Mycelium in architecture and industrial design: utilizing bio mechanisms to develop mycelium composites

So far, most of the intellectual property and academic study in the emerging field of mycelium-based composites was mainly focused on incubation of mycelium with plant-chips, sourced from regional agricultural and forest pruning residues that currently do not have practical discarding solutions. The initial part of our research explored the potential uses of mycelium-woodchip biocomposites for sustainable industrial design applications, using regional forest and agricultural wastes. One fundamental finding was that the mycelium is generally hydrophobic on its external areas; thus, it decreases the hydrophilic nature of the woodchips, commonly resulting in amphipathic water-interface properties. This finding established the scope for the second part of this study, that focused on exploring the potential of a bio-nanocomposite hybrid material made of mycelium and nanocellulose, presuming that an integration of these materials would produce resilient films with improved the water resistance.

The invention presents and includes composite materials that comprise mycelium in combination with plant-derived substances such as cellulose and/or cellulose-based materials. Our study explored the potential integration of the two forest-based materials, fungal mycelium and nanocellulose (NC) using submerged culture growing method. This is a commonly used method for industrial production of fungi, in which mycelium may be grown in enriched liquid broth with desired conditions, forming macroscopic hyphal aggregates, which are then processed to extract different microbial products.  In the current approach, the mycelium incubation is accompanied by the addition of NC to the liquid broth. These bio-based materials are exceptionally promising for sustainable industrial applications as they can be readily processed into applicable materials with versatile range of properties using similar infrastructure, tools, and methods of paper processing to produce materials such as films or sheets for packaging with valuable mechanical performance and barrier properties to oxygen, grease, UV, and humidity.

We found that white-rot mycelium grown in a liquid culture that includes growth nutrients and nanocellulose (CNC, CNF) incorporates the nanocellulose within its filamentous structure to give a mycelium-nanocellulose biocomposite hybrid. Generally, the strength of the mycelium is improved by the inclusion of nanocellulose and the surface properties of the resulting film are dominated by the mycelium, which is more hydrophobic and essentially coats and integrates within it the nanocellulose elements. This 1-step bio-fabrication of a mycelium-nanocellulose nanohybrid material gives materials that can be processed in the ways familiar to papermaking, are water-resistant, thermally stable, mechanically robust, and potentially anti-bacterial and anti-fungal. Of all the NC types tested (enzymatic CNF, carboxymethylated CNF, CNC), carboxymethylated CNF gives an increase in the yield of mycelial mass, all else kept equal. Lastly, simply adding nanocellulose to mycelium does not produce a uniform material, so the inclusion of nanocellulose in the growth medium is a key element.

Several analysis methods (XPS, POM, HR-SEM, FTIR, AFM, contact angle), supports the conclusion that in the invented material, NC (nm-scale and otherwise) is fully absorbed, interlaced, and engulfed by mycelium, and potentially integrated within the hyphal cells, respectively affecting physio mechanical material properties. This observation is perhaps most visually evidenced by POM, where the non-birefringent rippled hyphal network appears superimposed over the NC (see Attias et al. 2020). This observation was consistent across all NC types employed in this study, although their sizes, nano-yield, morphologies, and charges differed significantly. Furthermore, evidence was provided to support the assembly and integration of the NC nano-fraction within the hyphal cell walls and not simply aggregated onto the cell wall exterior as evident in studies that use mycelium to take in ions from the liquid media to form nanoparticles. In fact, we did not find any study that demonstrates an incorporation of nanoparticles into the fungal pellet/ cell wall.

Mycelium liquid culture is already quite straightforward and scalable fabrication process, however the main innovation is the addition of nanocellulose to the growth medium, by replacing the distilled water ingredient with NC in varied wt%, to produce an integrated NC-mycelium biocomposites with hybrid properties. Mycelium-nanocellulose bio-composites can be processed in the ways familiar to nanocellulose or mycelium-based composites, such as vacuum filtration, standard molding, 3D pulp molding, 3D printing, spraying, freeze dry etc. The results of our study suggest that a family of differentNC-mycelium bio-composites can be readily achieved by varying NC content and type, incubation time, nutrient profile, fungal species, growth conditions and material processing methods, with a potential to tailor diverse materials depending on the desired application of interest. Notably, we found that carboxymethylated CNF gives a higher yield of the mycelial mass and that the dewatering stage of a mycelium-NC hybrid is faster compared to pure NC processing.