Huaiyou Chen

Fungal mycelium‐based materials are highly valued for their versatility and for harnessing renewable plant biomass through sustainable biotechnological production. Heat pressing is often used to produce fungal particle boards and leather substitutes. In this study, the impact of heat pressing on fungal mycelium from the basidiomycete Fomes fomentarius under lignocellulose‐based solid‐state and glucose‐based liquid cultivation conditions is investigated, focusing on the changes in cell wall gene expression, morphology, chemical composition, hydrophobicity, and mechanical characteristics. With varying effects between two cultivations, heat pressing at 100 MPa changes hydrophobicity, increases tensile strength and stiffness, in line with hyphal compaction and bonding. Compared to mycelium grown on glucose‐based medium, lignocellulosic substrate leads to mycelium with higher β ‐glucan content, less densely packed mycelium structure and thus lower mechanical strength, probably due to the different expression of genes involved in glucan and chitin biosynthesis. This study highlights the impact of heat pressing on fungal mycelium obtained from different cultivation conditions, offering insights to tailor their performance.

This study applies extrusion-based additive manufacturing for the production of shape-defined, lightweight lignocellulose–fungal mycelium-based composites and pure 3D fungal mycelium skins, expanding the future applications of fungal materials.

To advance the concept of a circular economy, fungal mycelium-based materials are drawing increased attention as substitutes for nonsustainable materials, such as petroleum-based and animal-derived products, due to their biodegradability, low carbon footprint, and cruelty-free nature. Addressing the challenge of mechanical properties in fungal mycelium products, this study presents a straightforward approach for reinforcing fungal mycelium mats. This is achieved by using two bio-based and biodegradable polymers, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) and polylactic acid (PLA), via material extrusion additive manufacturing (MEX AM), commonly known as 3D printing, to produce fungal mycelium-biopolymer composites. By analyzing the mechanical properties, roughness, and morphology, this study demonstrates significant improvements in ultimate tensile strength with the application of PHBH and even more with PLA, while elasticity is reduced. The study also discusses potential improvements to enhance the quality of the fungal mycelium-biopolymer composites without trading off bio-based and biodegradable features, offering a promising pathway for the development of more durable and sustainable fungal mycelium products.

Background: Recent efforts in fungal biotechnology aim to develop new concepts and technologies that convert renewable plant biomass into innovative biomaterials. Hereby, plant substrates become metabolized by filamentous fungi to transform them into new fungal-based materials. Current research is thus focused on both understanding and optimizing the biology and genetics underlying filamentous fungal growth and on the development of new technologies to produce customized fungal-based materials. Results: This manuscript reports the production of stable pastes, composed of Fomes fomentarius mycelium, alginate and water with 71 wt.% mycelium in the solid content, for additive manufacturing of fungal-based composite materials. After printing complex shapes, such as hollow stars with up to 39 mm in height, a combination of freeze-drying and calcium-crosslinking processes allowed the printed shapes to remain stable even in the presence of water. The printed objects show low bulk densities of 0.12 ± 0.01 g/cm³ with interconnected macropores. Conclusions: This work reports for the first time the application of mycelium obtained from the tinder fungus F. fomentarius for an extrusion-based additive manufacturing approach to fabricate customized light-weight 3D objects. The process holds great promise for developing light-weight, stable, and porous fungal-based materials that could replace expanded polystyrene produced from fossil resources.