Characterization of a chitin-glucan complex from the fruiting body of Termitomyces albuminosus (Berk.) Heim

Unveiling the structural properties and induced resistance activity in rice of Chitin/Chitosan-Glucan Complex of Rhizoctonia solani AG1 IA inner cell wall

Phytopathogen cell wall polysaccharides have important physiological functions. In this study, we isolated and characterized the alkali-insoluble residue on the inner layers of the Rhizoctonia solani AG1 IA cell wall (RsCW-AIR). Through chemical composition and structural analysis, RsCW-AIR was mainly identified as a complex of chitin/chitosan and glucan (ChCsGC), with glucose and glucosamine were present in a molar ratio of 2.7:1.0. The predominant glycosidic bond linkage of glucan in ChCsGC was β-1,3-linked Glcp, both the α and β-polymorphic forms of chitin were presented in it by IR, XRD, and solid-state NMR, and the ChCsGC exhibited a degree of deacetylation measuring 67.08 %. RsCW-AIR pretreatment effectively reduced the incidence of rice sheath blight, and its induced resistance activity in rice was evaluated, such as inducing a reactive oxygen species (ROS) burst, leading to the accumulation of salicylic acid (SA) and the up-regulation of SA-related gene expression. The recognition of RsCW-AIR in rice is partially dependent on CERK1.

Hierarchical structure and chemical composition of complementary segments of the fruiting bodies of Fomes fomentarius fungi fine-tune the compressive properties

Humanity is often fascinated by structures and materials developed by Nature. While structural materials such as wood have been widely studied, the structural and mechanical properties of fungi are still largely unknown. One of the structurally interesting fungi is the polypore Fomes fomentarius. The present study deals with the investigation of the light but robust fruiting body of F. fomentarius. The four segments of the fruiting body (crust, trama, hymenium, and mycelial core) were examined. The comprehensive analysis included structural, chemical, and mechanical characterization with particular attention to cell wall composition, such as chitin/chitosan and glucan content, degree of deacetylation, and distribution of trace elements. The hymenium exhibited the best mechanical properties even though having the highest porosity. Our results suggest that this outstanding strength is due to the high proportion of skeletal hyphae and the highest chitin/chitosan content in the cell wall, next to its honeycomb structure. In addition, an increased calcium content was found in the hymenium and crust, and the presence of calcium oxalate crystals was confirmed by SEM-EDX. Interestingly, layers with different densities as well as layers of varying calcium and potassium depletion were found in the crust. Our results show the importance of considering the different structural and compositional characteristics of the segments when developing fungal-inspired materials and products. Moreover, the porous yet robust structure of hymenium is a promising blueprint for the development of advanced smart materials.

Ganoderma lucidum spores-derived particulate β-glucan treatment improves antitumor response by regulating myeloid-derived suppressor cells in triple-negative breast cancer

Granular β-1,3-glucan extracted from the wall of Ganoderma lucidum spores, named GPG, is a bioregulator. In this study, we investigated the structural, thermal, and other physical properties of GPG. We determined whether GPG ameliorated immunosuppression caused by Gemcitabine (GEM) chemotherapy. Triple-negative breast cancer mice with GPG combined with GEM treatment had reduced tumor burdens. In addition, GEM treatment alone altered the tumor microenvironment(TME), including a reduction in antitumor T cells and a rise in myeloid-derived suppressor cells (MDSC) and regulatory T cells (Tregs). However, combined GPG treatment reversed the tumor immunosuppressive microenvironment induced by GEM. GPG inhibited bone marrow (BM)-derived MDSC differentiation and reversed MDSC expansion induced by conditioned medium (CM) in GEM-treated E0771 cells through a Dectin-1 pathway. In addition, GPG downgraded PD-L1 and IDO1 expression on MDSC while boosting MHC-II, CD86, TNF-α, and IL-6 expression. In conclusion, this study demonstrated that GPG could alleviate the adverse effects induced by GEM chemotherapy by regulating TME.

High-Performance Engineered Composites Biofabrication Using Fungi

Various natural polymers offer sustainable alternatives to petroleum-based adhesives, enabling the creation of high-performance engineered materials. However, additional chemical modifications and complicated manufacturing procedures remain unavoidable. Here, a sustainable high-performance engineered composite that benefits from bonding strategies with multiple energy dissipation mechanisms dominated by chemical adhesion and mechanical interlocking is demonstrated via the fungal smart creative platform. Chemical adhesion is predominantly facilitated by the extracellular polymeric substrates and glycosylated proteins present in the fungal outer cell walls. The dynamic feature of non-covalent interactions represented by hydrogen bonding endows the composite with extensive unique properties including healing, recyclability, and scalable manufacturing. Mechanical interlocking involves multiple mycelial networks (elastic modulus of 2.8 GPa) binding substrates, and the fungal inner wall skeleton composed of chitin and β-glucan imparts product stability. The physicochemical properties of composite (modulus of elasticity of 1455.3 MPa, internal bond strength of 0.55 MPa, hardness of 82.8, and contact angle of 110.2°) are comparable or even superior to those of engineered lignocellulosic materials created using petroleum-based polymers or bioadhesives. High-performance composite biofabrication using fungi may inspire the creation of other sustainable engineered materials with the assistance of the extraordinary capabilities of living organisms.

Fabrication of chitin-glucan nanofibers: Insights into mushroom pretreatment and subsequent acidic deep eutectic solvent-based esterification

Mushrooms contain chitin-glucan complex (CGC), a natural copolymer of chitin and glucan, and nanofibrillation enhances its applicability. Here, a novel method was used to fabricate chitin-glucan nanofibers (CGNFs) from white button mushrooms. The first stage was to pretreat the raw mushroom using hot water and alkali to remove water-soluble glucans and alkali-soluble proteins, respectively, producing a CGC amenable to nanofibrillation. The second stage was nanofibrillation via esterification using acidic deep eutectic solvents (DESs) and subsequent ultrasonication. Five choline chloride-based DESs containing mono- or dicarboxylic acid were tested for the CGC esterification. DESs with strong dicarboxylic acids expedited nanofibrillation by homogeneously dispersing the solid CGC, swelling CGC fibrils, and facilitating acidity-dependent esterification leading to steric and electrostatic repulsions. One CGNF, namely CGNF_CCMnA, was characterized: it contained chitin and glucan at an approximate ratio of 8:2 and exhibited desirable properties as nanomaterials, including small diameter (11 nm) and high colloidal (zeta potential < -30 mV above pH 5.8) and thermal stability (Tm, 315 °C). CGNF_CCMnA was tested for the adsorption to methylene blue, revealing a maximum adsorption capacity of 82.58 mg/g. The proposed approach is an efficient and readily applicable method to fabricate various mushroom-derived safe CGNFs and to produce related nanomaterials.

Extraction, quantification, characterization, and application in food packaging of chitin and chitosan from mushroom: A review

The application of chitin in food systems is limited by its insolubility in some common solvents and poor degradability. Hence, it is deacetylated to obtain chitosan, an industrially important derivative with excellent biological properties. Fungal-sourced chitosan is gaining prominence and industrial attraction because of its superior functional and biological properties, and vegan appeal. Further, the absence of such compounds as tropomyosin, myosin light chain, and arginine kinase, which are known to trigger allergic reactions, gives it an edge over marine-sourced chitosan in food and pharmaceutical applications. Mushrooms are macro-fungi with a significant content of chitin, with many authors reporting the highest content to be in the mushroom stalks. This indicates a great potential for the valorisation of a hitherto waste product. Hence, this review was written to provide a global summary of literature reports on the extraction and yield of chitin and chitosan from different fruiting parts of some species of mushroom, different methods used to quantify extracted chitin, as well as physicochemical properties of chitin and chitosan from some mushroom species are presented. Critical comparisons of reports on chitin and chitosan from mushrooms and other sources are made. This report concludes with an exposition of the potential application of mushroom-sourced chitosan for food packaging application. The reports from this review provide a very positive outlook regarding the use of mushrooms as a sustainable source of chitin and chitosan and the subsequent application of chitosan as a functional component in food packaging.

An optimization of fungal chitin grafted polyaniline for ammonia gas detection via Box Behnken design

In this work, chitin (Ch) was chemically extracted from wild mushrooms and then grafted to polyaniline (PANI) to form a composite (Ch-g-PANI) to detect ammonia (NH₃) gas. The Ch-g-PANI was comprehensively characterized using Scanning electron microscopy (SEM), elemental mapping, thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) and UV-Vis spectroscopy. The NH₃ gas detection optimization was evaluated using Box-Behnken Design. Typically, physical factors such as (A)film layer, (B)loading %, and (C)contact time were investigated and validated through the analysis of variance (ANOVA). The ANOVA revealed that dual interactions between (A)film layer - (C)contact time, and (B)loading % - (C)contact time are among the significant factors. By considering these significant interactions, the highest sensitivity was obtained when (A)film layer (3), (B)loading (5 %), and (C)contact time (10 min) in NH₃ gas detection. Then, the optimized Ch-g-PANI was tested in the linear range of NH₃ gas concentration from 10 to 50 ppm, which resulted in a linear calibration curve with R² = 0.994 and a detection limit of 15.03 ppm. Sensor performances showed that Ch-g-PANI films possess high selectivity for NH₃ gas among the common interfering gases and the film can be reused for up to 6 cycles. Therefore, the new mushroom-sourced Ch-g-PANI is an inexpensive and economical sensor in the NH₃ gas sensor field.

Development of curcumin incorporated composite films based on chitin and glucan complexes extracted from Agaricus bisporus for active packaging of chicken breast meat

Composite films were prepared by combining different concentrations of curcumin with chitin and glucan complexes (CGCs) extracted from Agaricus bisporus via a solution casting method. The developed curcumin doped CGC (CGC/Cu) films were characterized in terms of surface, optical, structural, barrier, mechanical, antioxidant, and antimicrobial properties. The biodegradability of CGC/Cu films was determined in soil for 14 days. The incorporation of curcumin significantly affected the surface morphology and improved light barrier properties, radical scavenging activity, and total phenolic content of the films. The CGC/Cu films containing different concentrations of curcumin showed antibacterial activity against Escherichia coli, while antibacterial activity against Staphylococcus aureus was not observed with the developed films. Afterward, the microbial properties of the fresh chicken breast were examined during refrigerated storage for 10 days. The shelf-life of chicken samples wrapped in the developed film was extended at least 40 % compared to the control sample. In conclusion, curcumin incorporated CGC based films can serve as a promising biodegradable active packaging material to improve the shelf-life of meat products.

Structure and Properties of Cellulose/Mycelium Biocomposites

The current environmental problems require the use of low-energy, environmentally friendly methods and nature-like technologies for the creation of materials. In this work, we aim to study the possibility of the direct biotransformation of fibrillar cellulose by fungi through obtaining a cellulose/mycelium-based biocomposite. The cellulose micro- and nanofibrils were used as the main carbon sources in the solid-phase cultivation of basidiomycete Trametes hirsuta. The cellulose fibrils in this process act as a template for growing mycelium with the formation of well-developed net structure. The biotransformation dynamics of cellulose fibrils were studied with the help of scanning electron microscopy. The appearance of nitrogen in the structure of formed fibers was revealed by elemental analysis and FTIR-spectroscopy. The fibers diameters were estimated based on micrograph analysis and the laser diffraction method. It was shown that the diameter of cellulose fibrils can be tuned by fungi through obtaining cellulose-based mycelium fibers with a narrower diameter-size distribution as compared to the pristine cellulose fibrils. The morphology of the resulting mycelium differed when the micro or nanofibrils were used as a substrate.

Physicochemical characterization, adsorption function and prebiotic effect of chitin-glucan complex from mushroom Coprinus comatus

Chitin-glucan complex (CGC) is a novel insoluble dietary fiber with multiple physiological activities. In this work, CGC was extracted from the fruiting body of Coprinus comatus and its physicochemical properties and prebiotic effects were investigated. The results indicated that CGC consisted of glucosamine and glucose in a molar ratio of 67: 33 with degree of acetylation of 61.91% and crystallinity index of 25.40%. The maximum degradation temperature was determined to be 307.52 °C, and a woven fibrous structure was observed by scanning electron microscopy. CGC exhibited higher oil-holding capacity, water-holding capacity and nitrite ion adsorption capacity than commercial chitin, and showed potential prebiotic effects. Compared with control and commercial chitin, CGC significantly (P < 0.05) increased the concentration of propionic and butyric acids. These results suggested that CGC from C. comatus was promising to be an alternative source of CGC products and used as a bioactive ingredient in functional foods.

Influence of Dissolved Oxygen Level on Chitin–Glucan Complex and Mannans Production by the Yeast Pichia pastoris

The yeast Pichia pastoris was cultivated under different dissolved oxygen (DO) levels (5, 15, 30 and 50% of the air saturation) to evaluate its impact on the production of the cell-wall polysaccharide chitin–glucan complex (CGC) and mannans. Decreasing the DO level from 50 to 15% had no significant impact on cell growth but substrate conversion into biomass was improved. Under such conditions, a mannans content in the biomass of 22 wt% was reached, while the CGC content in the biomass was improved from 15 to 18 wt%, confirming that the DO level also impacted on P. pastoris cell-wall composition. Overall mannans and CGC volumetric productivity values of 10.69 and 8.67 g/(L. day) were reached, respectively. On the other hand, the polymers’ composition was not significantly affected by decreasing the DO level. These results demonstrated that considerable energy savings can be made in the polysaccharide production process by reducing the DO level during cultivation of P. pastoris by improving the overall polymers’ productivity without altering their composition. This has impact on the polysaccharide production costs, which is of considerable relevance for process scale-up and products’ commercialization.

Isolation, Structural Properties, and Bioactivities of Polysaccharides from Mushrooms Termitomyces: A Review

Termitomyces are well-known wild edible and medicinal basidiomycete mushrooms. The frequent consumption of Termitomyces stimulated studies on their health-promoting properties. Numerous health benefits of Termitomyces are associated with the main categories of components in Termitomyces, polysaccharides. Although the homopolysaccharides β-glucans are believed to be the major bioactive polysaccharides of Termitomyces, other heteropolysaccharides also possess biological activities. In this review, the extraction methods, chemical structures, and biological activities of polysaccharides from Termitomyces were thoroughly reviewed. The polysaccharides from different species of Termitomyces differ in molecular weight, monosaccharide composition, and linkages of constituent sugars. The health-promoting effects, including antioxidation, ulcer-healing and analgesic properties, immunomodulation, hypolipidemic and hepatoprotective effects, and antidiabetic properties of Termitomyces polysaccharides were summarized and discussed. Further studies were needed for a better understanding of the relationship between the fine chemical structure and health-promoting properties. This review provides a theoretical overview for future studies and utilization of Termitomyces polysaccharides.

The sustainability of industrial insect mass rearing for food and feed production: zero waste goals through by-product utilization

Insect production provides an opportunity to solve problems in our food system. Producers are focused on redirecting waste streams to strive for a zero waste system. By-products and left-over substrates generated include: frass, chitin, and lipids. Frass can be beneficial as a plant fertilizer. It is also known to exhibit anti-microbial and anti-pathogenic properties that may be utilized as a potential insecticide. Chitin has similar fertilizer and anti-pathogen properties. Chitin also produces anti-inflammatory and antimicrobial properties, potentially improving immune responses in animals. Fatty acids found in lipids may serve as environmentally friendly biodiesel. Additionally, the oleic acids found in lipids have known health benefits for humans and other animals. As insect systems expand, zero waste goals will increase in importance.

Characterization of chitin-glucan complex from Tremella fuciformis fermentation residue and evaluation of its antibacterial performance

Submerged fermentation of fungi is an efficient way to obtain extracellular polysaccharides, however, in this process, excess discarded biomass is produced. In this study, Tremella fuciformis mycelia were reused as the raw material to isolate a novel fungal chitin-glucan complex (CGC-TFM) using alkaline extraction. Characteristic analysis revealed that the CGC-TFM consisted of glucosamine/acetylglucosamine and glucose (GlcN:Glc = 26:74 mol%), indicating a reference to the β polymorphism of chitin-glucan complex, with the molecular weight and crystallinity index of 256 ± 3.0 kDa and 54.25 ± 1.04%, respectively. Fourier transform infrared spectroscopy, X-ray diffraction, nuclear magnetic resonance, and scanning electron microscopy analyses confirmed that the chitin portion of the CGC-TFM exhibited a typical β configuration and N-acetylation degree of 70.52 ± 2.09%. Furthermore, the CGC-TFM exhibited good thermal stability and effective Escherichia coli inhibition ability, indicating that it could be applied as a potential food packaging material.

Preparation and characterization of various chitin-glucan complexes derived from white button mushroom using a deep eutectic solvent-based ecofriendly method

Deep eutectic solvents (DESs) have gained great interests as ecofriendly and safe solvents in diverse areas. Herein, various chitin-glucan complexes (CGCs) were prepared from white button mushroom (Agaricus bisporus) using DESs. Ultrasonication of mushroom in five DESs yielded two types of CGCs from each DES, one from the DES-insoluble residue (DES_P) and another from the DES-soluble extract (DES_S). The ten resulting CGCs with varying chitin-to-β-glucan ratios were compared with alkali-insoluble matter (AIM), chemically prepared using NaOH. BU_S and BU_P, prepared using BU comprising betaine and urea, were obtained in the highest yields with reasonably low protein and mineral contents. Despite different acetylation degrees (77.3% and 57.3%, respectively), BU_S and BU_P both degraded at 318 °C and showed remarkably low crystallinity (32.0% and 37.0% for BU_S and BU_P, respectively) compared to AIM, commercial chitin, and the reported CGCs. The surface of BU_S and BU_P was very porous and rough compared with AIM as a result of reduced H-bonds and lowered crystallinity. The DES-based method can potentially enable the preparation of advanced biomaterials from mushrooms under mild and ecofriendly conditions.

Obtaining chitin, chitosan and their melanin complexes from insects

Interest in insects as a source of valuable biologically active substances has significantly increased over the past few years. Insects serve as an alternative source of chitin, which forms up to 40% of their exoskeleton. Chitosan, a deacetylated derivative of chitin, attracts the attention of scientists due to its unique properties (sorption, antimicrobial, film-forming, wound healing). Furthermore, some insect species are unique and can be used to obtain chitin- and chitosan-melanin complexes in the later stages of ontogenesis. Due to the synergistic effect, chitosan and melanin can enhance each other's biological activity, providing a wide range of potential applications.

Bioactive Phytochemical Constituents of Wild Edible Mushrooms from Southeast Asia

Mushrooms have a long history of uses for their medicinal and nutritional properties. They have been consumed by people for thousands of years. Edible mushrooms are collected in the wild or cultivated worldwide. Recently, mushroom extracts and their secondary metabolites have acquired considerable attention due to their biological effects, which include antioxidant, antimicrobial, anti-cancer, anti-inflammatory, anti-obesity, and immunomodulatory activities. Thus, in addition to phytochemists, nutritionists and consumers are now deeply interested in the phytochemical constituents of mushrooms, which provide beneficial effects to humans in terms of health promotion and reduction of disease-related risks. In recent years, scientific reports on the nutritional, phytochemical and pharmacological properties of mushroom have been overwhelming. However, the bioactive compounds and biological properties of wild edible mushrooms growing in Southeast Asian countries have been rarely described. In this review, the bioactive compounds isolated from 25 selected wild edible mushrooms growing in Southeast Asia have been reviewed, together with their biological activities. Phytoconstituents with antioxidant and antimicrobial activities have been highlighted. Several evidences indicate that mushrooms are good sources for natural antioxidants and antimicrobial agents.

Green synthesis, characterization and biological evaluation of chitin glucan based zinc oxide nanoparticles and its curcumin conjugation

A well-organized, simplistic, and green route of chitin-glucan based zinc oxide nanoparticles (ChGC@ZnONPs) was synthesized using reducing and capping agent both in one as chitin-glucan complex (ChGC). Herein we report the bio-synthesis of Cur-ChGC@ZnONPs by the conjugation of curcumin (Cur) with ChGC@ZnONPs for the improvement of antioxidant and antibacterial activity. The synthesized nanoparticles were characterized by the UV-Visible (UV-Vis), particle size analyser, scanning electron microscope (SEM) with Energy-dispersive X-ray spectroscopy (EDX), Transmission electron microscope (TEM), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). Structure analysis, shape and crystalline size of nanomaterials were confirmed by scanning electron microscopy (SEM) and Transmission Electron Microscopy (TEM). The particle size analyser showed the particle size of nanomaterials and stability. Crystalline nature of both ChGC@ZnONPs and Cur-ChGC@ZnONPs were confirmed by the XRD spectra and FT-IR spectrum was used to examine the functional groups of nanomaterials. The antioxidant potential of conjugated nanomaterials were estimated using a DPPH free radical scavenging assay and ABTS^+⁎ assay. This analysis showed that after loading of Cur, antioxidant activity increases. The antibacterial assessment of conjugated nanomaterials were tested by different microorganisms and showed excellent antibacterial activity.