This study investigates the mycelial biomass production and chitosan extraction potential of various Basidiomycota strains, including Heterobasidion annosum, Phanerochaete chrysosporium, Pleurotus ostreatus, Trametes versicolor, and Lentinus lepideus. Both submerged fermentation (SF) and solid-state fermentation (SSF) methods were employed. The chitosan yield in basidiocarps of Pleurotus ostreatus, Agaricus bisporus, and Ganoderma applanatum was also evaluated as a reference material. The chitosan extracted from fungal cells was characterized using elemental analyses and FTIR spectroscopy. Among the cultivated strains, P. chrysosporium exhibited the highest mycelial biomass concentration in SF (1.03 g 100 mL^–1) after 14 days, while T. versicolor achieved the highest biomass concentration in SSF (3.65 g 100 mL^–1). The highest chitosan yield was obtained from the mycelium of P. chrysosporium (0.38%) and T. versicolor (0.37%) in shaken SF. Additionally, commercially cultivated A. bisporus demonstrated the highest chitosan yield in fungal fruiting bodies (1.7%). The extracted chitosan holds potential as a functional biopolymer additive for eco-friendly materials, serving as an alternative to synthetic wet and dry strength agents in packaging materials.

To decrease climate changes, more research focuses on decreasing waste wood biomass (WWB) burning and increasing its conversion into value-added products. The WWB was isolated from model wood processing wastewater with a new hybrid coagulant by the coagulation/flocculation method. This study is aimed to characterize the WWB and to investigate its effect in the composition of a hybrid lignocellulosic filler on the properties of recycled polypropylene (rPP)-based wood–plastic composites (WPCs). The waste biomass contained high-molecular lignin and hemicelluloses substances and represented a finely dispersed powder. It was hydrophobic and was characterized by enhanced thermal stability. To minimize the negative effect of polymer wastes on the environment, recycled polypropylene as a polymer matrix was used with the hybrid filler in fabricating WPC samples. The presence of the coagulated WWB in the hybrid filler composition positively affects the mechanical properties, water uptake and dimensional stability of the composite samples. Such a behavior of the waste biomass showed its function as a compatibilizer, which promoted the interfacial adhesion in the composite system.

In the last two decades, there has been increased interest in research focused on developing innovative polymer composite materials for food packaging, obtained by compounding polymers with organic fillers, intended for the manufacture of food storage containers. Woodplastic composites (WPCs), due to high content of lignocellulosic filler, are consideredbiocomposites and can be used for the fabrication of such types of containers. Their formulations include, along with the matrix and the filler, functional additives. One of the most important considerations while developing a food packaging material is to choose eco-friendly additives. The suberinic acids (SAs), extracted from birch outer bark by hydrolysis in KOH water solution, were examined as lubricants in the formulation of recycled polypropylene/polylactic acid (rPP/PLA) composite filled with the alkali-treated milled birch shaving microparticles and proceeded by extrusion and injection molding. The incorporation of Sas in a birch wood-rPP/PLA composite was performed by treaing the wood microparticles with the SAs water suspension at the defined concentration. Their presence at the optimal content in the composite improved its processing by reducing the extruder rotor torque and injection pressure, which increased the mechanical properties and decreased the wettability of the composite.

The isolation and potential applications of chitosan from the fungal source is an alternative to crustacean chitosan and synthetic polymers. The strains of Basidiomycota (Heterobasidion annosum, Phanerochaete chrysosporium, Pleurotus ostreatus, Trametes versicolor, Lentinus lepideus) with different environmental distribution, ecological importance, and industrial application were studied for mycelial biomass production in submerged (SF) and solid state fermentation (SSF). Further, the chitosan from fungal cells was extracted and characterized by elemental analyses (nitrogen) and FTIR spectroscopy. The fruiting bodies of Pleurotus ostreatus, Agaricus bisporus and Ganoderma ap-planatum were chosen as a reference material of chitosan content in basidiocarps. Stationary SF gave the lowest biomass yield in comparison with shaken SF and SSF. The role of aeration and agitation in biomass production was clearly observed in shaken SF with the highest yield achieved by P. chrysosporium. The highest biomass yield in SSF produced P. ostreatus and T. versi-color. The content of chitosan within fungal species varied depending on the method of cultiva-tion. The highest chitosan yield among the cultivated strains was obtained from mycelium of P. chrysosporium and T. versicolor in SF. The highest chitosan yield in fungal fruiting bodies demon-strated commercially cultivated mushroom A. bisporus. The extracted chitosan is proposed as functional biopolymer additive for ecological materials to substitute the synthetic wet and dry strength agents in packaging materials.

Various pretreatment methods, often employed in wood biorefineries, aim to disrupt the wood architecture, thereby enhancing the efficiency of hemicellulose extraction for increasing the production of bio-ethanol, bio-gas, and bio-oil, as well as improving the pulping process. Pretreatment for the pulping process has advantages such as enhanced yield in biorefined products and reducing chemicals and energy consumption. This study examined the effect of an alkaline hydrolysis of birch sawdust on the chemical composition, aggregation ability, and surface activity of soda lignin obtained by soda pulping. The alkaline hydrolysis of birch sawdust led to a remarkable removal of hemicellulose and reduced its mechanical strength. The resorption of lignin fragments on the lignocellulosic matrix during the hydrolysis was observed. The soda pulping of the original and the treated sawdust was carried out under laboratory conditions at 165 °C for 90 min, using 4.5% sodium hydroxide. A higher yield of soda lignin and pulp was obtained from the treated sawdust. The reduced content of acidic and methoxyl groups in the chemical composition of the soda lignin from the hydrolyzed sawdust was explained by the predominance of polycondensation reactions in forming its primary structure. The changes in size and zeta potential values of the formed lignin particles, as well as in the modality of the size distribution with decreasing pH, were studied. The early-proposed suggestion about the existence of structural complementarity in the formation of the ordered lignin supermolecular structures has been testified. The higher surface activity at the air–water interface for the soda lignin extracted from the hydrolyzed sawdust, compared to the lignin from the original residue, was mainly attributed to a lower content of the acidic groups in its chemical composition, shifting the hydrophilic–hydrophobic balance of its structure toward hydrophobicity.

In pulping, the pretreatment of wood has advantages over untreated wood due to enhanced pulp yield and reduced chemical and energy consumption. This study examined the effect of alkaline treatment of birch sawdust on the chemical composition of the sawdust and soda lignin separated from black liquor obtained by soda pulping of the treated birch sawdust. It was found that the alkaline pre-treatment of birch sawdust led to a remarkable removal of hemicelluloses and reduced its mechanical strength. A lower content of acidic and methoxyl groups in the chemical composition of the alkaline lignin obtained by soda pulping of the pretreated sawdust showed the advantage of polycondensation reactions that proceeded during the formation of its primary structure over destruction. The possibility of using the modified soda lignin in a biocomposite was demonstrated. The composite material was fabricated from a blend of recycled polypropylene and polylactic acid, reinforced with ammoxidized wheat straw. The conducted mechanical tests demonstrated the potential of the modified soda lignin to replace more than 30% of the synthetic compatibilizer in the composite formulation without deteriorating the properties of the biocomposite.