Enhanced exopolysaccharide production by Cordyceps militaris using repeated batch cultivation

Optimization of cultural and nutritional conditions to enhance mycelial biomass of Cordyceps militaris using statistical approach

Cordyceps militaris is a fungus with numerous therapeutic properties that has gained worldwide popularity due to its potential health benefits. The fruiting body of this mushroom is highly expensive and takes a longer time to produce, making mycelial a sustainable and cost-effective alternative. The study investigates and optimizes cultural and nutritional conditions to maximize mycelial biomass. The initial optimization was done by the conventional single-factor approach, followed by Plackett-Burman design to screen the most significant variables, with yeast extract, temperature, and glucose being the most significant, contributing 11.58%, 49.74%, and 27.98%, respectively, in mycelial biomass production. These variables were then optimized using response surface methodology (RSM) based on central composite design (CCD). The study observed that temperature and glucose had the highest impact on mycelial biomass, with p-values of 0.0128 and 0.0191, respectively. Under the optimized conditions, temperature 20 °C, glucose 2.5% (w/v), and yeast extract 0.8% (w/v), the maximal yield of mycelial biomass reached 547 ± 2.09 mg/100 mL, which was 1.95-fold higher than the yield in the basal medium. These findings suggest that optimizing the cultural and nutritional conditions can enhance mycelial biomass production of Cordyceps militaris, offering a sustainable and cost-effective source of this valuable fungus.

A review on polysaccharide biosynthesis in Cordyceps militaris

Cordyceps militaris (C. militaris) is an edible parasitic fungus with medicinal properties. Its bioactive polysaccharides are structurally diverse and exhibit various metabolic and biological activities, including antitumor, hypoglycemic, antioxidant, hypolipidemic, anti-inflammatory, immunostimulatory, and anti-atherosclerotic effects. These properties make C. militaris-derived polysaccharides a promising candidate for future development. Recent advancements in microbial fermentation technology have enabled successful laboratory cultivation and extraction of these polysaccharides. These polysaccharides are structurally diverse and exhibit various biological activities, such as immunostimulatory, antioxidant, antitumor, hypolipidemic, and anti-atherosclerotic effects. This review aims to summarize the structure and production mechanisms of polysaccharides from C. militaris, covering extraction methods, key genes and pathways involved in biosynthesis, and fermentation factors that influence yield and activity. Furthermore, the future potential and challenges of utilizing polysaccharides in the development of health foods and pharmaceuticals are addressed. This review serves as a valuable reference in the fields of food and medicine, and provides a theoretical foundation for the study of polysaccharides.

An insight into the nutritional and medicinal value of edible mushrooms: A natural treasury for human health

Edible mushrooms have been cherished worldwide because of their nutraceutical and medicinal properties. They are recognized as the new superfood for the future due to their low-calorie content, high-protein content, low lipid levels, low cholesterol levels, and abundance of essential vitamins. The fruiting body of edible mushrooms contains a plethora of primary and secondary metabolites. However, submerged cultivation is a more reliable and controlled way of production of mycelium biomass and many bioactive compounds. Several bioactive metabolites present in mushrooms possess a range of beneficial properties, including antioxidant, antimicrobial, anticancer, antidiabetic, anti-inflammatory, antiviral and anti-COVID-19 activities. Consumers have turned more intrigued in mushroom-containing products as the world needs to diversify its protein sources to meet the growing demand for protein. In this context, mushrooms are viewed as a promising source of bioactive chemicals that can be employed as an alternative to meat products. This review aims to summarise the most recent data regarding the beneficial health effects and the development of mushroom-based food products.

Enhanced exopolysaccharide production of Cordyceps militaris via mycelial cell immobilization on plastic composite support in repeated-batch fermentation

Repeated-batch fermentation with fungal mycelia immobilized in plastic composite support (PCS) eliminates the lag phase during fermentation and improves metabolite productivity. The strategy is implemented herein, and a novel modified PCS is developed to enhance exopolysaccharide (EPS) production from the medicinal fungus Cordyceps militaris. A modified PCS (SYE + PCS) was made by compositing polypropylene (PP) with a nutrient mixture containing soybean hull, peptone, yeast extract, and minerals (SYE+). The use of SYE + PCS has consistent cell productivity throughout the multiple fermentation cycles, which resulted in a more higher cell productivity after second batch compared to unmodified PCS. The cell grown on SYE + PCS also generates a higher yield of EPS (3.36, 6.93, and 5.72 g/L in the first, second, and third fermentation cycles, respectively) up to three-fold higher than the cell immobilized on unmodified PCS. It is also worth noting that the EPS from mycelium grown on SYE + PCS contains up to 2.3-fold higher cordycepin than those on unmodified PCS. The presence of nutrients in SYE + PCS also affects the hydrophobicity and surface roughness of the PC, improving mycelial cell adhesion. This study also provides a preliminary antioxidant activity assessment of EPS from immobilized C. militaris grown with SYE + PCS.

Advances in Polysaccharide Production Based on the Co-Culture of Microbes

Microbial polysaccharides are natural carbohydrates that can confer adhesion capacity to cells and protect them from harsh environments. Due to their various physiological activities, these macromolecules are widely used in food, medicine, environmental, cosmetic, and textile applications. Microbial co-culture is an important strategy that is used to increase the production of microbial polysaccharides or produce new polysaccharides (structural alterations). This is achieved by exploiting the symbiotic/antagonistic/chemo-sensitive interactions between microbes and stimulating the expression of relevant silent genes. In this article, we review the performance of polysaccharides produced using microbial co-culture in terms of yield, antioxidant activity, and antibacterial, antitumor, and anti-inflammatory properties, in addition to the advantages and application prospects of co-culture. Moreover, the potential for microbial polysaccharides to be used in various applications is discussed.

Direct Utilization and Conversion of raw Starch to Exopolysaccharides by a newly isolated Amylolytic Streptococcus sp

A newly isolated culture is identified as Streptococcus lutetiensis with significant starch saccharifying activity. Along with considerable amylolytic property (~ 2.71U/mL), the culture exhibited significant production of exopolysaccharide (EPS) in starch medium. Interestingly, the glycosyl transferase activity which is essential in the biosynthesis of polysaccharide is also detected in the culture and after screening and process optimization, a maximum EPS titre of 19.92 ± 0.5g/L was obtained from cassava starch. The crude EPS, after purification and characterization (monosaccharide analysis, FT-IR, TGA, GPC, NMR, and SEM) was found to be of dextran nature with a Mw of 1275.36kDa. Dextran type exopolysaccharide are synthesized by dextransucrase enzyme by the transfer of glucosyl residues from sucrose to dextran polymer. Iinterestingly, the glycosyl transferase enzyme activity which is essential in the biosynthesis of EPS is also detected in the culture. The particle size (447.8 dnm) and the zeta potential (-33.4) analysis of the purified EPS showed that the EPS produced is a stable molecule and has a random coil confirmation when exposed to alkaline condition with shear thinning property. One step conversion of sustainable low-cost starchy raw materials without adding external enzymes for hydrolysis, improved the economic viability of EPS production.

Optimisation of the production of a selenium-enriched polysaccharide from Cordyceps cicadae S1 and its structure and antioxidant activity

The fermentation medium of a newly identified Cordyceps cicadae S1 was optimized by response surface methodology, with the optimal medium containing sucrose (80 g/L), yeast powder (60 g/L), KH₂PO₄ (5 g/L), MgSO₄·7H₂O (1 g/L) and Na₂SeO₃ (0. 1 g/L). Under these conditions, the extracellular polysaccharide yield was 8.09 g/L. A novel selenium-enriched polysaccharide (PACI-1) was isolated from Cordyceps cicadae, purified and identified as a homofructose polysaccharide with a low average molecular weight of 9.95 × 10³ Da. The fine structure of PACI-1 was analyzed using NMR, CD, and AFM. Additionally, the in vitro antioxidant results showed that the PACI-1 had stronger antioxidant capacity than natural polysaccharides. These results provided a candidate strain for producing selenium polysaccharide and a new polysaccharide from C. cicadae, which showed good antioxidant activity.

Structural Elucidation and Activities of Cordyceps militaris-Derived Polysaccharides: A Review

Cordyceps militaris is a parasitic edible fungus and has been used as tonics for centuries. Polysaccharides are a major water-soluble component of C. militaris. Recently, C. militaris-derived polysaccharides have been given much attention due to their various actions including antioxidant, anti-inflammatory, anti-tumor, anti-hyperlipidemic, anti-diabetic, anti-atherosclerotic, and immunomodulatory effects. These bioactivities are determined by the various structural characteristics of polysaccharides including monosaccharide composition, molecular weight, and glycosidic linkage. The widespread use of advanced analytical analysis tools has greatly improved the elucidation of the structural characteristics of C. militaris-derived polysaccharides. However, the methods for polysaccharide structural characterization and the latest findings related to C. militaris-derived polysaccharides, especially the potential structure-activity relationship, have not been well-summarized in recent reviews of the literature. This review will discuss the methods used in the elucidation of the structure of polysaccharides and structural characteristics as well as the signaling pathways modulated by C. militaris-derived polysaccharides. This article provides information useful for the development of C. militaris-derived polysaccharides as well as for investigating other medicinal polysaccharides.

Biomass and Cordycepin Production by the Medicinal Mushroom Cordyceps militaris-A Review of Various Aspects and Recent Trends towards the Exploitation of a Valuable Fungus

Cordyceps militaris is an entomopathogenic ascomycete with similar pharmacological importance to that of the wild caterpillar fungus Ophiocordyceps sinensis. C. militaris has attracted significant research and commercial interest due to its content in bioactive compounds beneficial to human health and the relative ease of cultivation under laboratory conditions. However, room for improvement exists in the commercial-scale cultivation of C. militaris and concerns issues principally related to appropriate strain selection, genetic degeneration of cultures, and substrate optimization. In particular, culture degeneration-usually expressed by abnormal fruit body formation and reduced sporulation-results in important economic losses and is holding back investors and potential growers (mainly in Western countries) from further developing this highly promising sector. In the present review, the main factors that influence the generation of biomass and metabolites (with emphasis on cordycepin biosynthesis) by C. militaris are presented and evaluated in conjunction with the use of a wide range of supplements or additives towards the enhancement of fungal productivity in large-scale cultivation processes. Moreover, physiological and genetic factors that increase or reduce the manifestation of strain degeneration in C. militaris are outlined. Finally, methodologies for developing protocols to be used in C. militaris functional biology studies are discussed.

The Feasibility of Utilizing Cultured Cordyceps militaris Residues in Cosmetics: Biological Activity Assessment of Their Crude Extracts

Solid-based residues (SBRs) left from harvesting the fruiting bodies of cultured Cordyceps mushrooms are a challenge to sustainability. Therefore, in this study, the SBRs from the cultivation of Cordyceps militaris (C. militaris) via solid-state fermentation (SSF) were employed to prepare crude extracts, with the aim of considering their possible use in cosmetics. The SBRs obtained from cultivation with solid media containing defatted rice bran mixed with barley, white rice, Riceberry rice, and wheat were named SBR-B, SBR-R, SBR-Rb, and SRB-W, respectively. They were extracted with solvents of differing polarity and then evaluated for their total phenolic content (TPC), total flavonoid content (TFC), and total carbohydrate content (TCC). In addition, antioxidant and tyrosinase inhibitory activities, photoprotection, and cytotoxicity were also assessed. The results revealed that the total bioactive contents and biological capacities of crude SBR extracts were significantly influenced by the types of SBR and extraction solvent (p < 0.05). The SBR-B extracted with hot water exhibited the highest antioxidant activity (66.62 ± 2.10, 212.00 ± 3.43, and 101.62 ± 4.42 mg TEAC/g extract) when assayed by DPPH, ABTS, and FRAP methods, respectively, whereas tyrosinase inhibitory activity (51.13 ± 1.11 mg KAE/g extract) with 90.43 ± 1.96% inhibition at 1 mg/mL was excellently achieved by SBR-Rb extracted by 50% (v/v) ethanol. Correlations between bioactive contents in the crude extracts and their biological activities were mostly proven at a strong level (p < 0.01). The capability of the crude extracts to absorb UV over the range of 290–330 nm disclosed their potential roles as natural UV absorbers and boosters. Cytotoxicity analysis using fibroblast cell lines tested with hot water and 50% (v/v) ethanolic SBR extracts demonstrated safe use within a concentration range of 0.001–10 mg/mL. Interestingly, their fibroblast proliferative capacity, indicating anti-aging properties, was highly promoted. The chemical composition analyzed via LC–MS/MS techniques showed that seven phenolic acids and four flavonoids were identified in the crude SBR extracts. Furthermore, the other compounds present included nucleosides, nucleobases, amino acids, sugars, phospholipids, alkaloids, organic acids, vitamins, and peptides. Therefore, it is emphasized that SBRs from C. militaris can be a prospective source for preparing crude extracts employed in cosmetics. Lastly, they could be further utilized as multifunctional ingredients in cosmetics and cosmeceuticals.

Extracellular polysaccharide biosynthesis in Cordyceps

Cordyceps is a parasitic edible fungus with a variety of metabolically active ingredients. The main active ingredient, extracellular polysaccharide (EPS), shows favourable application prospects in prevention and treatment of certain diseases. EPS extracted from different parts of various Cordyceps species can be used in health foods or medicinal preparations because of the structural diversity and multiple bioactivities. In terms of the complexity of composition and structure, researchers have speculated on the anabolic pathways of EPSs and the genes involved in the synthesis process. Studies to increase the yield of polysaccharides are limited because the synthesis pathways and anabolic regulation mechanisms of Cordyceps exopolysaccharide remain unknown. This review summarises the current researches in the yield of Cordyceps polysaccharides. A mechanism for the biosynthesis of Cordyceps polysaccharides was proposed by referring to the polysaccharide synthesis in other species. Furthermore, we also discuss the future perspective and ongoing challenges of EPS in uses of health foods and pharmaceutics.

Oil crop wastes as substrate candidates for enhancing erythritol production by modified Yarrowia lipolytica via one-step solid state fermentation

Oil crop wastes are attractive feedstocks in microbial processes due to their low cost. However, the product yields can be limited by their undesirable nitrogen surplus. Present study proposed a one-step solid state fermentation (SSF) method for producing erythritol from unrefined oil crop wastes using a modified strain Y. lipolytica M53-S. Enhanced erythritol production (185.4 mg/gds) was obtained from peanut press cake mixed with 40% sesame meal and 10% waste cooking oil. The process was performed at pH 4.0 in 5 L flasks, with initial moisture content, NaCl addition, and inoculum size of 70%, 0.02 g/gds, and 7.5 × 10⁴ cells/gds, respectively. This procedure showed advantages in terms of lower material cost than that of submerged fermentation and shorter culture cycle (96 h) than other SSF processes. In repeated-batch fermentation, erythritol was continuously produced for seven cycles. This study presents a feasible approach in developing an efficient erythritol cultivation from nitrogen-rich wastes.