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In this study, novel blends of mycelium biocomposites (MB) were developed. Various combinations of birch sawdust and hemp shives with birch bark (BB) and wheat bran (WB) additives were inoculated with basidiomycete Trametes versicolor to produce self-growing biomaterials. MB were characterized according to mycelial biomass increment in final samples, changes in chemical composition, elemental (C, H, N) analyses, granulometry of substrates, water-related and mechanical properties, as well as mold resistance and biodegradability. The mycelial biomass in manufactured MB increased by ~100% and ~50% in hemp and sawdust substrates, respectively. The lignocellulose ingredients during fungal growth were degraded as follows: cellulose up to 7% and 28% in sawdust and hemp substrates, respectively, and lignin in the range of 13% in both substrates. A larger granulometric fraction in hemp MB ensured higher strength property but weakened water absorption (600-880%) performance. Perspective MB combinations regarding strength performance were hemp/BB and pure hemp MB (σ10 0.19-0.20 MPa; E 2.9 MPa), as well as sawdust/WB combination (σ10 0.23 MPa; E 2.9 MPa). WB positively affected fungal biomass yield, but elevated water absorption ability. WB improved compressive strength in the sawdust samples but decreased it in the hemp samples. BB supplement reduced water absorption by more than 100% and increased the density of sawdust and hemp samples. All MB samples were susceptible to mold contamination after full water immersion, with identified fungal genera Rhizopus, Trichoderma and Achremonium. The MB exhibited high biodegradability after 12 weeks' exposure in compost, and are therefore competitive with non-biodegradable synthetic foam materials.

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A green method for co-production of value-added xylooligosaccharides (XOS) and glucose from birch was demonstrated using hot water pretreatment. Effects of pretreatment severity factor (Log R0) on XOS production and enzymatic hydrolysis were investigated. At Log R0 of 4.05 (180 °C, 50 min), the maximum hydrolysis yield (80.8%) was obtained. At Log R0 of 3.91 (170 °C, 70 min), the maximum XOS yield (46.1%) was obtained, however the hydrolysis yield decreased to 70.3%. To achieve both the high XOS yield and high glucose output, Tween 80 addition (0.075 g/g cellulose) was employed, leading to an improvement in hydrolysis yield from 70.3% to 89.4%. From a mass balance perspective, 104.6 g of XOS and 372.9 g of glucose could be produced from 1000 g birch. These results demonstrated that birch sawdust is a promising lignocellulosic material for co-production of XOS and glucose.

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The objectives of this study were to investigate the medicinal mushroom Inonotus obliquus on the production of polysaccharides and changes of extracellular lignocellulolytic enzymes during submerged fermentation using alkali-treated birch sawdust as substrate. Meanwhile, in order to explore the degradation mode of lignocellulose in alkali-treated birch sawdust, degradation analysis of three components of lignocellulose was carried out. The fungus process in alkali-treated birch sawdust medium resulted in a higher degradation rate of cellulose, hemicellulose, and lignin of 39.24%, 51.00% and 31.3% after 11 days of submerged fermentation by the mycelium of I. obliquus, respectively. Maximal polysaccharide production and α-glucosidase inhibition rate determined in the alkali-treated birch sawdust medium were 6.93 mg/mL and 55.80%, while they were 4.98 mg/mL and 27.89% in the control. Moreover, high activities of laccase (51.95 IU/mL), CMCase (1.35 IU/mL), filter paper activity (0.50 IU/mL) and ß-glucosidase (0.55 IU/mL) were observed in alkali-treated birch sawdust medium, respectively. The results demonstrated that the addition of alkali-treated birch sawdust could promote the yield and α-glucosidase inhibition activity of polysaccharides and induce the production of cellulase and xylanase, indicating that alkali pretreatment was conducive to utilization of birch sawdust by I. obliquus.

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This study examined the effects of different pretreatments of birch sawdust on the production and activity of polysaccharides by Inonotus obliquus, and in order to explore the mechanism, structural characterization and analysis were carried out. The result clearly indicated that alkali treatment, ozone treatment, and alkali combined with ozone treatment of birch sawdust could be all helpful for the production of active polysaccharide by I. obliquus. Among four pretreatment groups, birch sawdust treated with alkali showed the highest increase in the exo-polysaccharide content (39.90%) and the inhibition rate of α-glucosidase (80.78%) within 11 days by the mycelium of I. obliquus through deep fermentation, in comparison to water-washed birch sawdust. Through a single-factor analysis and orthogonal experimental design, the optimum alkali treatment condition was as follows: NaOH concentration 1%, temperature 60 °C, and time 3 h. Moreover, the structural characteristics of pretreated birch sawdust with the optimum alkali treatment condition before and after fermentation by the mycelium of I. obliquus was performed by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electronic microscopy. The results showed that alkali treatment destroyed the lignin structure of birch sawdust, exposed the cellulose in the amorphous area, reduced the crystallinity of lignocellulose, and damaged the surface structure of birch sawdust, which had a further damage and a greater degradation degree of birch sawdust after fermentation, indicating that alkali pretreatment was beneficial for utilization of birch sawdust by I. obliquus.

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Catalytic hydrogenolysis of lignin to obtain value-added phenolic chemicals is a sustainable and cost-effective strategy for the efficient valorization of biomass derived wastes. Herein, an innovative approach by using a single-step microwave assisted depolymerization of lignin from birch sawdust without external hydrogen in the mixture of water-alcohol (methanol, ethanol, isopropanol) co-solvents over commercial catalysts (Pd/C, Pt/C, Ru/C) was investigated. A 65 wt% yield of phenolic monomers was obtained based on 43.8 wt% of delignification (190 °C, 3 h). The solid residues retained 92.0 wt% of cellulose and 57.3 wt% of hemicellulose, which could be further used for fermentation or in the pulp industry. Analysis of the lignin oil revealed that in-situ hydrogen generated from methanol decomposition promoted the hydrogenolysis of ßO4 ether linkage and selective hydrogenation of unsaturated side-chains of phenolic monomers. This work introduces new perspectives for the efficient and cost-effective production of value-added phenolic compounds from lignin in agro-industrial wastes without external hydrogen assisted by microwave heating.

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