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

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.

Production of Lipopeptides from Bacillus velezensis BVQ121 and Their Application in Chitosan Antibacterial Coating

The extracellular substance of Bacillus has antibacterial effects inhibiting multiple foodborne pathogens and plays important roles in food production. This study found one Bacillus velezensis BVQ121 strain producing antibacterial lipopeptides (BVAL). After optimization of the fermentation conditions, the BVAL yield was the highest at 1.316 ± 0.03 g/L in reality with the initial pH 6.0, temperature 31 °C, and shaker speed 238 rpm when the optimal nitrogen and carbon sources were used in Landy medium for fermentation. The antibacterial components were identified as iturin, surfactin, and fengycin by HPLC and MALDI-TOF-MS. The MIC was at 2 mg/mL and MBC was at 5 mg/mL. The 6% weight ratio of nanocellulose dosage in chitosan solution could improve the tensile length and strength of the film, and the antibacterial performance was enhanced by the addition of BVAL. The addition of BVAL had no effect on the color and ductility of the film and improved its antibacterial effect. The shelf life of pigeon eggs can be extended by more than 10 days to resist bacterial infections after coating with the chitosan-nanocellulose-BVAL film solution.

The function and application of edible fungal polysaccharides

Edible fungi, commonly known as mushrooms, are precious medicinal and edible homologous gifts from nature to us. Edible fungal polysaccharides (EFPs) are a variety of bioactive macromolecular which isolated from fruiting bodies, mycelia or fermentation broths of edible or medicinal fungus. Increasing researches have confirmed that EFPs possess multiple biological activities both in vitro and in vivo settings, including antioxidant, antiviral, anti-inflammatory, immunomodulatory, anti-tumor, hypoglycemic, hypolipidemic, and regulating intestinal flora activities. As a result, they have emerged as a prominent focus in the healthcare, pharmaceutical, and cosmetic industries. Fungal EFPs have safe, non-toxic, biodegradable, and biocompatible properties with low immunogenicity, bioadhesion ability, and antibacterial activities, presenting diverse potential applications in the food industries, cosmetic, biomedical, packaging, and new materials. Moreover, varying raw materials, extraction, purification, chemical modification methods, and culture conditions can result in variances in the structure and biological activities of EFPs. The purpose of this review is to provide comprehensively and systematically organized information on the structure, modification, biological activities, and potential applications of EFPs to support their therapeutic effects and health functions. This review provides new insights and a theoretical basis for prospective investigations and advancements in EFPs in fields such as medicine, food, and new materials.

King crab gills as a new source of chitin/chitosan and protein hydrolysates

This is the first report on the physicochemical properties of chitin obtained from gills of the king crab Paralithodes camtschaticus. In the present study, we investigated the chemical composition of red king crab gills and considered methods of its complex processing to obtain chitin and enzymatic protein hydrolysates. The gills contained approximately 21 % chitin in terms of dry matter. For the first time, the gills of the king crab were investigated as a source of chitin and chitosan. Chitin was isolated from crab gills using chemical and enzymatic methods. The physicochemical properties of chitin and chitosan from the gills were investigated. By performing infrared spectroscopy and X-ray phase analyses, the chitin present in the gills was established to be α-chitin. The physical and chemical properties (degree of deacetylation, molecular weight and crystal structure) of gill chitin and chitosan were absolutely similar to those of crab shell. Crab gills can be used as an additional source of chitin in the integrated processing of king crabs. The yield of chitin from the gills is up to 45 % of the yield of chitin from the crab carapace.

Synergistic performance of collagen-g-chitosan-glucan fiber biohybrid scaffold with tunable properties

Hybrid biocomposite scaffolds (HBS) that serve as a carrier for cell proliferation and differentiation are increasingly used for tissue regeneration. 3D hybrid scaffold based on collagen-grafted-chitosan-glucan fiber (CO-g-CGF-HBS) was prepared by freeze-drying technique. The swelling percentage, hydrolytic stability, and modulus of elasticity of HBS were enhanced after the chemical modification of CO with CGF. Pore size and porosity of HBS were decreased with an increased CGF ratio. HBS exhibits a higher reduction rate against different types of bacteria compared with a control sample. Thus, chemical modification of CO with different ratios of CGF significantly improved the physicochemical, antibacterial properties of HBS.

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.