Effect of oxygen supply on biomass and helvolic acid production in submerged fermentation of Cordyceps taii

Advances in Production of Medicinal Mushrooms Biomass in Solid State and Submerged Bioreactors

Production of mushroom fruit bodies using farming technology could hardly meet the increasing demand of the world market. During the last several decades, there have been various basic and applied studies on fungal physiology, metabolism, process engineering, and (pre)clinical studies. The fundamental aspects of solid-state cultivation of various kinds of medicinal mushroom mycelia in various types of bioreactors were established. Solid-state cultivation of medicinal mushrooms for their biomass and bioactive metabolites production appear very suitable for veterinary use. Development of comprehensive submerged technologies using stirred tank and airlift bioreactors is the most promising technology for fast and large-scale production of medicinal fungi biomass and their pharmaceutically active products for human need. The potentials initiate the development of new drugs and some of the most attractive over-the-counter human and veterinary remedies. This article is to overview the engineering achievements in solid state and submerged cultivations of medicinal mushrooms in bioreactors.

Enhanced production of cordycepic acid from Cordyceps cicadae isolated from a wild environment

Cordyceps acid is an active component of Cordyceps cicadae and has a variety of medicinal uses, including anti-tumor effects, the prevention of cerebral hemorrhaging and myocardial infarction, and the inhibition of a wide range of bacteria. The objectives of this study were to identify C. cicadae fungi and optimize the culture conditions to obtain a high yield of cordycepic acid. First, a wild C. cicadae was identified by morphological observation and rDNA sequence analysis. Secondly, the optimal fermentation conditions were determined using a single-factor method, a Plackett-Burman design, and a Box-Behnken response surface. Finally, using the yield of fruit bodies and the content of cordyceps acid as indices, combined with a single-factor experiment and a response surface design, the best combination of conditions for cultivation was determined. The results showed that the best combination was as follows: sucrose 2%, tryptone 2%, KH2PO4 0.4%, MgSO4·7H2O 0.4%, an initial pH of the fermentation liquid of 7.0, 5% inoculum, fermentation for 4.5 d, a ratio of medium to liquid of 1:1.7, illumination intensity 150 Lux, illumination time 15 h per day, and 70% humidity. The content of cordycepic acid in the fruiting bodies developed in cultivation was 2.07-fold higher than that in the wild C. cicadae. This study provides a theoretical basis for the large-scale cultivation of C. cicadae with a high concentration of cordycepic acid.

Cordyceps spp.: A Review on Its Immune-Stimulatory and Other Biological Potentials

In recent decades, interest in the Cordyceps genus has amplified due to its immunostimulatory potential. Cordyceps species, its extracts, and bioactive constituents have been related with cytokine production such as interleukin (IL)-1β, IL-2, IL-6, IL-8, IL-10, IL-12, and tumor necrosis factor (TNF)-α, phagocytosis stimulation of immune cells, nitric oxide production by increasing inducible nitric oxide synthase activity, and stimulation of inflammatory response via mitogen-activated protein kinase pathway. Other pharmacological activities like antioxidant, anti-cancer, antihyperlipidemic, anti-diabetic, anti-fatigue, anti-aging, hypocholesterolemic, hypotensive, vasorelaxation, anti-depressant, aphrodisiac, and kidney protection, has been reported in pre-clinical studies. These biological activities are correlated with the bioactive compounds present in Cordyceps including nucleosides, sterols, flavonoids, cyclic peptides, phenolic, bioxanthracenes, polyketides, and alkaloids, being the cyclic peptides compounds the most studied. An organized review of the existing literature was executed by surveying several databanks like PubMed, Scopus, etc. using keywords like Cordyceps, cordycepin, immune system, immunostimulation, immunomodulatory, pharmacology, anti-cancer, anti-viral, clinical trials, ethnomedicine, pharmacology, phytochemical analysis, and different species names. This review collects and analyzes state-of-the-art about the properties of Cordyceps species along with ethnopharmacological properties, application in food, chemical compounds, extraction of bioactive compounds, and various pharmacological properties with a special focus on the stimulatory properties of immunity.

Optimization of Liquid Culture Condition of a Novel Fungus Hygrophoropsis sp. and Antioxidant Activity of Extracts

To evaluate pharmacological activities of a novel fungus Hygrophoropsis sp., the influence of aeration rate on the production of mycelial biomass, exopolysaccharides (EPS), and intrapolysaccharides (IPS) in the fungus Hygrophoropsis sp. was investigated. And the water extracts of cultured Hygrophoropsis sp. mycelia and the fermentation broth were analyzed for their antioxidation activity by using four different assay methods such as hydroxyl radical scavenging, superoxide radical scavenging, hydrogen peroxide scavenging, and reducing power. The Hygrophoropsis sp. was cultivated under various aeration rates in a 7 l bioreactor. The highest mycelial biomass (3.98 mg/mL) and IPS production (19.63 mg/g) were obtained at aeration rate 4.5 v.v.m. The results showed that Hygrophoropsis sp., in general, possesses a strong antioxidation activity in all assays tested. The deproteinized extracts had stronger antioxidation activity as compared to the un-deproteinized extracts by using superoxide radical scavenging, hydrogen peroxide scavenging, and reducing power. Besides, the un-deproteinized extracts had stronger antioxidation activity as compared to the deproteinized extracts by using hydroxyl radical scavenging. Thus, the polysaccharide extractions from the Hygrophoropsis sp. studied have antioxidant activities in vitro, which may be a good source of natural antioxidants or further investigation as potential natural antioxidants.

Enhanced exopolysaccharide production in submerged fermentation of Ganoderma lucidum by Tween 80 supplementation

Bioactive polysaccharides extracted from Ganoderma lucidum (G. lucidum) have been widely applied in food and medicine for their multiple functions. In this study, G. lucidum exopolysaccharide (EPS) production in submerged fermentation was stimulated by Tween 80. The addition of 0.25% Tween 80 on day 3 gave a maximum production of mycelial biomass and EPS, with an increase of 19.76 and 137.50%, respectively. Analysis of fermentation kinetics showed that glucose was consumed faster after adding Tween 80, while the expression of EPS biosynthesis-related genes and ATP generation were greatly improved. Moreover, Tween 80 resulted in the significant accumulation of reactive oxygen species and increased cell membrane and cell wall permeability. The EPS from Tween 80-containing medium had higher contents of carbohydrate and uronic acid, lower molecular weight, and higher antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals than those of EPS produced in the absence of Tween 80. This study provides further evidence to clarify the stimulatory effects of Tween 80 in fermentation and provides a guide for the production of bioactive G. lucidum EPS.

Glucose-lowering and hypolipidemic activities of polysaccharides from Cordyceps taii in streptozotocin-induced diabetic mice

Background

Hyperglycemia and dyslipidemia are classic features of patients with diabetes mellitus (DM). Cordyceps taii, a folk medicinal fungus native to southern China, possesses various pharmacological activities. This study aimed to assess the glucose-lowering and hypolipidemic effects of polysaccharides from C. taii (CTP) in streptozotocin (STZ)-induced diabetic mice.

Methods

Kunming mice were intraperitoneally injected with STZ at a dose of 100 mg/kg body weight. After induction of diabetes, diabetic mice were randomly divided into five groups: diabetic mellitus group (DM), metformin-treated group, low, medium, and high-dose CTP-treated group (CTP-L, CTP-M, and CTP-H). Normal mice served as the control group. After treatment for 28 days, body weight, fasting serum insulin (FSI), fasting blood glucose (FBG), homeostasis model assessment-insulin resistance (HOMA-IR), triglyceride (TG), total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), high-density lipoprotein-cholesterol (HDL-C), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and C-reactive protein (CRP) levels were measured. Histological analysis of pancreatic tissue and immune organ indices was also performed to evaluate the anti-diabetes effect of CTP. SPSS (version 21.0) software was used for statistical analysis, and statistical differences were considered significant at p < 0.05.

Results

Compared with the DM group, the body weight and FSI level of CTP-H group increased by 36.13 and 32.47%, whereas the FBG and HOMA-IR decreased by 56.79 and 42.78%, respectively (p < 0.05). Histopathological examination of the pancreas revealed that CTP improved and repaired the impaired islet β-cells in pancreatic tissue. Compared with the DM group, the levels of TC, TG, and LDL-C decreased by 13.84, 31.87, and 36.61%, whereas that of HDL-C increased by 28.60% in CTP-H (p < 0.05). Further study showed that the thymus index in CTP-H was elevated by approximately 54.96%, and the secretion of pro-inflammatory cytokines TNF-α, IL-6, and CRP was inhibited by approximately 19.97, 34.46, and 35.41%, respectively (p < 0.05).

Conclusion

The anti-diabetes effect of CTP is closely associated with immunoregulation and anti-inflammation, and CTP may be considered as a therapeutic drug or functional food for DM intervention.

Improved production of jiangxienone in submerged fermentation of Cordyceps jiangxiensis under nitrogen deficiency

Jiangxienone produced by Cordyceps jiangxiensis exhibits significant cytotoxicity and good selectivity against various human cancer cells, especially gastric cancer cells. In this work, the effect of nitrogen deficiency on the accumulation of jiangxienone and the transcription levels of jiangxienone biosynthesis genes was studied in submerged fermentation of C. jiangxiensis. Results showed that accumulation of jiangxienone was improved under nitrogen deficiency condition. A maximal jiangxienone content of 3.2 µg/g cell dry weight was reached at 5 mM glutamine, and it was about 8.9-fold higher than that obtained at 60 mM glutamine (control). The transcription levels of the biosynthetic pathway genes hmgr and sqs and the nitrogen regulatory gene areA were upregulated by 7-, 14-, and 28-fold, respectively, in culture with 5 mM glutamine compared to the control. It was hypothesized that the jiangxienone biosynthesis may involve the mevalonate pathway in C. jiangxiensis. Taken together, our study indicated that nitrogen deficiency is an efficient strategy for enhancing jiangxienone accumulation in submerged fermentation of C. jiangxiensis, which is useful for further understanding the regulation of jiangxienone biosynthesis.

Synergic regulation of redox potential and oxygen uptake to enhance production of coenzyme Q10 in Rhodobacter sphaeroides

The physiological role of Coenzyme Q₁₀ (CoQ₁₀) as an electron carrier suggests its association with redox potential. Overexpression of glyceraldehyde-3-phosphate dehydrogenase type I (gapA-1) in Rhodobacter sphaeroides elevated the NADH/NAD⁺ ratio and meanwhile enhanced the CoQ₁₀ content by 58%, but at the sacrifice of biomass. On the other hand, Vitreoscilla hemoglobin was heterologously expressed to enhance the oxygen uptake ability of the cells, leading to 127% improvement of biomass. Subsequent coexpression of gapA-1 and vgb resulted in a CoQ₁₀ titer of 83.24mg/L, representing 71% improvement as compared to the control strain RspMCS. When gapA-1 and vgb genes were co-expressed in a previously created strain RspMQd [1], 163.5mg/L of CoQ₁₀ was produced. Finally, 600mg/L of CoQ₁₀ production was achieved in fed-batch fermentation. These results demonstrated the synergic effect of redox potential regulation and oxygen uptake improvement on enhancing CoQ₁₀ production in R. sphaeroides.

Dissolved oxygen control strategy for improvement of TL1-1 production in submerged fermentation by Daldinia eschscholzii

BACKGROUND

2,3-Dihydro-5-hydroxy-2-methylchromen-4-one (TL1-1) is a phenolic compound with significant anti-fungal and anti-cancer activities produced by Daldinia eschscholzii (D. eschscholzii). However, studies have rarely been reported on the fermentation process of D. eschscholzii due to the urgent demand for its pharmaceutical researches and applications.

RESULTS

In this work, the optimal fermentation medium for improved TL1-1 yield was first obtained in a shake flask. As the fermentation process was scaling up, the marked effects of dissolved oxygen (DO) on cell growth and TL1-1 biosynthesis were observed and confirmed. Controlling a suitable DO level by the adjustment of agitation speed and aeration rate remarkably enhanced TL1-1 production in a lab-scale bioreactor. Moreover, the fermentation of D. eschscholzii was successfully applied in 500-L bioreactor, and TL1-1 production has achieved 873.63 mg/L, approximately 15.4-fold than its initial production (53.27 mg/L).

CONCLUSIONS

Dissolved oxygen control strategy for enhancing TL1-1 production was first proposed. Furthermore, control of the appropriate DO level has successfully performed for improving TL1-1 yield and scale-up of D. eschscholzii fermentation process.

Synergistic antitumor efficacy of antibacterial helvolic acid from Cordyceps taii and cyclophosphamide in a tumor mouse model

The antibacterial agent helvolic acid, which was isolated from the active antitumor fraction of Cordyceps taii, showed potent cytotoxicity against different human cancer cells. In the present study, the in vivo antitumor effect of helvolic acid was investigated in murine sarcoma S180 tumor-bearing mice. Doses of 10 and 20 mg/kg/day helvolic acid did not exert significant antitumor activity. Interestingly, co-administration of 10 mg/kg/day helvolic acid and 20 mg/kg/day cyclophosphamide (CTX) - a well-known chemotherapy drug - showed promising antitumor activity with a growth inhibitory rate of 70.90%, which was much higher than that of CTX alone (19.5%). Furthermore, the combination markedly prolonged the survival of tumor-bearing mice. In addition, helvolic acid enhanced the immune organ index. The protein expression levels of β-catenin, cyclin D1, and proliferating cell nuclear antigen were significantly suppressed in mice treated with 20 mg/kg/day helvolic acid and in those receiving combination therapy. Taken together, these results indicated that helvolic acid in combination with CTX showed potent in vivo synergistic antitumor efficacy, and its mechanism of action may involve the Wnt/ β-catenin signaling pathway.

Antitumor and antimetastatic activities of chloroform extract of medicinal mushroom Cordyceps taii in mouse models

BACKGROUND

Cordyceps taii, an entomogenous fungus native to south China, is a folk medicine with varieties of pharmacological activities including anticancer effect. To validate the ethnopharmacological claim against cancer, the antitumor and antimetastatic activities of chloroform extract of C. taii (CFCT) were investigated in vivo.

METHODS

The in vitro cytotoxic activities of CFCT against human lung cancer (A549) and gastric cancer (SGC-7901) cells were evaluated using the Sulforhodamine B (SRB) assay. In vivo anti tumor and antimetastatic activities, Kunming mice bearing sarcoma 180 and C57BL/6 mice bearing melanoma B16F10 were employed, respectively. The antitumor effects of CFCT were completely evaluated on the basis of the tumor weight, survival time, histologic analysis, and immune organ indices. The histopathological change, metastatic foci and malignant melanoma specific marker HMB45 in the lung tissue were detected for the evaluation of the antimetastatic activity of CFCT.

RESULTS

CFCT exhibited dose- and time-dependent cytotoxicities against A549 and SGC-7901 cells with the IC50 values of 30.2 and 65.7 μg/mL, respectively. Furthermore, CFCT at a dose of 50 or 100 mg/kg could significantly inhibit the tumor growth in vivo and prolonged the survival time in two different models as compared with the model group, especially when combined with the CTX at a low dose rate. And it also increased spleen index of Kunming mice and thymus index of C57BL/6 mice. Meanwhile, histologic analysis illustrated that CFCT alone or in combination with CTX could induce tumor tissue necrosis of both models. In addition, CFCT at a dose of 50 or 100 mg/kg inhibited the lung metastasis of melanoma B16F10 in tumor-bearing C57BL/6 mice. The antimetastatic effect was also observed when CFCT was used in combination with CTX. In comparison to any other groups, CFCT at a dose of 100 mg/kg could effectively enhance the GSH-Px activities of various tissues in tumor-bearing C57BL/6 mice.

CONCLUSIONS

These findings demonstrate that CFCT has potent in vivo antitumor and antimetastatic activities, and may be helpful to the development of anticancer chemopreventive agents from C. taii.