A new approach for improving cordycepin productivity in surface liquid culture ofCordyceps militarisusing high-energy ion beam irradiation

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.

Enhancement of cordycepin production from Cordyceps militaris culture by epigenetic modification

Cordycepin (3'-deoxyadenosine) is a nucleoside analogue and biosynthesised by Cordyceps militaris, an entomopathogenic fungus. In this study, an epigenetic modifier was applied to static liquid cultures to enhance cordycepin production. C. militaris was cultured in a static liquid culture, and valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, was supplemented in order to modifying the epigenetic status. Gene regulatory network was explored to understand the molecular mechanisms underlying cordycepin production. 50 micromolar of VPA enhanced cordycepin production by 41.187% via the upregulation of 5'-nucleotidase, adenylate kinase, phosphorybosyltransferase, Cns1, Cns2, Cnsa3, and Cns4 of C. militaris for at least 2 days after VPA treatment. The maximum production of cordycepin was 2,835.32 ± 34.35 mg/L in 400 mL-working volume. A scaled-up culture was established with a working volume of 10 L, which led to the slight decrease of cordycepin production. This might due to multifactorial effects, for instance limited aeration and an uneven dispersion of nutrients in the culture system. This scaled-up culture was still needed further optimization. The modification of epigenetic status by VPA significantly enhanced cordycepin production by altering key gene regulatory network of C. militaris. The strategy established in this study might be applicable to other microorganism culture in order to improving the production of bioactive compounds. This work aimed to enhance the production of cordycepin by modifying the epigenetic status of C. militaris, in which subsequently altered gene regulatory network of cordycepin biosynthesis pathway. The weekly supplementation of valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, significantly improve cordycepin production over 40%, compared to the untreated control, and the gene regulatory network of C. militaris was also adapted.

Improvement of cordycepin production by an isolated Paecilomyces hepiali mutant from combinatorial mutation breeding and medium screening

Cordycepin is a major bioactive compound found in Cordyceps sinensis that exhibits a broad spectrum of biological activities. Here a Paecilomyces hepiali OR-1 strain was initially isolated from plateau soil for the bioproduction of cordycepin. Subsequently, strain modification including ⁶⁰Co γ-ray and ultraviolet irradiation were employed to increase the cordycepin titer, resulted in a high-yield mutant strain P. hepiali ZJB18001 with the cordycepin content of 0.61 mg/g_DCW, showing a 2.3-fold to that from the wild strain (0.26 mg/g_DCW). Furthermore, medium screening based on Box-Behnken design and the response surface methodology facilitated the enhancement of cordycepin yield to the value of 0.96 mg/g_DCW at 25 °C for 5 days in submerged cultivation with an optimized medium composition. The high cordycepin yield, rapid growth rate and stable genetic characteristics of P. hepiali ZJB18001 are beneficial in terms of costs and time for the industrialization of cordycepin production.

Effects of Cordycepin in Cordyceps militaris during Its Infection to Silkworm Larvae

Cordyceps militaris produces cordycepin, a secondary metabolite that exhibits numerous bioactive properties. However, cordycepin pharmacology in vivo is not yet understood. In this study, the roles of cordycepin in C. militaris during its infection were investigated. After the injection of conidia, C. militaris NBRC100741 killed silkworm larvae more rapidly than NBRC103752. At 96 and 120 h, Cmcns genes (Cmcns1-4), which are part of the cordycepin biosynthesis gene cluster, were expressed in fat bodies and cuticles. Thus, cordycepin may be produced in the infection of silkworm larvae. Further, cordycepin enhanced pathogenicity toward silkworm larvae of Metarhizium anisopliae and Beauveria bassiana, that are also entomopathogenic fungi and do not produce cordycepin. In addition, by RNA-seq analysis, the increased expression of the gene encoding a lipoprotein 30K-8 (Bmlp20, KWMTBOMO11934) and decreased expression of genes encoding cuticular proteins (KWMTBOMO13140, KWMTBOMO13167) and a serine protease inhibitor (serpin29, KWMTBOMO08927) were observed when cordycepin was injected into silkworm larvae. This result suggests that cordycepin may aid the in vivo growth of C. militaris in silkworm larvae by the influence of the expression of some genes in silkworm larvae.

Screening of Beauveria bassiana with high biocontrol potential based on ARTP mutagenesis and high-throughput FACS

Beauveria bassiana is a promising biocontrol agent due to its entomopathogenic activities and residue-free characteristics. However, its susceptibility to abiotic stresses and naturally low virulence limit the effective application of this fungus. To effectively obtain fungal strains with high biocontrol potential, fluorescence-activated cell sorting (FACS) was used to screen mutant libraries generated by atmospheric and room temperature plasma (ARTP). Among about 8000 mutants obtained by ARTP mutagenesis, six candidate mutants were selected according to the forward scatter (FSC) signal readings of FACS. B6, with a 37.4% higher FSC reading than wild-type (WT), showed a 32.6% increase in virulence. It also presented a 13.5% decrease in median germinating time (GT₅₀) and a 12.1% increase in blastospore production. Comparative analysis between insect transcriptional responses to B6 and WT infection showed that the immune response coupled with protein digestion and absorption progress was highly activated in B6-infected Galleria mellonella larvae, while fatty acid synthesis was suppressed after 3 days of infection. Our results confirmed the feasibility of sorting B. bassiana with high biocontrol potential via the combination of ARTP and FACS and facilitated the understanding of insect-pathogen interactions, highlighting a new strategy for modifying entomopathogenic fungi to improve the efficiency of biological control.

Characterization and inhibition of four fungi producing citrinin in various culture media

PURPOSE

This study aimed to investigate the effects of different fermentation conditions (culture medium, temperature, incubation time, pH value and additive) on citrinin production by four fungi.

RESULTS

Among the culture media, potato dextrose medium had lowest citrinin production, followed by yeast sucrose medium and monosodium glutamate medium. The lowest citrinin contents were produced by Monascus anka (M. anka) in potato dextrose medium and yeast sucrose medium, Aspergillus oryzae AS3.042 (A. oryzae) produced the lowest citrinin production in monosodium glutamate medium. The optimum fermentation temperatures for citrinin production by Aspergillus niger (A. niger) and Penicillium citrinum (P. citrinum) were at 30 °C, whereas those by M. anka and A. oryzae were at 35 °C. Citrinin synthesis by four fungi were completely inhibited with a pH value of less than 5.4. By adding ethylene diamine tetraacetic acid (EDTA) or triammonium citrate into monosodium glutamate medium, citrinin production by A. oryzae and A. niger were totally inhibited. Ammonium sulfate completely inhibited citrinin production by A. oryzae, M. anka and P. citrinum, and ammonium nitrate completely inhibited citrinin production by A. oryzae.

CONCLUSIONS

These results indicated that the suitable fermentation conditions could make considerable contributions to the reduction of citrinin production. This study provided an effective way for decreasing the citrinin production.

Synthesis of cordycepin: Current scenario and future perspectives

Cordyceps genus, such as C. militaris and C. kyushuensis, is a source of a rare traditional Chinese medicine that has been used for the treatment of numerous chronic and malignant diseases. Cordycepin, 3'-deoxyadenosine, is a major active compound found in most Cordyceps. Cordycepin exhibits a variety of biological activities, including anti-tumor, immunomodulation, antioxidant, and anti-aging, among others, which could be applied in health products, medicine, cosmeceutical etc. fields. This review focuses on the synthesis methods for cordycepin. The current methods for cordycepin synthesis involve chemical synthesis, microbial fermentation, in vitro synthesis and biosynthesis; however, some defects are unavoidable and the production is still far from the demand of cordycepin. For the future study of cordycepin synthesis, based on the illumination of cordycepin biosynthesis pathway, genetical engineering of the Cordyceps strain or introducing microbes by virtue of synthetic biology will be the great potential strategies for cordycepin synthesis. This review will aid the future synthesis of the valuable cordycepin.

Molecular characterization of proton beam-induced mutations in soybean using genotyping-by-sequencing

Proton beam irradiation is a next-generation technique to develop mutant crop varieties. The mutagenic effects and molecular mechanisms of radiation are important multi-disciplinary research subjects. This study was conducted to investigate the types of mutations induced in the soybean genome by proton beam irradiation. In total, 22 plants, including 10 M2 plants treated with proton beam irradiation at 118 and 239 Gy, each, and two wild-type plants (Daepung) were sequenced by genotyping-by-sequencing (GBS). In total, 7453 single nucleotide polymorphisms (SNPs) were detected in the 20 M2 plants, compared with the two wild-type controls. The SNP frequency was 1/36,976 bp with proton beam irradiation at 118 Gy, and 1/32,945 bp at 239 Gy. Of these, 3569 SNPs were detected in genic regions. We observed that proton beam irradiation induced more substitutions than small insertion-deletions (INDELs). Based on the mutagenic effect of proton beam irradiation, the frequency of transition mutations was shown to be higher than that of transversions. The proton beam-induced SNPs were distributed uniformly in most of the chromosomes. Gene ontology (GO) analysis showed that there were many genes involved in protein metabolic process under biological process, intracellular membrane-bounded organelle under cellular component, and nucleic acid binding under molecular function. This study could provide valuable information for investigating the potential mechanisms of mutation, and guidance for developing soybeans cultivars using mutation breeding.

Uncovering global metabolic response to cordycepin production in Cordyceps militaris through transcriptome and genome-scale network-driven analysis

The cellular metabolic adaptations of Cordyceps militaris have been progressively studied. In particular, the cordycepin pathway is of interest in medicinal applications. Even though the metabolic pathways for cordycepin production are known to be related to different carbon sources, the regulatory mechanisms at a systems level are poorly characterized. To explore the regulatory mechanisms, this study therefore aimed to investigate the global metabolic response to cordycepin production in C. militaris through transcriptome analysis and genome-scale network-driven analysis. Here, transcriptome analysis of 16,805 expressed genes in C. militaris strain TBRC6039 grown on different carbon sources was performed. Of these genes, 2,883 were significantly differentially expressed genes, uncovering sucrose- and glucose-mediated changes in the transcriptional regulation of central carbon metabolism in C. militaris, which was shown using the CmSNF1 mechanism as an example. After applying genome-scale metabolic network-driven analysis, reporter metabolites and key metabolic subnetworks involving adenosine, cordycepin and methionine were proposed through the up-regulation of cordycepin biosynthetic genes. Our findings suggest that the transcriptional regulation of these pathways is a ubiquitous feature in response to specific culture conditions during cordycepin overproduction.

Insight into cordycepin biosynthesis of Cordyceps militaris: Comparison between a liquid surface culture and a submerged culture through transcriptomic analysis

Cordyceps militaris produces cordycepin, which is known to be a bioactive compound. Currently, cordycepin hyperproduction of C. militaris was carried out in a liquid surface culture because of its low productivity in a submerged culture, however the reason was not known. In this study, 4.92 g/L of cordycepin was produced at the 15^th day of C. militaris NBRC 103752 liquid surface culture, but only 1 mg/L was produced in the submerged culture. RNA-Seq was used to clarify the gene expression profiles of the cordycepin biosynthetic pathways of the submerged culture and the liquid surface culture. From this analysis, 1036 genes were shown to be upregulated and 557 genes were downregulated in the liquid surface culture compared with the submerged culture. Specifically, adenylosuccinate synthetase and phosphoribosylaminoimidazole-succinocarboxamide (SAICAR) synthase in purine nucleotide metabolism were significantly upregulated in the liquid surface culture. Thick mycelia formation in the liquid surface culture was found to induce the expression of hypoxia-related genes (GABA shunt, glutamate synthetase precursor, and succinate-semialdehyde dehydrogenase). Cytochrome P450 oxidoreductases containing heme were also found to be significantly enriched, suggesting that a hypoxic condition might be created in the liquid surface culture. These results suggest that hypoxic conditions are more suitable for cordycepin production in the liquid surface culture compared with the submerged culture. Our analysis paves the way for unraveling the cordycepin biosynthesis pathway and for improving cordycepin production in C. militaris.

Optimal conditions for cordycepin production in surface liquid-cultured Cordyceps militaris treated with porcine liver extracts for suppression of oral cancer

Cordycepin is one of the most crucial bioactive compounds produced by Cordyceps militaris and has exhibited antitumor activity in various cancers. However, industrial production of large amounts of cordycepin is difficult. The porcine liver is abundant in proteins, vitamins, and adenosine, and these ingredients may increase cordycepin production and bioconversion during C. militaris fermentation. We observed that porcine liver extracts increased cordycepin production. In addition, air supply (2 h/d) significantly increased the cordycepin level in surface liquid-cultured C. militaris after 14 days. Moreover, blue light light-emitting diode irradiation (16 h/d) increased cordycepin production. These findings indicated that these conditions are suitable for increasing cordycepin production. We used these conditions to obtain water extract from the mycelia of surface liquid-cultured C. militaris (WECM) and evaluated the anti-oral cancer activity of this extract in vitro and in vivo. The results revealed that WECM inhibited the cell viability of SCC-4 oral cancer cells and arrested the cell cycle in the G2/M phase. Oxidative stress and mitochondrial dysfunction (mitochondrial fission) were observed in SCC-4 cells treated with WECM for 12 hours. Furthermore, WECM reduced tumor formation in 7,12-dimethylbenz[a]anthracene-induced hamster buccal pouch carcinogenesis through the downregulation of proliferating cell nuclear antigen, vascular endothelial growth factor, and c-fos expression. The results indicated that porcine liver extracts irradiated with blue light light-emitting diode and supplied with air can be used as a suitable medium for the growth of mycelia and production of cordycepin, which can be used in the treatment of oral cancer.

Simple and efficient isolation of cordycepin from culture broth of a Cordyceps militaris mutant

Isolation of cordycepin from the culture broth of Cordyceps militaris mutant was investigated. Based on the solubility curve, three crystallizing processes, temperature shift (process I), pH shift (process II), and pH shift followed by temperature shift (process III) were carried out. Process III was the most promising method regarding both purity and yield.

Optimization of large-scale culture conditions for the production of cordycepin with Cordyceps militaris by liquid static culture

Cordycepin is one of the most important bioactive compounds produced by species of Cordyceps sensu lato, but it is hard to produce large amounts of this substance in industrial production. In this work, single factor design, Plackett-Burman design, and central composite design were employed to establish the key factors and identify optimal culture conditions which improved cordycepin production. Using these culture conditions, a maximum production of cordycepin was 2008.48 mg/L for 700 mL working volume in the 1000 mL glass jars and total content of cordycepin reached 1405.94 mg/bottle. This method provides an effective way for increasing the cordycepin production at a large scale. The strategies used in this study could have a wide application in other fermentation processes.

Optimization of fermentation conditions and purification of cordycepin from Cordyceps militaris

The fermentation medium and conditions for the production of cordycepin were optimized in static culture using single-factor experiments, Placket-Burman design, a central composite design, and response surface methodology. Among seven variables including temperature, pH, and the concentrations of glucose, tryptone, yeast extract, KH₂PO₄, and MgSO₄ · 7H₂O, temperature and the concentrations of yeast extract and tryptone were found to be the important factors that significantly affected cordycepin production. The optimized medium consisted of yeast extract 9.00 g/L and tryptone 17.10 g/L, while the optimized culture conditions consisted of seed age 3 days, with an inoculum size of 10% and incubation temperature of 27.1°C. A maximum cordycepin yield of 7.35 g/L was achieved in a 5-L fermenter under the optimized conditions. Next, cordycepin was partially purified and determined. The resulting product showed 90.54% high-performance liquid chromatography (HPLC)-ultraviolet (UV) purity. Therefore, cordycepin was applied to a cell viability assay on SH-SY5Y cells and RM-1 cells. Cordycepin can inhibit the proliferation of RM-1 cells with IC₅₀ of 133 µmol/L, but it has no inhibitory effect on SH-SY5Y cells. Supplemental materials are available for this article.

Extract of Cordyceps militaris inhibits angiogenesis and suppresses tumor growth of human malignant melanoma cells

Angiogenesis is essential for tumor development and metastasis. Among several angiogenic factors, vascular endothelial growth factor receptor (VEGF) is important for tumor-derived angiogenesis and commonly overexpressed in solid tumors. Thus, many antitumor strategies targeting VEGF have been developed to inhibit cancer angiogenesis, offering insights into the successful treatment of solid cancers. However, there are a number of issues such as harmful effects on normal vascularity in clinical trials. Taking this into consideration, we employed Cordyceps militaris as an antitumor approach due to its biological safety in vivo. The herbal medicinal mushroom Cordyceps militaris has been reported to show potential anticancer properties including anti-angiogenic capacity; however, its concrete properties have yet to be fully demonstrated. In this study, we aimed to elucidate the biological role of Cordyceps militaris extract in tumor cells, especially in regulating angiogenesis and tumor growth of a human malignant melanoma cell line. We demonstrated that Cordyceps militaris extract remarkably suppressed tumor growth via induction of apoptotic cell death in culture that links to the abrogation of VEGF production in melanoma cells. This was followed by mitigation of Akt1 and GSK-3β activation, while p38α phosphorylation levels were increased. Extract treatment in mouse model xenografted with human melanoma cells resulted in a dramatic antitumor effect with down-regulation of VEGF expression. The results suggest that suppression of tumor growth by Cordyceps militaris extract is, at least, mediated by its anti-angiogenicity and apoptosis induction capacities. Cordyceps militaris extract may be a potent antitumor herbal drug for solid tumors.

Pharmacological and therapeutic potential of Cordyceps with special reference to Cordycepin

An entomopathogenic fungus, Cordyceps sp. has been known to have numerous pharmacological and therapeutic implications, especially, in terms of human health making it a suitable candidate for ethno-pharmacological use. Main constituent of the extract derived from this fungus comprises a novel bio-metabolite called as Cordycepin (3′deoxyadenosine) which has a very potent anti-cancer, anti-oxidant and anti-inflammatory activities. The current review discusses about the broad spectrum potential of Cordycepin including biological and pharmacological actions in immunological, hepatic, renal, cardiovascular systems as well as an anti-cancer agent. The article also reviews the current efforts to delineate the mechanism of action of Cordycepin in various bio-molecular processes. The study will certainly draw the attention of scientific community to improve the bioactivity and production of Cordycepin for its commercial use in pharmacological and medical fields.

Genome-wide transcriptome and proteome analysis on different developmental stages of Cordyceps militaris

BACKGROUND

Cordyceps militaris, an ascomycete caterpillar fungus, has been used as a traditional Chinese medicine for many years owing to its anticancer and immunomodulatory activities. Currently, artificial culturing of this beneficial fungus has been widely used and can meet the market, but systematic molecular studies on the developmental stages of cultured C. militaris at transcriptional and translational levels have not been determined.

METHODOLOGY/PRINCIPAL FINDINGS

We utilized high-throughput Illumina sequencing to obtain the transcriptomes of C. militaris mycelium and fruiting body. All clean reads were mapped to C. militaris genome and most of the reads showed perfect coverage. Alternative splicing and novel transcripts were predicted to enrich the database. Gene expression analysis revealed that 2,113 genes were up-regulated in mycelium and 599 in fruiting body. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed to analyze the genes with expression differences. Moreover, the putative cordycepin metabolism difference between different developmental stages was studied. In addition, the proteome data of mycelium and fruiting body were obtained by one-dimensional gel electrophoresis (1-DGE) coupled with nano-electrospray ionization liquid chromatography tandem mass spectrometry (nESI-LC-MS/MS). 359 and 214 proteins were detected from mycelium and fruiting body respectively. GO, KEGG and Cluster of Orthologous Groups (COG) analysis were further conducted to better understand their difference. We analyzed the amounts of some noteworthy proteins in these two samples including lectin, superoxide dismutase, glycoside hydrolase and proteins involved in cordycepin metabolism, providing important information for further protein studies.

CONCLUSIONS/SIGNIFICANCE

The results reveal the difference in gene expression between the mycelium and fruiting body of artificially cultivated C. militaris by transcriptome and proteome analysis. Our study provides an effective resource for the further developmental and medicinal research of this promising fungus.

The genus Cordyceps: a chemical and pharmacological review

Objectives

Natural remedies are becoming increasingly popular and important in the public and scientific communities. Historically, natural remedies have been shown to present interesting biological and pharmacological activity and are used as chemotherapeutic agents. For centuries Cordyceps, which is a genus of more than 400 species in the family Clavicipitaceae, has been used in traditional Chinese medicine. This study highlights the chemistry and pharmacology of Cordyceps, especially Cordyceps sinensis (Berk.) Sacc. and C. militaris (Fr.) L. Information was obtained from Google Scholar and the journal databases PubMed and Scopus.

Key findings

Many bioactive components of Cordyceps have been extracted, such as cordycepin, cordycepic acid, ergosterol, polysaccharides, nucleosides and peptides. Studies show that Cordyceps and its active principles possess a wide range of pharmacological actions, such as anti-inflammatory, antioxidant, antitumour, antihyperglycaemic, antiapoptosis, immunomodulatory, nephroprotective, and hepatoprotective.

Summary

More research is required to discover the full extent of the activity of Cordyceps.

Medicinal uses of the mushroom Cordyceps militaris: current state and prospects

Cordyceps militaris is a potential harbour of bio-metabolites for herbal drugs and evidences are available about its applications for revitalization of various systems of the body from ancient times. Amongst all the species, C. militaris is considered as the oldest source of some useful chemical constituents. Besides their popular applications for tonic medicine by the all stairs of the community, the constituents of C. militaris are now used extensively in modern systems of medicine. The current survey records the mysterious potentials of C. militaris are boosting up the present herbal treatments, as well as gearing up the green pharmacy revolution, in order to create a friendly environment with reasonable safety. Evidence showed that the active principles of C. militaris are beneficial to act as pro-sexual, anti-inflammatory, anti-oxidant/anti-aging, anti-tumour/anti-cancer/anti-leukemic, anti-proliferative, anti-metastatic, immunomodulatory, anti-microbial, anti-bacterial, anti-viral, anti-fungal, anti-protozoal, insecticidal, larvicidal, anti-fibrotic, steroidogenic, hypoglacaemic, hypolipidaemic, anti-angiogenetic, anti-diabetic, anti-HIV, anti-malarial, anti-fatigue, neuroprotective, liver-protective, reno-protective as well as pneumo-protective, let alone their other synergistic activities, which let it be marketable in the western countries as over-the-counter medicine. A number of culture techniques for this mushroom have been noticed, for example, storage/stock culture, pre-culture, popular/indigenous culture (spawn culture, husked rice culture and saw dust culture) and, special/laboratory culture (shaking culture, submerged culture, surface liquid culture and continuous/repeated batch culture). The prospects for herbal biotechnology regarding drug discovery using C. militaris delivering what it has promised are high, as the technology is now extremely more powerful than before. This study chiefly highlights the medicinal uses of the mushroom C. militaris including its culture techniques, also aiming to draw sufficient attention of the researchers to the frontier research needs in this context.