component from urobilinoids) than those living in low-altitude regions. We also found that gut microbes involved in urobilinogen reduction (e.g., beta-glucuronidase) were enriched in the high-altitude mammal population compared to the low-altitude population. Moreover, the spatial-temporal change in gut microbial function was more profound in the low-altitude macaques than in the high-altitude population, which might be attributed to profound changes in food resources in the low-altitude regions. Therefore, we conclude that a high-altitude environment's stress influences living animals and their symbiotic microbiota.

Biotransformation of triterpenoid ganoderic acids from exogenous diterpene dihydrotanshinone I in the cultures of Ganoderma sessile

BACKGROUND

Triterpenoids have shown a wide range of biological activities including antitumor and antiviral effects. Typically, triterpenes are synthesized through the mevalonate pathway and are extracted from natural plants and fungi. In this work, triterpenoids, ganoderic acids (GAs) were discovered to be produced via biotransformation of a diterpene, 15,16-dihydrotanshinone I (DHT) in the liquid cultured Ganoderma sessile mycelium.

RESULTS

Firstly, the biotransformation products, two rare GAs were isolated and purified by column chromatography, and characterized using HR-ESI-MS spectrometry and NMR spectrometry. The two compounds were Lanosta-7,9(11),24-trien-15α,22,β-diacetoxy-3β-hydroxy-26-oic acid (LTHA) and Lanosta-7,9(11),24-trien-15α,22,β-diacetoxy-3β-carbonyl-26-oic acid (LTCA). Then, transcriptome and proteome technologies were employed to measure the expression of mRNA and protein, which further confirmed that triterpenoid GAs could be transformed from exogenous diterpenoid DHT. At the molecular level, we proposed a hypothesis of the mechanism by which DHT converted to GAs in G. sessile mycelium, and the possible genes involved in biotransformation were verified by RT-qPCR.

CONCLUSIONS

Two rare GAs were obtained and characterized. A biosynthetic pathway of GAs from DHT was proposed. Although the synthetic route was not confirmed, this study provided important insights into omics resources and candidate genes for studying the biotransformation of diterpenes into triterpenes.

Novel Ganoderma triterpenoid saponins from the biotransformation-guided purification of a commercial Ganoderma extract

Ganoderma sp. contains high amounts of diverse triterpenoids; however, few triterpenoid saponins could be isolated from the medicinal fungus. To produce novel Ganoderma triterpenoid saponins, biotransformation-guided purification (BGP) process was applied to a commercial Ganoderma extract. The commercial Ganoderma extract was partially separated into three fractions by preparative high-performance liquid chromatography, and the separated fractions were then directly biotransformed by a Bacillus glycosyltransferase (BsUGT489). One of the biotransformed products could be further purified and identified as a novel saponin: ganoderic acid C2 (GAC2)-3-O-β-glucoside by nucleic magnetic resonance (NMR) and mass spectral analyses. Based on the structure of the saponin, the predicted precursor should be the GAC2, which was confirmed to be biotransformed into four saponins, GAC2-3-O-β-glucoside, GAC2-3,15-O-β-diglucoside and two unknown GAC2 monoglucosides, revealed by NMR and mass spectral analyses. GAC2-3-O-β-glucoside and GAC2-3,15-O-β-diglucoside possessed 17-fold and 200-fold higher aqueous solubility than that of GAC2, respectively. In addition, GAC2-3-O-β-glucoside retained the most anti-α-glucosidase activity of GAC2 and was comparable with that of the anti-diabetes drug (acarbose). The present study showed that the BGP process is an efficient strategy to survey novel and bioactive molecules from crude extracts of natural products.

Effects of glutamate oxaloacetate transaminase on reactive oxygen species in Ganoderma lucidum

Nitrogen metabolism can regulate mycelial growth and secondary metabolism in Ganoderma lucidum. As an important enzyme in intracellular amino acid metabolism, glutamate oxaloacetate transaminase (GOT) has many physiological functions in animals and plants, but its function in fungi has been less studied. In the present study, two GOT isoenzymes were found in G. lucidum; one is located in the mitochondria (GOT1), and the other is located in the cytoplasm (GOT2). The reactive oxygen species (ROS) level was increased in got1 silenced strains and was approximately 1.5-fold higher than that in the wild-type (WT) strain, while silencing got2 did not affect the ROS level. To explore how GOT affects ROS in G. lucidum, experiments related to the generation and elimination of intracellular ROS were conducted. First, compared with that in the WT strain, the glutamate content, one of the substrates of GOT, decreased when got1 or got2 was knocked down, and the glutathione (l-γ-glutamyl-l-cysteinylglycine) (GSH) content decreased by approximately 38.6%, 19.3%, and 40.1% in got1 silenced strains, got2 silenced strains, and got1/2 co-silenced strains respectively. Second, GOT also affects glucose metabolism. The pyruvate (PA), acetyl-CoA and α-ketoglutarate (α-KG) contents decreased in got1 and got2 silenced strains, and the transcription levels of most genes involved in the glycolytic pathway and the tricarboxylic acid cycle increased. The NADH content was increased in got1 silenced strains and got2 silenced strains, and the NAD⁺/NADH ratio was decreased, which might result in mitochondrial ROS production. Compared with the WT strain, the mitochondrial ROS level was approximately 1.5-fold higher in the got1 silenced strains. In addition, silencing of got1 or got2 resulted in a decrease in antioxidant enzymes, including superoxide dismutase, catalase, glutathione reductase, and ascorbate peroxidase. Finally, ganoderic acid (GA) was increased by approximately 40% in got1 silenced strains compared with the WT strain, while silencing of got2 resulted in a 10% increase in GA biosynthesis. These findings provide new insights into the effect of GOT on ROS and secondary metabolism in fungi. KEY POINTS: • GOT plays important roles in ROS level in Ganoderma lucidum. • Silencing of got1 resulted in decrease in GSH content and antioxidant enzymes activities, but an increase in mitochondrial ROS level in G. lucidum. • Silencing of got1 and got2 resulted in an increase in ganoderic acid biosynthesis in G. lucidum.

The role of post-transcriptional modification on a new tRNAIle(GAU) identified from Ganoderma lucidum in its fragments' cytotoxicity on cancer cells

Ganoderma lucidum (Ganoderma) is a famous Chinese herbal medicine which has been used clinically for thousands of years in China. Despite numerous studies on triterpenes and polysaccharides, the bioactivity of RNAs abundant in Ganoderma remains unknown. Here, based on LC-MS techniques, dihydrouracil, 5-methyluridine (m⁵U) and pseudouridine were identified at position 19, 52 and 53 of a new tRNA^Ile(GAU) which was isolated as the most abundant tRNA species in Ganoderma, and is the first purified tRNA from fungus. Cytotoxic screening of tRNA-half (t-half) and tRNA fragment (tRF) derived from this tRNA, as well as their mimics (t-half or tRF as antisense strand), demonstrated that the double-stranded form, i.e., tRF and t-halve mimics, exhibited stronger cytotoxicity than their single-stranded form, and the cytotoxicity of t-half mimic is significantly stronger than that of tRF mimic. Notably, the cytotoxicity of 3'-t-half mimic is not only much more potent than that of taxol, but also is much more potent than that of ganoderic acids, the major bioactive components in Ganoderma. Furthermore, 3'-t-half mimic_M2 (m⁵U modified) exhibited significantly stronger cytotoxicity than unmodified 3'-t-half mimic, which is consistent with the computational simulation showing that m⁵U modification enhances the stability of the tertiary structure of 3'-t-half mimic. Overall, the present study not only indicates t-halves are bioactive components in Ganoderma which should not be neglected, but also reveals an important role of post-transcriptional modification on tRNA in its fragments' cytotoxicity against cancer cells, which benefits the design and development of RNAi drugs from natural resource.

Increasing the production of the bioactive compounds in medicinal mushrooms: an omics perspective

Macroscopic fungi, mainly higher basidiomycetes and some ascomycetes, are considered medicinal mushrooms and have long been used in different areas due to their pharmaceutically/nutritionally valuable bioactive compounds. However, the low production of these bioactive metabolites considerably limits the utilization of medicinal mushrooms both in commerce and clinical trials. As a result, many attempts, ranging from conventional methods to novel approaches, have been made to improve their production. The novel strategies include conducting omics investigations, constructing genome-scale metabolic models, and metabolic engineering. So far, genomics and the combined use of different omics studies are the most utilized omics analyses in medicinal mushroom research (both with 31% contribution), while metabolomics (with 4% contribution) is the least. This article is the first attempt for reviewing omics investigations in medicinal mushrooms with the ultimate aim of bioactive compound overproduction. In this regard, the role of these studies and systems biology in elucidating biosynthetic pathways of bioactive compounds and their contribution to metabolic engineering will be highlighted. Also, limitations of omics investigations and strategies for overcoming them will be provided in order to facilitate the overproduction of valuable bioactive metabolites in these valuable organisms.

Effect of Methyl Jasmonate Elicitation on Triterpene Production and Evaluation of Cytotoxic Activity of Mycelial Culture Extracts of Ganoderma applanatum (Pers.) Pat

Abiotic elicitation, a well-known strategy in mushroom biotechnology, promotes increased accumulation of secondary metabolites in mycelial cultures. The study aimed the effects of methyl jasmonate (MeJA) on the production of triterpenes in submerged cultures of Ganoderma applanatum. Further, the study evaluated the cytotoxic activity of the extract corresponding to the optimal elicitation variant in selected human cancer cell lines as well as the selectivity against normal cells. MeJA was added on days 1, 4, 6, and 8 in the 10-day growth cycle at concentrations of 10, 50, 100, 150, and 200 µM MeJA. The HPLC-DAD was used to analyze the triterpenes. The cytotoxic activity was tested using the MTTFc assay in grouped panels of skin, prostate, and gastrointestinal cancer cells. The results of the quantitative analyses confirmed the stimulating effect of MeJA on the production of ganoderic acid A and ganoderic acid C. The greatest increase in total triterpenes was found on day 6 of the culture cycle compared to the control group-with the concentration of MeJA-150 µM. Compared to the control samples, mycelial culture extract after the most productive elicitation variant showed significant cytotoxic activity against prostate cancer cells and moderate effects on melanoma cells. Ganoderma applanatum mycelial cultures can be proposed as a model to study the dynamics of the accumulation of compounds with therapeutic values through abiotic elicitation.

Characterization and Biological Studies of the Terpenoids from Ganoderma resinaceum and Serpula similis (Agaricomycetes)

Mycochemical properties and bioactivities of Ganoderma resinaceum and Serpula similis remain unexplored. The present study assessed antioxidant, cytotoxicity, and cell migration abilities of Ganoderma and Serpula extracts, followed by their phytochemical analyses. The MTT assay was conducted to determine the cytotoxicity along with the cell migration studies in human cancer cell lines. The antioxidant profiles were evaluated through DPPH and FRAP assays. Furthermore, LC-MS/MS analysis was performed to elucidate the phytochemicals responsible for anticancer and antioxidant activities. Significant concentration-dependent cytotoxicities of 12.7% and 13.7% were observed against HCT 116 cell lines at 1% and 5% concentrations of the G. resinaceum extract, respectively. Similarly, significant concentration-dependent cytotoxicities of 6.7% and 25.5% were observed at 1% and 5% concentrations of the S. similis extract, respectively. The extracts of G. resinaceum and S. similis both shows better anti-migration potential in lung cancer cells. Both extracts demonstrated good scavenging activity on DPPH and ferric ion free radicals. LC-MS analysis revealed 11 compounds from S. similis and 15 compounds from G. resinaceum fruiting bodies. Compounds such as terpenoids, alkaloids, cytotoxic peptides, and other metabolites were identified as major components in both extracts. These extracts exhibited cytotoxic activity against HCT 116 cancer cells, along with moderate antioxidant activity. This implies that the extracts might be used as bioactive natural sources in the pharmaceutical and food industries.

Biosynthesis of mushroom-derived type II ganoderic acids by engineered yeast

Type II ganoderic acids (GAs) produced by the traditional medicinal mushroom Ganoderma are a group of triterpenoids with superior biological activities. However, challenges in the genetic manipulation of the native producer, low level of accumulation in the farmed mushroom, the vulnerabilities of the farming-based supply chain, and the elusive biosynthetic pathway have hindered the efficient production of type II GAs. Here, we assemble the genome of type II GAs accumulating G. lucidum accession, screen cytochrome P450 enzymes (CYPs) identified from G. lucidum in baker's yeast, identify key missing CYPs involved in type II GAs biosynthesis, and investigate the catalytic reaction sequence of a promiscuous CYP. Then, we engineer baker's yeast for bioproduciton of GA-Y (3) and GA-Jb (4) and achieve their production at higher level than those from the farmed mushroom. Our findings facilitate the further deconvolution of the complex GA biosynthetic network and the development of microbial cell factories for producing GAs at commercial scale.

The Effect of Mitochondria on Ganoderma lucidum Growth and Bioactive Components Based on Transcriptomics

Mitochondria are the power source of living cells and implicated in the oxidative metabolism. However, the effect of mitochondria on breeding is usually ignored in conventional research. In this study, the effect of mitochondria on Ganoderma lucidum morphology, yield, and main primary bioactive components was analyzed via structuring and comparing isonuclear alloplasmic strains. The crucial biological pathways were then explored based on the transcriptome. The results showed that isonuclear alloplasmic exhibited difference in mycelial growth rate in potato dextrose agar medium (PDA), basidiospore yield, and polysaccharide and triterpenoid content. Otherwise, mitochondria did not change colony and fruit body morphology, mushroom yield, or mycelial growth rate in solid-state fermentation cultivation material. The transcriptome data of two significant isonuclear alloplasmic strains S1 and S5 revealed that the involvement of differentially expressed genes (DEGs) was mainly in pentose and glucuronate interconversions, starch and sucrose metabolism, and steroid biosynthesis. The result was further confirmed by the other isonuclear alloplasmic strains. The above results further proved that mitochondria could affect the active components of G. lucidum. Our results provide information which will contribute to understanding of mitochondria and will be helpful for breeding improved varieties.

A methyltransferase LaeA regulates ganoderic acid biosynthesis in Ganoderma lingzhi

The methyltransferase LaeA is a global regulator involved in the biosynthesis of secondary metabolites by ascomycete fungi. However, little is known of its regulatory role in basidiomycete fungi. In this study, the laeA gene was identified in the basidiomycete Ganoderma lingzhi and its function in regulating the biosynthesis of anti-tumor ganoderic acids was evaluated. A laeA deletion (ΔlaeA) Ganoderma strain exhibited significantly reduced concentration of ganoderic acids. qRT-PCR analysis further revealed that the transcription levels of genes involved in the biosynthesis of ganoderic acids were drastically lower in the ΔlaeA strain. Moreover, deletion of laeA resulted in decreased accumulation of intermediates and abundances of asexual spores in liquid static culture of G. lingzhi. In contrast, constitutive overexpression of laeA resulted in increased concentration of ganoderic acids. These results demonstrate an essential role of LaeA in the regulation of ganoderic acid biosynthesis in Ganoderma.

Nutraceutical Enrichment of Animal Feed by Filamentous Fungi Fermentation

There is an urgent need for improvements in animal production, particularly for ruminants, such that more sustainable and efficient processes are developed for obtaining more nutritious and efficient feeds. Filamentous fungi can add value to residual plant biomass, and may also have the potential to produce metabolites and enrich plant biomasses used in animal nutrition, converting them into nutraceutical sources. Thus, in this work, filamentous fungal fermentation of ruminant feed biomasses commonly used in Brazil was performed, and the enrichment for bioactive metabolites was tested. For this, Fistulina hepatica, Ganoderma lucidum, Pleurotus pulmonarius, Panus lecomtei, and Aspergillus terreus were grown for 28 days on different substrates: starchy grains- (sorghum, oat, and corn), fibrous substrates (coast-cross, rice husk, and moringa plant) and protein-rich substrates (cottonseed cake and pigeon pea plant). Fermented substrates were evaluated for laccase activity, crude protein, β-glucan, and lovastatin content. The highest growth rate was observed for G. lucidum in oat substrate (OT-01) (0.708 ± 0.035 cm/day) and F. hepatica in oat + coast-cross + pigeon pea treatment (OT-10) (0.607 ± 0.012 cm/day). High laccase activity was observed for P. lecomtei grown in starchy grain + moringa + pigeon pea substrate, reaching an activity of 416.8 ± 20.28 U/g. A. terreus growth in ST-09 (sorghum + pigeon pea) showed higher protein (15.3 ± 0.46%), β-glucan (503.56 ± 8.6 mg/g) and lovastatin (1.10 ± 0.17 mg/g) content compared to untreated substrates. These results demonstrate that filamentous fungi are an alternative for nutraceutical enrichment of ruminant feed biomasses. To the best of our knowledge, this is the first report in which P. lecomtei and F. hepatica are evaluated for their ability to be cultivated in ruminant feed substrates from Brazil.

Ganoderic acid A ameliorates non‑alcoholic streatohepatitis (NASH) induced by high‑fat high‑cholesterol diet in mice

Non-alcoholic steatohepatitis (NASH) is becoming a huge global health problem. Previous studies have revealed that ganoderic acids have hepatoprotective and hypocholesterolemic effects. In the present study, to evaluate the anti-NASH activity of ganoderic acid A (GAA), male 6-week-old C57BL/6J mice were divided into the following four groups, which were administered different diets: Normal diet (ND group), high-fat high-cholesterol diet (HFHC group), HFHC diet supplemented with 25 mg/kg/day (GAAL group) or 50 mg/kg/day of GAA (GAAH group). After 12 weeks of GAA treatment, histopathological results revealed that compared with that of the HFHC group, GAA significantly inhibited fat accumulation, steatosis, inflammation and fibrosis in the liver. GAA effectively reduced serum aspartate transaminase and alanine transaminase levels compared with the HFHC model. Furthermore, the endoplasmic reticulum (ER) stress-responsive proteins, including glucose-regulated protein 78, phosphorylated (p)-eukaryotic initiation factor-2α and p-JNK, were significantly suppressed by GAA, while ERp57, p-MAPK and p-AKT were significantly increased after GAA treatment. Taken together, it was concluded that GAA could resist HFHC diet-induced NASH. In terms of its underlying mechanism, GAA could improve liver inflammation and fibrosis by inhibiting hepatic oxidative stress and the ER stress response induced by HFHC.

Valorisation of biomass and diaper waste into a sustainable production of the medical mushroom Lingzhi Ganoderma lucidum

Global solid waste is expected to increase by at least 70% annually until year 2050. The mixture of solid waste including food waste from food industry and domestic diaper waste in landfills is causing environmental and human health issues. Nevertheless, food and diaper waste containing high lignocellulose can easily degrade using lignocellulolytic enzymes thereby converted into energy for the development and growth of mushroom. Therefore, this study explores the potential of recycling biomass waste from coffee ground, banana, eggshell, tea waste, sugarcane bagasse and sawdust and diaper waste as raw material for Lingzhi mushroom (Ganoderma lucidum) cultivation. Using 2% of diaper core with sawdust biowaste leading to the fastest 100% mushroom mycelium spreading completed in one month. The highest production yield is 71.45 g mushroom; this represents about 36% production biological efficiency compared to only 21% as in commercial substrate. The high mushroom substrate reduction of 73% reflect the valorisation of landfill waste. The metabolomics profiling showed that the Lingzhi mushroom produced is of high quality with a high content of triterpene being the bioactive compounds that are medically important for treating assorted disease and used as health supplement. In conclusion, our study proposed a potential resource management towards zero-waste and circular bioeconomy for high profitable mushroom cultivation.

Edible Mushrooms: A Comprehensive Review on Bioactive Compounds with Health Benefits and Processing Aspects

Mushrooms are well-known functional foods due to the presence of a huge quantity of nutraceutical components. These are well recognized for their nutritional importance such as high protein, low fat, and low energy contents. These are rich in minerals such as iron, phosphorus, as well as in vitamins like riboflavin, thiamine, ergosterol, niacin, and ascorbic acid. They also contain bioactive constituents like secondary metabolites (terpenoids, acids, alkaloids, sesquiterpenes, polyphenolic compounds, lactones, sterols, nucleotide analogues, vitamins, and metal chelating agents) and polysaccharides chiefly β-glucans and glycoproteins. Due to the occurrence of biologically active substances, mushrooms can serve as hepatoprotective, immune-potentiating, anti-cancer, anti-viral, and hypocholesterolemic agents. They have great potential to prevent cardiovascular diseases due to their low fat and high fiber contents, as well as being foremost sources of natural antioxidants useful in reducing oxidative damages. However, mushrooms remained underutilized, despite their wide nutritional and bioactive potential. Novel green techniques are being explored for the extraction of bioactive components from edible mushrooms. The current review is intended to deliberate the nutraceutical potential of mushrooms, therapeutic properties, bioactive compounds, health benefits, and processing aspects of edible mushrooms for maintenance, and promotion of a healthy lifestyle.

Potential hepatoprotective effects of flavonoids contained in propolis from South Sulawesi against chemotherapy agents

The use of doxorubicin and epirubicin as chemotherapy agent causes side effects such as liver damage due to oxidative stress by reactive oxygen species (ROS) that cause increased of ALT and AST level as liver parameter. One source of natural antioxidants as ROS neutralizer comes from flavonoid that contain in propolis. Most researchers claim that flavonoid can be used to protect the liver. The aim of this study was to test the hepatoprotective effect of flavonoid in propolis from South Sulawesi against doxorubicin and epirubicin. The experiment included male Sprague dawley rats divided into nine groups. The rats received the microcapsule propolis or the quercetin orally for 15 days. The hepatotoxicity was promoted by injection epirubicin and doxorubicin (i.v.) with a cumulative dose of 9 mg/kg. In this study, total polyphenol and flavonoid tests of propolis have been carried out, there were 1.1% polyphenols and 2.7% flavonoids, the antioxidant activity tests showed IC50 value of 9849 ppm and LCMS/MS tests supported the presence of phenolic compounds in propolis from South Sulawesi. Liver parameter was measured and the results showed that the propolis 200 mg/kg group produced the lowest ALT and had potential protective effect against doxorubicin and epirubicin-induced hepatotoxicity.

Glycosylation of Ganoderic Acid G by Bacillus Glycosyltransferases

Ganoderma lucidum is a medicinal fungus abundant in triterpenoids, its primary bioactive components. Although numerous Ganoderma triterpenoids have already been identified, rare Ganoderma triterpenoid saponins were recently discovered. To create novel Ganoderma saponins, ganoderic acid G (GAG) was selected for biotransformation using four Bacillus glycosyltransferases (GTs) including BtGT_16345 from the Bacillus thuringiensis GA A07 strain and three GTs (BsGT110, BsUGT398, and BsUGT489) from the Bacillus subtilis ATCC 6633 strain. The results showed that BsUGT489 catalyzed the glycosylation of GAG to GAG-3-o-β-glucoside, while BsGT110 catalyzed the glycosylation of GAG to GAG-26-o-β-glucoside, which showed 54-fold and 97-fold greater aqueous solubility than that of GAG, respectively. To our knowledge, these two GAG saponins are new compounds. The glycosylation specificity of the four Bacillus GTs highlights the possibility of novel Ganoderma triterpenoid saponin production in the future.

Ganoderma lucidum: A potential source to surmount viral infections through β-glucans immunomodulatory and triterpenoids antiviral properties

Ganoderma lucidum (G. lucidum) polysaccharides and triterpenoids are the major bioactive compounds and have been used as traditional medicine for ancient times. Massive demands of G. lucidum have fascinated the researchers towards its application as functional food, nutraceutical and modern medicine owing to wide range of application in various diseases include immunomodulators, anticancer, antiviral, antioxidant, cardioprotective, hepatoprotective. G. lucidum polysaccharides exhibit immunomodulatory properties through boosting the action of antigen-presenting cells, mononuclear phagocyte system, along with humoral and cellular immunity. β-Glucans isolated from G. lucidum are anticipated to produce an immune response through pathogen associated molecular patterns (PAMPs). β-Glucans after binding with dectin-1 receptor present on different cells include macrophages, monocytes, dendritic cells and neutrophils produce signal transduction that lead to trigger the mitogen-activated protein kinases (MAPKs), T cells and Nuclear factor-κB (NF-κB) that refer to cytokines production and contributing to immune response. While triterpenoids produce antiviral effects through inhibiting various enzymes like neuraminidase, HIV-protease, DENV2 NS2B-NS3 protease and HSV multiplication. Polysaccharides and triterpenoids adjunct to other drugs exhibit potential action in prevention and treatment of various diseases. Immunomodulators and antiviral properties of this mushroom could be a potential source to overcome this current pandemic outbreak.

One-Pot Bi-Enzymatic Cascade Synthesis of Novel Ganoderma Triterpenoid Saponins

Ganoderma lucidum is a medicinal fungus whose numerous triterpenoids are its main bioactive constituents. Although hundreds of Ganoderma triterpenoids have been identified, Ganoderma triterpenoid glycosides, also named triterpenoid saponins, have been rarely found. Ganoderic acid A (GAA), a major Ganoderma triterpenoid, was synthetically cascaded to form GAA-15-O-β-glucopyranoside (GAA-15-G) by glycosyltransferase (BtGT_16345) from Bacillus thuringiensis GA A07 and subsequently biotransformed into a series of GAA glucosides by cyclodextrin glucanotransferase (Toruzyme® 3.0 L) from Thermoanaerobacter sp. The optimal reaction conditions for the second-step biotransformation of GAA-15-G were found to be 20% of maltose; pH 5; 60 °C. A series of GAA glucosides (GAA-G2, GAA-G3, and GAA-G4) could be purified with preparative high-performance liquid chromatography (HPLC) and identified by mass and nucleic magnetic resonance (NMR) spectral analysis. The major product, GAA-15-O-[α-glucopyranosyl-(1→4)-β-glucopyranoside] (GAA-G2), showed over 4554-fold higher aqueous solubility than GAA. The present study demonstrated that multiple Ganoderma triterpenoid saponins could be produced by sequential actions of BtGT_16345 and Toruzyme®, and the synthetic strategy that we proposed might be applied to many other Ganoderma triterpenoids to produce numerous novel Ganoderma triterpenoid saponins in the future.

Fungal natural products galaxy: Biochemistry and molecular genetics toward blockbuster drugs discovery

Secondary metabolites synthesized by fungi have become a precious source of inspiration for the design of novel drugs. Indeed, fungi are prolific producers of fascinating, diverse, structurally complex, and low-molecular-mass natural products with high therapeutic leads, such as novel antimicrobial compounds, anticancer compounds, immunosuppressive agents, among others. Given that these microorganisms possess the extraordinary capacity to secrete diverse chemical scaffolds, they have been highly exploited by the giant pharma companies to generate small molecules. This has been made possible because the isolation of metabolites from fungal natural sources is feasible and surpasses the organic synthesis of compounds, which otherwise remains a significant bottleneck in the drug discovery process. Here in this comprehensive review, we have discussed recent studies on different fungi (pathogenic, non-pathogenic, commensal, and endophytic/symbiotic) from different habitats (terrestrial and marines), the specialized metabolites they biosynthesize, and the drugs derived from these specialized metabolites. Moreover, we have unveiled the logic behind the biosynthesis of vital chemical scaffolds, such as NRPS, PKS, PKS-NRPS hybrid, RiPPS, terpenoids, indole alkaloids, and their genetic mechanisms. Besides, we have provided a glimpse of the concept behind mycotoxins, virulence factor, and host immune response based on fungal infections.

Culinary and Medicinal Mushrooms: Insight into Growing Technologies

Humans have used mushrooms from the beginning of their history. However, during the last few decades, the market demand for these fruiting bodies has increased significantly owing to the spread in the capabilities of culinary and pharmacological exploitation. Natural mushroom resources have become insufficient to meet the support needs. Therefore, traditional methods of extensive cultivation as well as modern technologies have been exploited to develop effective growing recommendations for dozens of economically important mushroom species. Mushrooms can decompose a wide range of organic materials, including organic waste. They play a fundamental role in nutrient cycling and exchange in the environment. The challenge is a proper substrate composition, including bio-fortified essential elements, and the application of growing conditions to enable a continuous supply of fruiting bodies of market quality and stabilized chemical composition. Many mushroom species are used for food preparation. Moreover, they are treated as functional foods, because they have health benefits beyond their nutritional value, and are used as natural medicines in many countries. Owing to the rapid development of mushroom farming, we reviewed the growing technologies used worldwide for mushroom species developed for food, processing, and pharmacological industries.

Regulation of glutamine synthetase activity by transcriptional and posttranslational modifications negatively influences ganoderic acid biosynthesis in Ganoderma lucidum

Glutamine synthetase (GS), a central nitrogen metabolic enzyme, plays important roles in the nitrogen regulation network and secondary metabolism in fungi. However, the mechanisms by which external nitrogen sources regulate fungal GS activity have not been determined. Here, we found that GS activity was inhibited under nitrate conditions in Ganoderma lucidum. By constructing gs-silenced strains and adding 1 mM GS inhibitor to inhibit GS activity, we found that a decrease in GS activity led to a decrease in ganoderic acid biosynthesis. The transcription of gs increased approximately five fold under nitrate conditions compared with that under ammonia. Electrophoretic mobility shift and yeast one-hybrid assay showed that gs was transcriptionally regulated by AreA. Although both gs expression and GS protein content increased under nitrate conditions, the GS activity still decreased. Treatment of recombinant GS with SIN-1 (protein nitration donor) resulted in a strengthened nitration accompanied by a 71% decrease in recombinant GS activity. Furthermore, intracellular GS could be nitrated from mycelia cultivated under nitrate conditions. These results indicated that GS activity could be inhibited by NO-mediated protein nitration. Our findings provide the first insight into the role of transcriptional and posttranslational regulation of GS activity in regulating secondary metabolism in fungi.

Enhancement of ganoderic acid production by promoting sporulation in a liquid static culture of Ganoderma species

Ganoderic acids (GAs) produced by Ganoderma are a type of lanostane-type triterpenoids with anticancer and antimetastatic activities; however, low production of GAs limits its wide application. In this study, a novel strategy by promoting sporulation of Ganoderma was developed to increase GA production. First, a high-spore producing Ganoderma strain G. 260125 was obtained from dikaryotic strain CGMCC 5.0026, and the sporulation-specific gene of this strain exhibits a higher transcription level than CGMCC 5.0026. Then, the effect of promoting sporulation on GA content was investigated. The maximum ganoderic acid (GA)-T, GA-Mk, and GA-Me contents in G. 260125 in shake flasks were 358.97, 78.32, and 12.75 μg/100 mg dry weight, respectively, which were 3.42, 2.91, and 1.73 times higher than those obtained in CGMCC 5.0026. Moreover, total and individual GA contents in spores were significantly higher than those in liquid static culture. Both concentrations of intermediates and transcription levels of GA biosynthetic genes also improved in G. 260125 during fermentation compared with those in CGMCC 5.0026. For scaling-up experiments, GA-T, GA-Me, and GA-Mk production in G. 260125 improved by 2.2-, 2.6-, and 2.1-fold compared with those in CGMCC 5.0026. In addition, the effectiveness of the developed strategy was also confirmed in three different Ganoderma strains. This work illustrated that promoting sporulation efficiently improves GA production in liquid static cultures of Ganoderma.

Optimization of ultrasonic-assisted extraction of polysaccharides and triterpenoids from the medicinal mushroom Ganoderma lucidum and evaluation of their in vitro antioxidant capacities

Ganoderma lucidum (Fr.) Krast, commonly known as "Lingzhi" in Chinese, is a medicinal mushroom that is rich in biologically active substances. Polysaccharides and triterpenoids are the two major components responsible for the bioactivity of this fungus. In the present study, the ultrasonic-assisted co-extraction (UACE) of polysaccharides and triterpenoids from G. lucidum was optimized using response surface methodology with a desirability function, with the equal importance for the two components. Following single factor experiments, the optimal conditions were determine as ultrasonic power of 210 W, extraction temperature of 80C, ratio of liquid to solid of 50 mL/g, and 100 min extraction time, using aqueous ethanol (50%, v/v) as the extracting solvent. Under the optimal conditions, the extraction yields of polysaccharides and triterpenoids reached 0.63% and 0.38%, respectively. On the basis of the scavenging capacity of 2,2-diphenyl-1-picrylhydrazyl and evaluation of reducing power, the antioxidant capacities of the polysaccharides obtained by optimal UACE process were higher than those of polysaccharides extracted using traditional hot water extraction, whereas the triterpenoid-rich extracts showed antioxidant activities similar to those obtained using the ethanol maceration method. The present study is the first report on the simultaneous extraction of polysaccharides and triterpenoids from G. lucidum. The developed UACE process could be useful in preparation of a polysaccharide- and triterpenoid-rich ingredient that holds great promise for application in the Ganoderma industry.

Ganoderma lucidum: A rational pharmacological approach to surmount cancer

ETHNOPHARMACOLOGICAL RELEVANCE

Ganoderma lucidum (G. lucidum) has been broadly used for health endorsement as well as longevity for over 2000 years in Asian countries. It is an example of an ancient remedy and known as immortality mushroom. It has been employed as a health promoting agent owing to its broad pharmacological and therapeutical approaches. It has been confirmed that G. lucidum exhibits significant potency to prevent and treat different types of cancers such as breast, prostate, colon, lung and cervical.

AIM OF THE STUDY

To explore anticancer effects of various pharmacologically active compounds obtained from G. lucidum and their possible mechanism of action.

MATERIALS AND METHODS

A literature search was conducted using PubMed, Goggle Scholar, Saudi Digital Library and Cochrane Library until October 11, 2019. Search was made by using keywords such as anticancer evidence, mechanism of action, pharmacology, antioxidant, toxicity, chemotherapy, triterpenoids and polysaccharides of G. lucidum.

RESULTS

Various chemical compounds from G. lucidum exhibit anticancer properties mainly through diverse mechanism such as cytotoxic properties, host immunomodulators, metabolizing enzymes induction, prohibit the expression of urokinase plasminogen activator (uPA) and urokinase plasminogen activator receptor (uPAR) in cancer cells. Among the various compounds of G. lucidum triterpenoids and polysaccharides are under the major consideration of studies due to their several evidence of preclinical and clinical studies against cancer.

CONCLUSION

Natural alternatives associated with mild side effects are the basic human need of present therapy to eradicate the new emerging disorders. This review is an attempt to compile pharmacologically active compounds of G. lucidum those exhibit anti cancer effects either alone or along with chemotherapy and anticancer mechanisms against various cancer cells, clinical trials, chemotherapy induced toxicity challenges with limitations. It acts as a possible substitute to combat cancer growth with advance and conventional combination therapies as natural alternatives.

Transcriptome dynamics and metabolite analysis revealed the candidate genes and regulatory mechanism of ganoderic acid biosynthesis during liquid superficial-static culture of Ganoderma lucidum

Ganoderic acid (GA), an important secondary metabolite of Ganoderma lucidum, exhibited many significant pharmacological activities. In this study, the biosynthetic mechanism of GAs was investigated by comparing metabolites and transcriptome dynamics during liquid superficial‐static culture (LSSC) and submerged culture (SC). LSSC was a better method to produce GA because thirteen GAs were identified from mycelia by UPLC‐QTOF‐MS, and the content of all GAs was higher in LSSC than in SC. Ergosterol was accumulated during the SC process in G. lucidum. Transcriptome dynamics analysis revealed CYP5150L8 was the key gene regulating lanosterol flux into GA biosynthesis. Other sixteen CYP450 genes were significantly higher expressed during the culture time in LSSC and could be potential candidate genes associated with the biosynthesis of different GAs. In addition, six of the ten expressed genes in ergosterol biosynthetic pathway shown upregulated at some time points in SC. These results not only provide a fundamental information of the key genes in ergosterol and GA biosynthetic pathway, but also provide directions for future elucidating the regulatory mechanisms of GAs in G. lucidum and enabling us to promote the development and utilization of LSSC at the industrial level.

Optimization of antioxidant, anti-diabetic, and anti-inflammatory activities and ganoderic acid content of differentially dried Ganoderma lucidum using response surface methodology

The dried Ganoderma lucidum (GL) has been widely used for its pharmacological properties and bioactive ganoderic acids (GAs). Herein, extraction procedures combining ultra-sonication and heating were optimized using response surface methodology based on four variables (antioxidant activity, anti-diabetic activity, total GAs content, and total polysaccharide content) and principal component analysis. The extraction of freeze-dried GL at temperatures between 64.2 and 70 °C for 1.2 h maximized the antioxidant activity and GA content, whereas the polysaccharide content and anti-diabetic activity were maximized by extraction between 66.8 and 70 °C for more than 2.8 h. Heat-dried GL extracted at 50 °C for 3 h provided the greatest anti-inflammatory activity against HaCaT cells by suppressing the response to inflammation related cytokines at mRNA levels. These results suggest that extraction conditions might be a limiting factor for target-oriented investigations, and optimized extraction methods may improve the potential effect and quality of harvested GL products.

Ganoderic acid A is the effective ingredient of Ganoderma triterpenes in retarding renal cyst development in polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common life-threatening monogenetic diseases characterized by progressive enlargement of fluid-filled renal cysts. Our previous study has shown that Ganoderma triterpenes (GT) retards PKD renal cyst development. In the present study we identified the effective ingredient of GT in suppression of kidney cyst development. Using an in vitro MDCK cystogenesis model, we identified ganoderic acid A (GA-A) as the most promising candidate among the 12 ganoderic acid (GA) monomers. We further showed that GA-A (6.25−100 μM) significantly inhibited cyst growth in MDCK cyst model and embryonic kidney cyst model in vitro, and the inhibitory effect was reversible. In kidney-specific Pkd1 knockout (kPKD) mice displaying severe cystic kidney disease, administration of GA-A (50 mg· kg⁻¹ ·d⁻¹, sc) significantly attenuated renal cyst development. In both MDCK cells and kidney of kPKD mice, we revealed that GA-A dose-dependently downregulated the Ras/MAPK signaling pathway. The expression of proliferating cell nuclear antigen (PCNA) was also suppressed, suggesting a possible effect of GA-A on cell proliferation. These experimental data suggest that GA-A may be the main ingredient of GT as a potential therapeutic reagent for treating ADPKD.

Function of ceramide synthases on growth, ganoderic acid biosynthesis and sphingolipid homeostasis in Ganoderma lucidum

Ceramide synthases (CERSs) catalyse an N-acyltransferase reaction using long-chain base (LCB) and fatty acyl-coenzyme A (CoA) as substrates to synthesize ceramide (Cer), which is the backbone of all complex sphingolipids. In the present study, three CERSs (LAG1, LAG2 and LAG3) form Ganoderma lucidum were analysed. The silencing of lag1 by RNA interference reduced ganoderic acid biosynthesis and Cer and complex sphingolipids contents, which contain long-chain-fatty-acids (LCFAs, including C16 and C18). In contrast, the silencing of lag2 or lag3 did not result in obvious phenotypic and sphingolipid homeostasis changes, although the lag2/lag3 double-silenced mutants exhibited increased ganoderic acid biosynthesis as well as reduced growth, reduced Cer and complex sphingolipids contents, which contain very-long-chain fatty acids (VLCFAs, including C22, C24 and C26). The results of the present study indicate that the three assayed CERSs have distinct physiological functions and substrate specificities in G. lucidum.

CRISPR-Cas9 assisted functional gene editing in the mushroom Ganoderma lucidum

The genetic manipulation of basidiomycete mushrooms is notoriously difficult and immature, and there is a lack of research reports on clustered regularly interspaced short palindromic repeat (CRISPR) based gene editing of functional genes in mushrooms. In this work, Ganoderma lucidum, a famous traditional medicinal basidiomycete mushroom, which produces a type of unique triterpenoid-anti-tumor ganoderic acids (GAs), was used, and a CRISPR/CRISPR-associated protein-9 nuclease (Cas9) editing system for functional genes of GA biosynthesis was constructed in the mushroom. As proof of concept, the effect of different gRNA constructs with endogenous u6 promoter and self-cleaving ribozyme HDV on ura3 disruption efficiency was investigated at first. The established system was applied to edit a cytochrome P450 monooxygenase (CYP450) gene cyp5150l8, which is responsible for a three-step biotransformation of lanosterol at C-26 to ganoderic acid 3-hydroxy-lanosta-8, 24-dien-26 oic acid. As a result, precisely edited cyp5150l8 disruptants were obtained after sequencing confirmation. The fermentation products of the wild type (WT) and cyp5150l8 disruptant were analyzed, and a significant decrease in the titer of four identified GAs was found in the mutant compared to WT. Another CYP gene involved in the biosynthesis of squalene-type triterpenoid 2, 3; 22, 23-squalene dioxide, cyp505d13, was also disrupted using the established CRISPR-Cas9 based gene editing platform of G. lucidum. The work will be helpful to strain molecular breeding and biotechnological applications of G. lucidum and other basidiomycete mushrooms.

Integrated Proteomics and Metabolomics Analysis Provides Insights into Ganoderic Acid Biosynthesis in Response to Methyl Jasmonate in Ganoderma Lucidum

Ganoderma lucidum is widely recognized as a medicinal basidiomycete. It was previously reported that the plant hormone methyl jasmonate (MeJA) could induce the biosynthesis of ganoderic acids (GAs), which are the main active ingredients of G. lucidum. However, the regulatory mechanism is still unclear. In this study, integrated proteomics and metabolomics were employed on G. lucidum to globally identify differences in proteins and metabolites under MeJA treatment for 15 min (M15) and 24 h (M24). Our study successfully identified 209 differential abundance proteins (DAPs) in M15 and 202 DAPs in M24. We also identified 154 metabolites by GC-MS and 70 metabolites by LC-MS in M24 that are involved in several metabolic pathways. With an in-depth analysis, we found some DAPs and metabolites that are involved in the oxidoreduction process, secondary metabolism, energy metabolism, transcriptional and translational regulation, and protein synthesis. In particular, our results reveal that MeJA treatment leads to metabolic rearrangement that inhibited the normal glucose metabolism, energy supply, and protein synthesis of cells but promoted secondary metabolites, including GAs. In conclusion, our proteomics and metabolomics data further confirm the promoting effect of MeJA on the biosynthesis of GAs in G. lucidum and will provide a valuable resource for further investigation of the molecular mechanisms of MeJA signal response and GA biosynthesis in G. lucidum and other related species.

Self-assembled thermal gold nanorod-loaded thermosensitive liposome-encapsulated ganoderic acid for antibacterial and cancer photochemotherapy

A novel nanoparticle (Au-LTSL-GA.A) uses the thermosensitive liposome (LTSL) to encapsulate ganoderic acid A (GA.A), which successfully transforms the polarity of GA.A and has excellent water solubility. The multifunctional Au-LTSL-GA.A, a self-assembled thermal nanomaterial, was used in antibacterial and anticancer applications in combination with near-infrared (NIR) irradiation. The designed Au-LTSL-GA.A nanoparticle was used as a nano-photosensitizer to achieve synergistic photochemotherapy based on the phototherapy sensitization property of Au nanorods (NRs) and antitumour activity of GA.A. In the antibacterial experiments, the Au-LTSL-GA.A + NIR irradiation had a broad-spectrum antibacterial effect, exhibiting a strong antibacterial activity against drug-resistant Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) compared with the raw GA.A and LTSL-GA.A. In the anticancer experiments, Au-LTSL-GA.A + NIR irradiation, which combined phototherapy sensitization property of Au NRs with antitumour activity of GA.A, exhibited high anticancer activity against MCF-7 cells. The IC50 value of Au-LTSL-GA.A + NIR irradiation (12.1 ± 1.3 μg/mL) was almost similar to cisplatin in MCF-7 cells. The evaluation of the potential in vivo toxicity of Au-LTSL-GA.A revealed no toxicity in mice. The results of this study suggest that Au-LTSL-GA.A has a wide range of potential industrial and clinical applications, such as in antibacterial treatment and cancer photochemotherapy.

Enhanced production of individual ganoderic acids by integrating Vitreoscilla haemoglobin expression and calcium ion induction in liquid static cultures of Ganoderma lingzhi

Ganoderic acids produced by Ganoderma exhibit anticancer and antimetastatic activities. A novel approach by combining Vitreoscilla haemoglobin (VHb) expression and calcium ion induction was developed to enhance ganoderic acid (GA) production in liquid static cultures of G. lingzhi. The maximum contents of GA-O, GA-S and GA-Me were 1451.33 ± 67.50, 1431.23 ± 79.74 and 1283.81 ± 85.13 μg per 100 mg cell weight, respectively under the integrated approach, which are the highest contents as ever reported in Ganoderma. The contents of squalene and lanosterol were increased by 2.0- and 3.0-fold in this case compared with those in the control. The transcription levels of 3-hydroxy-3-methylglutaryl coenzyme A reductase, farnesyl-diphosphate synthase, squalene synthase and cytochrome P450 CYP5150L8 were upregulated by 2.56-, 3.31-, 2.59- and 6.12-fold respectively. Additionally, the expression of VHb improved the ratio of type I to type II GA in liquid static cultivation of G. lingzhi. The transcription levels of cyp512a2, cyp512v2 and cyp512a13, candidate cytochrome P450 genes involved in oxidative modification of the lanostane skeleton in GA biosynthesis, were also increased by 2.28-, 2.65- and 3.54-fold in the VHb-expressing strain respectively. Our results illustrated that the approach described here efficiently improved GA production in G. lingzhi fermentation.

A Genome-Centric Approach Reveals a Novel Glycosyltransferase from the GA A07 Strain of Bacillus thuringiensis Responsible for Catalyzing 15-O-Glycosylation of Ganoderic Acid A

Strain GA A07 was identified as an intestinal Bacillus bacterium of zebrafish, which has high efficiency to biotransform the triterpenoid, ganoderic acid A (GAA), into GAA-15-O-β-glucoside. To date, only two known enzymes (BsUGT398 and BsUGT489) of Bacillus subtilis ATCC 6633 strain can biotransform GAA. It is thus worthwhile to identify the responsible genes of strain GA A07 by whole genome sequencing. A complete genome of strain GA A07 was successfully assembled. A phylogenomic analysis revealed the species of the GA A07 strain to be Bacillus thuringiensis. Forty glycosyltransferase (GT) family genes were identified from the complete genome, among which three genes (FQZ25_16345, FQZ25_19840, and FQZ25_19010) were closely related to BsUGT398 and BsUGT489. Two of the three candidate genes, FQZ25_16345 and FQZ25_19010, were successfully cloned and expressed in a soluble form in Escherichia coli, and the corresponding proteins, BtGT_16345 and BtGT_19010, were purified for a biotransformation activity assay. An ultra-performance liquid chromatographic analysis further confirmed that only the purified BtGT_16345 had the key biotransformation activity of catalyzing GAA into GAA-15-O-β-glucoside. The suitable conditions for this enzyme activity were pH 7.5, 10 mM of magnesium ions, and 30 °C. In addition, BtGT_16345 showed glycosylation activity toward seven flavonoids (apigenein, quercetein, naringenein, resveratrol, genistein, daidzein, and 8-hydroxydaidzein) and two triterpenoids (GAA and antcin K). A kinetic study showed that the catalytic efficiency (kcat/KM) of BtGT_16345 was not significantly different compared with either BsUGT398 or BsUGT489. In short, this study identified BtGT_16345 from B. thuringiensis GA A07 is the catalytic enzyme responsible for the 15-O-glycosylation of GAA and it was also regioselective toward triterpenoid substrates.

High Oxygen Treatments Enhance the Contents of Phenolic Compound and Ganoderic Acid, and the Antioxidant and DNA Damage Protective Activities of Ganoderma lingzhi Fruiting Body

Ganoderma lingzhi is a famous medicinal mushroom used as Chinese medicine or functional food and has been accepted across the globe. It is important to enhance the contents of bioactive compounds, which in turn improves the quality and biological activity of G. lingzhi fruiting body. In this work, freshly harvested G. lingzhi fruiting bodies were treated continuously with air or with 60 and 80% oxygen for 6 days. Samples were collected and determined initially and at 1 day interval during treatment. A high total ganoderic acid content of 29.44 g kg^–1 was obtained in samples treated with 60% oxygen at day 3. Quantitative reverse transcriptase (qRT)-PCR and high-performance liquid chromatography (HPLC) analysis showed that the expression levels of hydroxymethylglutaryl-CoA synthase, squalene synthase, and oxidosqualene cyclase genes were substantially increased, resulting in the increase of ganoderic acids A, B, and C2 and ganoderenic acid B. The scavenging activities with 1,1-diphenyl-2-picrylhydrazyl radical, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical, hydroxyl radical, and superoxide radical and the DNA damage protective activity were also enhanced by high oxygen treatment. The results of this work provided a potential method to enhance the active metabolite synthesis in the fruiting body of G. lingzhi.

A New Triterpenoid Glucoside from a Novel Acidic Glycosylation of Ganoderic Acid A via Recombinant Glycosyltransferase of Bacillus subtilis

Ganoderic acid A (GAA) is a bioactive triterpenoid isolated from the medicinal fungus Ganoderma lucidum. Our previous study showed that the Bacillus subtilis ATCC (American type culture collection) 6633 strain could biotransform GAA into compound (1), GAA-15-O-β-glucoside, and compound (2). Even though we identified two glycosyltransferases (GT) to catalyze the synthesis of GAA-15-O-β-glucoside, the chemical structure of compound (2) and its corresponding enzyme remain elusive. In the present study, we identified BsGT110, a GT from the same B. subtilis strain, for the biotransformation of GAA into compound (2) through acidic glycosylation. BsGT110 showed an optimal glycosylation activity toward GAA at pH 6 but lost most of its activity at pH 8. Through a scaled-up production, compound (2) was successfully isolated using preparative high-performance liquid chromatography and identified to be a new triterpenoid glucoside (GAA-26-O-β-glucoside) by mass and nuclear magnetic resonance spectroscopy. The results of kinetic experiments showed that the turnover number (k_cat) of BsGT110 toward GAA at pH 6 (k_cat = 11.2 min⁻¹) was 3-fold higher than that at pH 7 (k_cat = 3.8 min⁻¹), indicating that the glycosylation activity of BsGT110 toward GAA was more active at acidic pH 6. In short, we determined that BsGT110 is a unique GT that plays a role in the glycosylation of triterpenoid at the C-26 position under acidic conditions, but loses most of this activity under alkaline ones, suggesting that acidic solutions may enhance the catalytic activity of this and similar types of GTs toward triterpenoids.

Increased production of ganoderic acids by overexpression of homologous farnesyl diphosphate synthase and kinetic modeling of ganoderic acid production in Ganoderma lucidum

Background

Ganoderic acids (GAs), derived from the medicinal mushroom Ganoderma lucidum, possess anticancer and other important pharmacological activities. To improve production of GAs, a homologous farnesyl diphosphate synthase (FPS) gene was overexpressed in G. lucidum. Moreover, the influence of FPS gene overexpression on GA production was investigated by developing the corresponding mathematical models.

Results

The maximum levels of total GAs and individual GAs (GA-T, GA-S, and GA-Me) in the transgenic strain were 2.76 mg/100 mg dry weight (DW), 41 ± 2, 21 ± 5, and 28 ± 1 μg/100 mg DW, respectively, which were increased by 2.28-, 2.27-, 2.62-, and 2.80-folds compared with those in the control. Transcription levels of squalene synthase (SQS) and lanosterol synthase (LS) genes during GA biosynthesis were upregulated by 2.28- and 1.73-folds, respectively, in the transgenic G. lucidum. In addition, the developed unstructured models had a satisfactory fit for the process of GA production in submerged cultures of G. lucidum. Analysis of the kinetic process showed that FPS gene overexpression had a stronger positive impact on GA production compared with its influence on cell growth. Also, FPS gene overexpression led to a higher non-growth-associated-constant β (1.151) over the growth-associated-constant α (0.026) in the developed models.

Conclusions

FPS gene overexpression is an effective strategy to improve the production of GAs in G. lucidum. The developed mathematical models are useful for developing a better GA production process in future large-scale bioreactors.

Electronic supplementary material

The online version of this article (10.1186/s12934-019-1164-3) contains supplementary material, which is available to authorized users.

Enhanced Ganoderic Acids Accumulation and Transcriptional Responses of Biosynthetic Genes in Ganoderma lucidum Fruiting Bodies by Elicitation Supplementation

Ganoderic acids (GAs) are a type of highly oxygenated lanostane-type triterpenoids that are responsible for the pharmacological activities of Ganoderma lucidum. They have been investigated for their biological activities, including antibacterial, antiviral, antitumor, anti-HIV-1, antioxidation, and cholesterol reduction functions. Inducer supplementation is viewed as a promising technology for the production of GAs. This study found that supplementation with sodium acetate (4 mM) significantly increased the GAs content of fruiting bodies by 28.63% compared to the control. In order to explore the mechanism of ganoderic acid accumulation, the transcriptional responses of key GAs biosynthetic genes, including the acetyl coenzyme A synthase gene, and the expression levels of genes involved in calcineurin signaling and acetyl-CoA content have been analyzed. The results showed that the expression of three key GAs biosynthetic genes (hmgs, fps, and sqs) were significantly up-regulated. Analysis indicated that the acetate ion increased the expression of genes related to acetic acid assimilation and increased GAs biosynthesis, thereby resulting in the accumulation of GAs. Further investigation of the expression levels of genes involved in calcineurin signaling revealed that Na⁺ supplementation and the consequent exchange of Na⁺/Ca²⁺ induced GAs biosynthesis. Overall, this study indicates a feasible new approach of utilizing sodium acetate elicitation for the enhanced production of valuable GAs content in G. lucidum, and also provided the primary mechanism of GAs accumulation.

Interdependent nitric oxide and hydrogen peroxide independently regulate the coix seed oil-induced triterpene acid accumulation in Ganoderma lingzhi

Recent progress has been made in adding exogenous vegetable oils in culture media to promote bioactive metabolite production in several medicinal mushrooms, but the mechanism is still unclear. In this study, we found that the vegetable oil coix seed oil (CSO) could induce the biosynthesis of triterpene acids (TAs) and also significantly increase cytoplasmic nitric oxide (NO) and hydrogen peroxide (H₂O₂) concentrations in the mycelium of Ganoderma lingzhi. The change in TA biosynthesis caused by CSO could be reversed by adding NO scavenger or H₂O₂ scavenger, and adding NO scavenger or H₂O₂ scavenger resulted in the reduction of the cytoplasmic H₂O₂ or NO concentration under CSO treatment, respectively. Moreover, adding NO scavenger or H₂O₂ scavenger reversed TA biosynthesis, which could be rescued by H₂O₂ or NO donor, respectively. Taken together, our study indicated that both NO and H₂O₂ were involved in the regulation of TA biosynthesis, and CSO-activated NO and H₂O₂ were interdependent but independently regulated the TA biosynthesis under CSO treatment in G. lingzhi.

Optimization of Ganoderma lucidum Polysaccharides Fermentation Process for Large-Scale Production

The objective of this study was to increase the intracellular polysaccharide yield of Ganoderma lucidum. The accordingly optimized fermentation medium by central composite design method contains glucose 40 g L^-1, yeast powder 12 g L^-1, potassium dihydrogen phosphate 3 g L^-1, initial pH 5.5, and inoculum size 10 mL 100 mL^-1. Under this condition, the predicted value of intracellular polysaccharide yield was 2.03 g L^-1. Shake flask experiments confirmed that the average intracellular polysaccharide yield was 1.98 g L^-1 similar to the predicted value. The yields of intracellular polysaccharides in the 5-L and 50-L fermentors were 2.59 g L^-1 and 2.65 g L^-1, respectively. The molecular weight distribution of intracellular and extracellular polysaccharides obtained was determined by HPSEC-MALLS-RI. The results showed that the weight-average molecular weight of component 1 in the intracellular crude polysaccharide was 4.695 × 10⁶ Da and the mass fraction was 58%. The weight-average molecular weight of component 2 in the extracellular polysaccharide was 5.554 × 10⁴ Da. The mass fraction was 94.9%. The liquid submerged fermentation process of G. lucidum mycelium obtained from this study has effectively increased the yield of intracellular polysaccharides. Its intracellular and extracellular polysaccharides have good immunological activity. Conceivably, the optimized process can be applied for the large-scale production.